diff --git a/.github/agents/impl.agent.md b/.github/agents/impl.agent.md
index c577e13..072e291 100644
--- a/.github/agents/impl.agent.md
+++ b/.github/agents/impl.agent.md
@@ -10,7 +10,7 @@ tools:
     "todo",
     "ms-vscode.vscode-websearchforcopilot/websearch",
   ]
-model: "GPT-5.3-Codex"
+model: "GPT-5.4"
 ---
 
 与えられた実行計画に従って、実装を行ってください。TDD に倣って、以下のステップで実施します。
@@ -20,11 +20,12 @@ model: "GPT-5.3-Codex"
 1. 関連するドキュメントやコード、Issueの内容を確認する
 2. 網羅的なテストコードを使い作成する
 3. 開発ポリシーに従って #tool:edit などを使い実装する。変更はツールを利用し、 #tool:execute を使ったsedなどは使用しない。
-4. テストを #tool:execute などを使い実行し、成功を確認する
-5. 成功したらリファクタリングを行う
-6. リファクタリング後もテストが成功することを確認する
-7. 必要に応じてドキュメントを更新する
-8. 実装内容を説明する
+4. ある程度の編集粒度で、Gitにコミットする
+5. テストを #tool:execute などを使い実行し、成功を確認する
+6. 成功したらリファクタリングを行う
+7. リファクタリング後もテストが成功することを確認する
+8. 内容について、特筆すべき情報がある場合ドキュメントを作成・更新する
+9. 実装内容を説明する
 
 ## 注意事項
 
diff --git a/.github/agents/issue.agent.md b/.github/agents/issue.agent.md
index 65df49b..d50e5e8 100644
--- a/.github/agents/issue.agent.md
+++ b/.github/agents/issue.agent.md
@@ -10,7 +10,7 @@ tools:
     "web",
     "ms-vscode.vscode-websearchforcopilot/websearch",
   ]
-model: "GPT-5.3-Codex"
+model: "GPT-5.4"
 ---
 
 あなたは、ユーザーが入力する要望 (issue, bug report, feature request など) をもとに、イシューを管理するエージェントです。以下のステップに基づき、要件と仕様の解像度を高めながら、イシューを管理してください。
@@ -22,18 +22,17 @@ model: "GPT-5.3-Codex"
 3. 現在のローカル レポジトリ状況を確認する
 4. 現在の GitHub Issues の状況を確認する
 5. #tool:ms-vscode.vscode-websearchforcopilot/websearch でウェブ検索を行い、要件および要件に必要な周辺知識の理解を深める
-6. 要件と調査結果に基づき、十分な情報を含めたIssue を作成/更新する
+6. 要件と調査結果に基づき、十分な情報を含めたIssue を1つ以上作成/更新する
 7. 作成された Issue に対して批判的にレビューを行う
 8. レビュー内容に基づき、Issue を改善する
-9. `gh`を使用して Issue を作成し、ユーザーに作成した Issue とその内容を報告する
+9. `gh`を使用して Issue を作成し、ユーザーに作成したIssueリストとその内容を報告する
+
+## 注意事項
+
+- Issue の作成においては、巨大な要件で1つのIssueを作成するのではなく、必要に応じて複数の Issue に分割することを検討してください
+- 既存の Issue と重複する内容がないか確認してください。重複する内容がある場合は、既存の Issue を更新する形で対応してください
 
 ## ツール
 
 - #tool:ms-vscode.vscode-websearchforcopilot/websearch: ウェブ検索
 - `gh`: GitHub リポジトリの操作
-
-## ドキュメント
-
-- `docs/`
-- `README.md`
-- `CONTRIBUTING.md`
diff --git a/.github/agents/orchestrator.agent.md b/.github/agents/orchestrator.agent.md
index 977addc..efb6275 100644
--- a/.github/agents/orchestrator.agent.md
+++ b/.github/agents/orchestrator.agent.md
@@ -19,15 +19,14 @@ model: "GPT-5.3-Codex"
 
 ## 手順 (#tool:todo)
 
-要件に応じて、以下のステップを要件を満たすまで繰り返してください。
-
-1. #tool:agent/runSubagent で issue エージェントを呼び出し、イシューを作成する
-2. #tool:agent/runSubagent で plan エージェントを呼び出し、実装計画を立てる
-3. #tool:agent/runSubagent で impl エージェントを呼び出し、実装を行う
-4. #tool:agent/runSubagent で review エージェントを呼び出し、コードレビューと修正を行う
-5. 残っている要件に応じてステップ 3 と 4 を繰り返す
-6. #tool:agent/runSubagent で pr エージェントを呼び出し、プルリクエストを作成する
-7. 実装内容とプルリクエストのリンクをユーザーに通知する
+1. #tool:agent/runSubagent で issue エージェントを呼び出し、イシューを1つ以上作成する
+2. 作成したイシュー1つずつについて、以下を行い、実装を進める。エージェントにはissueのIDを渡して、イシューの内容を伝える。
+   - #tool:agent/runSubagent で plan エージェントを呼び出し、実装計画を立てる
+   - #tool:agent/runSubagent で impl エージェントを呼び出し、実装を行う
+   - #tool:agent/runSubagent で review エージェントを呼び出し、コードレビューと修正を行う
+   - レビューにてプルリクエストが作成OKとなるまで、上記の実装とレビューのサイクルを回す
+   - #tool:agent/runSubagent で pr エージェントを呼び出し、プルリクエストを作成する
+3. 実装内容とプルリクエストのリンクをユーザーに通知する
 
 ## 注意事項
 
diff --git a/.github/agents/plan.agent.md b/.github/agents/plan.agent.md
index acde1a7..2b3d324 100644
--- a/.github/agents/plan.agent.md
+++ b/.github/agents/plan.agent.md
@@ -9,7 +9,7 @@ tools:
     "web",
     "ms-vscode.vscode-websearchforcopilot/websearch",
   ]
-model: "GPT-5.3-Codex"
+model: "GPT-5.4"
 ---
 
 与えられたイシューの実装計画を立ててください。
@@ -18,9 +18,10 @@ model: "GPT-5.3-Codex"
 
 1. 現在のレポジトリ状況を確認し、リモートとの同期を行う
 2. 指定されたイシューの内容を確認する。イシューが存在しない場合は、処理を中止しユーザーに通知する。
-3. レポジトリ (コード、ドキュメント) を確認する
+3. レポジトリ (仕様、コード、ドキュメント) を確認する
 4. ウェブ検索で情報を収集する
-5. 実装計画をユーザーに提示する
+5. 技術的制約により仕様を変更する場合、仕様ファイル(`spec-*.md`)に反映する
+6. 実装計画をユーザーに提示する
 
 ## ツール
 
@@ -29,9 +30,7 @@ model: "GPT-5.3-Codex"
 
 ## ドキュメント
 
-- `docs/`
-- `README.md`
-- `CONTRIBUTING.md`
+- `spec-*.md`
 
 ## ブランチ戦略
 
diff --git a/.github/agents/pr.agent.md b/.github/agents/pr.agent.md
index 8f97820..8780db6 100644
--- a/.github/agents/pr.agent.md
+++ b/.github/agents/pr.agent.md
@@ -9,7 +9,7 @@ tools:
     "web",
     "ms-vscode.vscode-websearchforcopilot/websearch",
   ]
-model: "GPT-5.3-Codex"
+model: "Claude Sonnet 4.6"
 ---
 
 与えられたイシューと実装に対する、プルリクエストを作成してください。
diff --git a/.github/agents/review.agent.md b/.github/agents/review.agent.md
index 94786c2..a8b36da 100644
--- a/.github/agents/review.agent.md
+++ b/.github/agents/review.agent.md
@@ -1,5 +1,5 @@
 ---
-description: 実装内容をレビューし、建設的なフィードバックを提供します。
+description: Issueベースで実装内容をレビューし、建設的なフィードバックを提供します。
 tools:
   [
     "execute",
@@ -9,20 +9,22 @@ tools:
     "web",
     "ms-vscode.vscode-websearchforcopilot/websearch",
   ]
-model: "GPT-5.3-Codex"
+model: "GPT-5.4"
 ---
 
 実装内容をレビューしてください。批判的に評価を行い、発言についての中立的なレビューを提供してください。新たな情報を検索、分析することを推奨します。あくまでレビューの提供までがあなたの役割です。
 
 ## 手順 (#tool:todo)
 
+1. 与えられた課題が何であるかをIssueから理解する
 1. 網羅的に情報を収集する
    - レポジトリの分析
    - ドキュメント群の分析
    - ウェブ検索 (#tool:ms-vscode.vscode-websearchforcopilot/websearch) によるベストプラクティス、pitfalls、代替案の調査
    - 要件の確認と理解
-2. 収集した情報をもとに、実装内容を批判的に評価する (正確性、完全性、一貫性、正当性、妥当性、関連性、明確性、客観性、バイアスの有無、可読性、保守性、テストが十分であるかなどの観点)
-3. 改善点や懸念点があれば指摘し、アクションプランを示す
+   - spec-*.mdに含まれる仕様の確認
+1. 収集した情報をもとに、実装内容を批判的に評価する (正確性、完全性、一貫性、正当性、妥当性、関連性、明確性、客観性、バイアスの有無、可読性、保守性、テストが十分であるかなどの観点)
+1. 改善点や懸念点があれば指摘し、アクションプランを示す
 
 ## ツール
 
diff --git a/apps/backend/package.json b/apps/backend/package.json
index 243959a..1c6f916 100644
--- a/apps/backend/package.json
+++ b/apps/backend/package.json
@@ -25,11 +25,13 @@
     "better-auth": "^1.5.6",
     "drizzle-orm": "^0.45.2",
     "hono": "^4.12.9",
+    "nodemailer": "^8.0.5",
     "pg": "^8.13.3",
     "zod": "^4.3.6"
   },
   "devDependencies": {
     "@types/node": "^25.5.0",
+    "@types/nodemailer": "^8.0.0",
     "@types/pg": "^8.20.0",
     "drizzle-kit": "^0.31.10",
     "tsx": "^4.19.3"
diff --git a/apps/backend/src/__tests__/app.issue11.integration.test.ts b/apps/backend/src/__tests__/app.issue11.integration.test.ts
index c436292..edb4970 100644
--- a/apps/backend/src/__tests__/app.issue11.integration.test.ts
+++ b/apps/backend/src/__tests__/app.issue11.integration.test.ts
@@ -1211,10 +1211,13 @@ describe('issue #11 api integration', () => {
     expect(approveRes.status).toBe(200);
     expect(mockSendEmail).toHaveBeenCalledWith({
       to: 'owner@approve.example',
-      subject: 'Approve University の代表者招待',
-      html: expect.stringMatching(
-        /^招待リンク: invitation:[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/,
-      ),
+      template: 'university-owner-invitation-link',
+      payload: {
+        universityName: 'Approve University',
+        invitationLink: expect.stringMatching(
+          /^http:\/\/localhost:3000\/invite\/[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/,
+        ),
+      },
     });
     const approveJson = (await approveRes.json()) as {
       data: { status: string; createdOrganizationId: string };
diff --git a/apps/backend/src/auth.ts b/apps/backend/src/auth.ts
index 6000640..63561fa 100644
--- a/apps/backend/src/auth.ts
+++ b/apps/backend/src/auth.ts
@@ -4,6 +4,7 @@ import { organization } from 'better-auth/plugins';
 import { db } from './db/index.js';
 import * as schema from './db/schema.js';
 import { env } from './lib/config.js';
+import { buildInvitationLink } from './lib/invitation-link.js';
 import { verifyPassword } from './lib/password.js';
 import { emailService } from './services/email/index.js';
 
@@ -27,18 +28,50 @@ export const auth = betterAuth({
   trustedOrigins: env.CORS_ALLOWED_ORIGINS,
   emailAndPassword: {
     enabled: true,
+    requireEmailVerification: true,
+    autoSignIn: false,
+    async sendResetPassword({ user, url }) {
+      await emailService.sendEmail({
+        to: user.email,
+        template: 'password-reset',
+        payload: {
+          userName: user.name,
+          resetLink: url,
+        },
+      });
+    },
+    revokeSessionsOnPasswordReset: true,
     password: {
       verify: verifyPassword,
     },
   },
+  emailVerification: {
+    sendOnSignUp: true,
+    sendOnSignIn: true,
+    autoSignInAfterVerification: true,
+    async sendVerificationEmail({ user, url }) {
+      await emailService.sendEmail({
+        to: user.email,
+        template: 'email-verification',
+        payload: {
+          userName: user.name,
+          verificationLink: url,
+        },
+      });
+    },
+  },
   plugins: [
     organization({
       async sendInvitationEmail(data) {
-        const inviteLink = `${env.APP_URL}/invite/${data.id}`;
+        const inviteLink = buildInvitationLink(data.id);
         await emailService.sendEmail({
           to: data.email,
-          subject: `${data.organization.name} への招待`,
-          html: `${data.inviter.user.name} さんが ${data.organization.name} へ招待しました: ${inviteLink}`,
+          template: 'organization-invitation',
+          payload: {
+            organizationName: data.organization.name,
+            inviterName: data.inviter.user.name,
+            inviteLink,
+          },
         });
       },
     }),
diff --git a/apps/backend/src/lib/config.ts b/apps/backend/src/lib/config.ts
index d762e0f..8a1df6a 100644
--- a/apps/backend/src/lib/config.ts
+++ b/apps/backend/src/lib/config.ts
@@ -1,4 +1,4 @@
-type Env = {
+export type Env = {
   DATABASE_URL: string;
   PORT: number;
   BETTER_AUTH_SECRET: string;
@@ -12,9 +12,16 @@ type Env = {
   S3_BUCKET_RULES: string;
   S3_BUCKET_SUBMISSIONS: string;
   S3_FORCE_PATH_STYLE: boolean;
-  EMAIL_PROVIDER: 'console' | 'sendgrid';
+  EMAIL_PROVIDER: 'console' | 'sendgrid' | 'smtp';
   SENDGRID_API_KEY?: string;
   SENDGRID_FROM: string;
+  SMTP_HOST?: string;
+  SMTP_PORT: number;
+  SMTP_USER?: string;
+  SMTP_PASS?: string;
+  SMTP_FROM?: string;
+  SMTP_SECURE: boolean;
+  SMTP_REQUIRE_TLS: boolean;
 };
 
 const toBool = (value: string | undefined, fallback: boolean): boolean => {
@@ -51,7 +58,17 @@ export const env: Env = {
   S3_BUCKET_RULES: process.env.S3_BUCKET_RULES ?? 'robocon-rules',
   S3_BUCKET_SUBMISSIONS: process.env.S3_BUCKET_SUBMISSIONS ?? 'robocon-submissions',
   S3_FORCE_PATH_STYLE: toBool(process.env.S3_FORCE_PATH_STYLE, true),
-  EMAIL_PROVIDER: process.env.EMAIL_PROVIDER === 'sendgrid' ? 'sendgrid' : 'console',
+  EMAIL_PROVIDER:
+    process.env.EMAIL_PROVIDER === 'sendgrid' || process.env.EMAIL_PROVIDER === 'smtp'
+      ? process.env.EMAIL_PROVIDER
+      : 'console',
   SENDGRID_API_KEY: process.env.SENDGRID_API_KEY,
   SENDGRID_FROM: process.env.SENDGRID_FROM ?? 'noreply@example.com',
+  SMTP_HOST: process.env.SMTP_HOST,
+  SMTP_PORT: Number(process.env.SMTP_PORT ?? 587),
+  SMTP_USER: process.env.SMTP_USER,
+  SMTP_PASS: process.env.SMTP_PASS,
+  SMTP_FROM: process.env.SMTP_FROM,
+  SMTP_SECURE: toBool(process.env.SMTP_SECURE, false),
+  SMTP_REQUIRE_TLS: toBool(process.env.SMTP_REQUIRE_TLS, false),
 };
diff --git a/apps/backend/src/lib/invitation-link.ts b/apps/backend/src/lib/invitation-link.ts
new file mode 100644
index 0000000..351df08
--- /dev/null
+++ b/apps/backend/src/lib/invitation-link.ts
@@ -0,0 +1,4 @@
+import { env } from './config.js';
+
+export const buildInvitationLink = (invitationId: string): string =>
+  new URL(`/invite/${encodeURIComponent(invitationId)}`, env.APP_URL).toString();
diff --git a/apps/backend/src/middleware/organization.test.ts b/apps/backend/src/middleware/organization.test.ts
index 2b5e67d..cb96461 100644
--- a/apps/backend/src/middleware/organization.test.ts
+++ b/apps/backend/src/middleware/organization.test.ts
@@ -2,7 +2,7 @@ import type { Next } from 'hono';
 import { HTTPException } from 'hono/http-exception';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
-const mockLimit = vi.fn<() => Promise<Array<{ id: string }>>>(async () => []);
+const mockLimit = vi.fn<() => Promise<Array<{ organizationId: string }>>>(async () => []);
 
 vi.mock('../db/index.js', () => ({
   db: {
@@ -33,7 +33,7 @@ const createContext = (params: {
 }): TestContext => {
   const vars = new Map<string, unknown>();
   vars.set('currentUser', params.user);
-  vars.set('sessionActiveOrganizationId', params.sessionActiveOrganizationId ?? null);
+  vars.set('session', { activeOrganizationId: params.sessionActiveOrganizationId ?? null });
 
   return {
     req: {
@@ -63,7 +63,7 @@ describe('resolveOrganization', () => {
       headerOrganizationId: 'org-1',
       sessionActiveOrganizationId: 'org-1',
     });
-    mockLimit.mockResolvedValue([{ id: 'm-1' }]);
+    mockLimit.mockResolvedValue([{ organizationId: 'org-1' }]);
 
     await resolveOrganization(c as never, vi.fn(async () => undefined) as Next);
 
@@ -76,7 +76,7 @@ describe('resolveOrganization', () => {
       headerOrganizationId: 'org-header',
       sessionActiveOrganizationId: null,
     });
-    mockLimit.mockResolvedValue([{ id: 'm-1' }]);
+    mockLimit.mockResolvedValue([{ organizationId: 'org-header' }]);
 
     await resolveOrganization(c as never, vi.fn(async () => undefined) as Next);
 
@@ -99,7 +99,7 @@ describe('resolveOrganization', () => {
     const c = createContext({
       user: { id: 'user-1', isAdmin: false },
       headerOrganizationId: 'org-x',
-      sessionActiveOrganizationId: 'org-1',
+      sessionActiveOrganizationId: null,
     });
 
     await expect(
diff --git a/apps/backend/src/middleware/organization.ts b/apps/backend/src/middleware/organization.ts
index 36e57f0..9c1bb74 100644
--- a/apps/backend/src/middleware/organization.ts
+++ b/apps/backend/src/middleware/organization.ts
@@ -36,15 +36,23 @@ export const resolveOrganization: MiddlewareHandler<{
     )
     .limit(1);
 
-  if (!organizationId && rows.length > 0) {
+  if (organizationId && rows.length === 0) {
+    throw new HTTPException(403, {
+      message: 'Invalid organization context',
+    });
+  }
+
+  const fallbackOrganizationId = rows[0]?.organizationId ?? null;
+
+  if (!organizationId && fallbackOrganizationId && auth.api.setActiveOrganization) {
     await auth.api.setActiveOrganization({
       body: {
-        organizationId: rows[0].organizationId,
+        organizationId: fallbackOrganizationId,
       },
       headers: c.req.raw.headers,
     });
   }
 
-  c.set('organizationId', organizationId ?? rows[0]?.organizationId ?? null);
+  c.set('organizationId', organizationId ?? fallbackOrganizationId);
   await next();
 };
diff --git a/apps/backend/src/routes/admin/requests.ts b/apps/backend/src/routes/admin/requests.ts
index ecde31e..9ec57e4 100644
--- a/apps/backend/src/routes/admin/requests.ts
+++ b/apps/backend/src/routes/admin/requests.ts
@@ -11,6 +11,7 @@ import {
   universityCreationRequests,
   users,
 } from '../../db/schema.js';
+import { buildInvitationLink } from '../../lib/invitation-link.js';
 import {
   createPaginatedResponseSchema,
   createPaginationMeta,
@@ -613,8 +614,11 @@ adminRequestRoutes.openapi(approveUniversityRequestRoute, async (c) => {
 
   await emailService.sendEmail({
     to: request.representativeEmail,
-    subject: `${request.universityName} の代表者招待`,
-    html: `招待リンク: invitation:${invitationId}`,
+    template: 'university-owner-invitation-link',
+    payload: {
+      universityName: request.universityName,
+      invitationLink: buildInvitationLink(invitationId),
+    },
   });
 
   await db
diff --git a/apps/backend/src/routes/admin/universities.ts b/apps/backend/src/routes/admin/universities.ts
index e63004b..a12d5d0 100644
--- a/apps/backend/src/routes/admin/universities.ts
+++ b/apps/backend/src/routes/admin/universities.ts
@@ -3,6 +3,7 @@ import { createRoute, OpenAPIHono, z } from '@hono/zod-openapi';
 import { asc, count, desc, ilike, or } from 'drizzle-orm';
 import { db } from '../../db/index.js';
 import { invitations, organizations } from '../../db/schema.js';
+import { buildInvitationLink } from '../../lib/invitation-link.js';
 import {
   createPaginatedResponseSchema,
   createPaginationMeta,
@@ -134,8 +135,11 @@ adminUniversityRoutes.openapi(createUniversityRoute, async (c) => {
 
     await emailService.sendEmail({
       to: body.data.ownerEmail,
-      subject: `${inserted[0].name} の代表者招待`,
-      html: `招待ID: ${invitationId}`,
+      template: 'organization-member-invitation-link',
+      payload: {
+        organizationName: inserted[0].name,
+        invitationLink: buildInvitationLink(invitationId),
+      },
     });
   }
 
diff --git a/apps/backend/src/routes/university.ts b/apps/backend/src/routes/university.ts
index 99a1412..4d4a6ef 100644
--- a/apps/backend/src/routes/university.ts
+++ b/apps/backend/src/routes/university.ts
@@ -3,6 +3,7 @@ import { createRoute, OpenAPIHono, z } from '@hono/zod-openapi';
 import { and, asc, count, desc, eq, ilike, or } from 'drizzle-orm';
 import { db } from '../db/index.js';
 import { invitations, members, organizations, users } from '../db/schema.js';
+import { buildInvitationLink } from '../lib/invitation-link.js';
 import {
   createPaginatedResponseSchema,
   createPaginationMeta,
@@ -381,8 +382,11 @@ universityRoutes.openapi(inviteUniversityRoute, async (c) => {
 
   await emailService.sendEmail({
     to: body.data.email,
-    subject: `${inviter[0]?.orgName ?? organizationId} への招待`,
-    html: `招待リンク: invitation:${invitationId}`,
+    template: 'organization-member-invitation-link',
+    payload: {
+      organizationName: inviter[0]?.orgName ?? organizationId,
+      invitationLink: buildInvitationLink(invitationId),
+    },
   });
 
   return c.json({ data: inserted[0] }, 201);
diff --git a/apps/backend/src/services/email/console.test.ts b/apps/backend/src/services/email/console.test.ts
index c841ff3..3ca1a74 100644
--- a/apps/backend/src/services/email/console.test.ts
+++ b/apps/backend/src/services/email/console.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, vi } from 'vitest';
 import { ConsoleEmailService } from './console.js';
 
 describe('ConsoleEmailService', () => {
@@ -12,4 +12,35 @@ describe('ConsoleEmailService', () => {
 
     expect(result.success).toBe(true);
   });
+
+  it('resolves template-based emails before logging', async () => {
+    const service = new ConsoleEmailService();
+    const consoleLogSpy = vi.spyOn(console, 'log').mockImplementation(() => undefined);
+
+    const result = await service.sendEmail({
+      to: 'owner@example.com',
+      template: 'organization-invitation',
+      payload: {
+        organizationName: 'DocShare University',
+        inviterName: 'Admin User',
+        inviteLink: 'https://app.example.test/invite/inv-1',
+      },
+    });
+
+    expect(result.success).toBe(true);
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      '[EMAIL]',
+      expect.stringContaining('"subject":"DocShare University への招待"'),
+    );
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      '[EMAIL]',
+      expect.stringContaining('Admin User さんから'),
+    );
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      '[EMAIL]',
+      expect.stringContaining('"text":"DocShare University への招待'),
+    );
+
+    consoleLogSpy.mockRestore();
+  });
 });
diff --git a/apps/backend/src/services/email/console.ts b/apps/backend/src/services/email/console.ts
index 4f491f5..4114498 100644
--- a/apps/backend/src/services/email/console.ts
+++ b/apps/backend/src/services/email/console.ts
@@ -1,8 +1,10 @@
 import type { EmailService, SendEmailParams, SendEmailResult } from './interface.js';
+import { resolveSendEmailParams } from './templates.js';
 
 export class ConsoleEmailService implements EmailService {
   async sendEmail(params: SendEmailParams): Promise<SendEmailResult> {
-    console.log('[EMAIL]', JSON.stringify(params));
+    const resolved = resolveSendEmailParams(params);
+    console.log('[EMAIL]', JSON.stringify({ ...params, ...resolved }));
     return { success: true, messageId: 'console' };
   }
 }
diff --git a/apps/backend/src/services/email/index.test.ts b/apps/backend/src/services/email/index.test.ts
new file mode 100644
index 0000000..4d27751
--- /dev/null
+++ b/apps/backend/src/services/email/index.test.ts
@@ -0,0 +1,122 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import type { Env } from '../../lib/config.js';
+
+const createTransportMock = vi.fn(() => ({
+  sendMail: vi.fn(),
+}));
+const setApiKeyMock = vi.fn();
+
+vi.mock('nodemailer', () => ({
+  default: {
+    createTransport: createTransportMock,
+  },
+}));
+
+vi.mock('@sendgrid/mail', () => ({
+  default: {
+    send: vi.fn(),
+    setApiKey: setApiKeyMock,
+  },
+}));
+
+const createEnv = (overrides: Partial<Env> = {}): Env => ({
+  DATABASE_URL: 'postgres://robocon:password@localhost:5432/robocon',
+  PORT: 8787,
+  BETTER_AUTH_SECRET: 'dev-secret',
+  BETTER_AUTH_URL: 'http://localhost:8787',
+  APP_URL: 'http://localhost:3000',
+  CORS_ALLOWED_ORIGINS: ['http://localhost:3000'],
+  S3_ENDPOINT: 'http://localhost:9000',
+  S3_REGION: 'us-east-1',
+  S3_ACCESS_KEY: 'minioadmin',
+  S3_SECRET_KEY: 'minioadmin',
+  S3_BUCKET_RULES: 'robocon-rules',
+  S3_BUCKET_SUBMISSIONS: 'robocon-submissions',
+  S3_FORCE_PATH_STYLE: true,
+  EMAIL_PROVIDER: 'console',
+  SENDGRID_API_KEY: undefined,
+  SENDGRID_FROM: 'sendgrid@example.com',
+  SMTP_HOST: undefined,
+  SMTP_PORT: 587,
+  SMTP_USER: undefined,
+  SMTP_PASS: undefined,
+  SMTP_FROM: undefined,
+  SMTP_SECURE: false,
+  SMTP_REQUIRE_TLS: false,
+  ...overrides,
+});
+
+describe('createEmailService', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('uses console email by default', async () => {
+    const { createEmailService } = await import('./index.js');
+    const { ConsoleEmailService } = await import('./console.js');
+
+    expect(createEmailService(createEnv())).toBeInstanceOf(ConsoleEmailService);
+  });
+
+  it('uses SendGrid when configured with an API key', async () => {
+    const { createEmailService } = await import('./index.js');
+    const { SendGridEmailService } = await import('./sendgrid.js');
+
+    const service = createEmailService(
+      createEnv({
+        EMAIL_PROVIDER: 'sendgrid',
+        SENDGRID_API_KEY: 'sendgrid-key',
+      }),
+    );
+
+    expect(service).toBeInstanceOf(SendGridEmailService);
+    expect(setApiKeyMock).toHaveBeenCalledWith('sendgrid-key');
+  });
+
+  it('keeps the existing SendGrid fallback when the API key is missing', async () => {
+    const { createEmailService } = await import('./index.js');
+    const { ConsoleEmailService } = await import('./console.js');
+
+    expect(createEmailService(createEnv({ EMAIL_PROVIDER: 'sendgrid' }))).toBeInstanceOf(
+      ConsoleEmailService,
+    );
+  });
+
+  it('uses SMTP when all required SMTP settings are present', async () => {
+    const { createEmailService } = await import('./index.js');
+    const { SmtpEmailService } = await import('./smtp.js');
+
+    const service = createEmailService(
+      createEnv({
+        EMAIL_PROVIDER: 'smtp',
+        SMTP_HOST: 'smtp.example.com',
+        SMTP_PORT: 465,
+        SMTP_USER: 'smtp-user',
+        SMTP_PASS: 'smtp-pass',
+        SMTP_FROM: 'from@example.com',
+        SMTP_SECURE: true,
+        SMTP_REQUIRE_TLS: true,
+      }),
+    );
+
+    expect(service).toBeInstanceOf(SmtpEmailService);
+    expect(createTransportMock).toHaveBeenCalledWith({
+      host: 'smtp.example.com',
+      port: 465,
+      secure: true,
+      auth: {
+        user: 'smtp-user',
+        pass: 'smtp-pass',
+      },
+      requireTLS: true,
+    });
+  });
+
+  it('throws when SMTP provider is missing required settings', async () => {
+    const { createEmailService } = await import('./index.js');
+
+    expect(() => createEmailService(createEnv({ EMAIL_PROVIDER: 'smtp' }))).toThrow(
+      'EMAIL_PROVIDER=smtp requires SMTP_HOST, SMTP_USER, SMTP_PASS, SMTP_FROM.',
+    );
+  });
+});
diff --git a/apps/backend/src/services/email/index.ts b/apps/backend/src/services/email/index.ts
index badc0ce..897d980 100644
--- a/apps/backend/src/services/email/index.ts
+++ b/apps/backend/src/services/email/index.ts
@@ -1,9 +1,53 @@
-import { env } from '../../lib/config.js';
+import { type Env, env } from '../../lib/config.js';
 import { ConsoleEmailService } from './console.js';
 import type { EmailService } from './interface.js';
 import { SendGridEmailService } from './sendgrid.js';
+import { SmtpEmailService } from './smtp.js';
 
-export const emailService: EmailService =
-  env.EMAIL_PROVIDER === 'sendgrid' && env.SENDGRID_API_KEY
-    ? new SendGridEmailService(env.SENDGRID_API_KEY, env.SENDGRID_FROM)
-    : new ConsoleEmailService();
+export const createEmailService = (config: Env): EmailService => {
+  if (config.EMAIL_PROVIDER === 'sendgrid' && config.SENDGRID_API_KEY) {
+    return new SendGridEmailService(config.SENDGRID_API_KEY, config.SENDGRID_FROM);
+  }
+
+  if (config.EMAIL_PROVIDER === 'smtp') {
+    const smtpConfig = {
+      host: config.SMTP_HOST,
+      port: config.SMTP_PORT,
+      user: config.SMTP_USER,
+      pass: config.SMTP_PASS,
+      from: config.SMTP_FROM,
+      secure: config.SMTP_SECURE,
+      requireTLS: config.SMTP_REQUIRE_TLS,
+    };
+    const missing = [
+      ['SMTP_HOST', smtpConfig.host],
+      ['SMTP_USER', smtpConfig.user],
+      ['SMTP_PASS', smtpConfig.pass],
+      ['SMTP_FROM', smtpConfig.from],
+    ]
+      .filter(([, value]) => !value)
+      .map(([name]) => name);
+
+    if (missing.length > 0) {
+      throw new Error(`EMAIL_PROVIDER=smtp requires ${missing.join(', ')}.`);
+    }
+
+    if (!smtpConfig.host || !smtpConfig.user || !smtpConfig.pass || !smtpConfig.from) {
+      throw new Error('EMAIL_PROVIDER=smtp requires valid SMTP settings.');
+    }
+
+    return new SmtpEmailService({
+      host: smtpConfig.host,
+      port: smtpConfig.port,
+      user: smtpConfig.user,
+      pass: smtpConfig.pass,
+      from: smtpConfig.from,
+      secure: smtpConfig.secure,
+      requireTLS: smtpConfig.requireTLS,
+    });
+  }
+
+  return new ConsoleEmailService();
+};
+
+export const emailService: EmailService = createEmailService(env);
diff --git a/apps/backend/src/services/email/interface.ts b/apps/backend/src/services/email/interface.ts
index 35cee28..63f9c61 100644
--- a/apps/backend/src/services/email/interface.ts
+++ b/apps/backend/src/services/email/interface.ts
@@ -1,10 +1,51 @@
-export type SendEmailParams = {
+export type EmailTemplateMap = {
+  'organization-invitation': {
+    organizationName: string;
+    inviterName: string;
+    inviteLink: string;
+  };
+  'organization-member-invitation-link': {
+    organizationName: string;
+    invitationLink: string;
+  };
+  'university-owner-invitation-link': {
+    universityName: string;
+    invitationLink: string;
+  };
+  'email-verification': {
+    userName: string;
+    verificationLink: string;
+  };
+  'password-reset': {
+    userName: string;
+    resetLink: string;
+  };
+};
+
+export type EmailTemplateId = keyof EmailTemplateMap;
+
+export type SendEmailContentParams = {
   to: string;
   subject: string;
   html: string;
   text?: string;
+  template?: never;
+  payload?: never;
 };
 
+export type SendEmailTemplateParams = {
+  [TemplateId in EmailTemplateId]: {
+    to: string;
+    template: TemplateId;
+    payload: EmailTemplateMap[TemplateId];
+    text?: string;
+    subject?: never;
+    html?: never;
+  };
+}[EmailTemplateId];
+
+export type SendEmailParams = SendEmailContentParams | SendEmailTemplateParams;
+
 export type SendEmailResult = {
   success: boolean;
   messageId?: string;
diff --git a/apps/backend/src/services/email/sendgrid.test.ts b/apps/backend/src/services/email/sendgrid.test.ts
new file mode 100644
index 0000000..7a5fdea
--- /dev/null
+++ b/apps/backend/src/services/email/sendgrid.test.ts
@@ -0,0 +1,72 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const sendMock = vi.fn();
+const setApiKeyMock = vi.fn();
+
+vi.mock('@sendgrid/mail', () => ({
+  default: {
+    send: sendMock,
+    setApiKey: setApiKeyMock,
+  },
+}));
+
+describe('SendGridEmailService', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    sendMock.mockResolvedValue([
+      {
+        statusCode: 202,
+        headers: {
+          'x-message-id': 'message-1',
+        },
+      },
+    ]);
+  });
+
+  it('sends raw subject/html emails as-is', async () => {
+    const { SendGridEmailService } = await import('./sendgrid.js');
+    const service = new SendGridEmailService('test-key', 'from@example.com');
+
+    const result = await service.sendEmail({
+      to: 'owner@example.com',
+      subject: 'Hello',
+      html: '<p>World</p>',
+      text: 'World',
+    });
+
+    expect(setApiKeyMock).toHaveBeenCalledWith('test-key');
+    expect(sendMock).toHaveBeenCalledWith({
+      to: 'owner@example.com',
+      from: 'from@example.com',
+      subject: 'Hello',
+      html: '<p>World</p>',
+      text: 'World',
+    });
+    expect(result).toEqual({
+      success: true,
+      messageId: 'message-1',
+    });
+  });
+
+  it('resolves template-based emails before sending', async () => {
+    const { SendGridEmailService } = await import('./sendgrid.js');
+    const service = new SendGridEmailService('test-key', 'from@example.com');
+
+    await service.sendEmail({
+      to: 'owner@example.com',
+      template: 'university-owner-invitation-link',
+      payload: {
+        universityName: 'Approve University',
+        invitationLink: 'https://app.example.test/invite/invite-1',
+      },
+    });
+
+    expect(sendMock).toHaveBeenCalledWith({
+      to: 'owner@example.com',
+      from: 'from@example.com',
+      subject: 'Approve University の代表者招待',
+      html: expect.stringContaining('https://app.example.test/invite/invite-1'),
+      text: expect.stringContaining('代表者設定を開く: https://app.example.test/invite/invite-1'),
+    });
+  });
+});
diff --git a/apps/backend/src/services/email/sendgrid.ts b/apps/backend/src/services/email/sendgrid.ts
index f7b6312..2e07af7 100644
--- a/apps/backend/src/services/email/sendgrid.ts
+++ b/apps/backend/src/services/email/sendgrid.ts
@@ -1,5 +1,6 @@
 import sendgridMail from '@sendgrid/mail';
 import type { EmailService, SendEmailParams, SendEmailResult } from './interface.js';
+import { resolveSendEmailParams } from './templates.js';
 
 export class SendGridEmailService implements EmailService {
   constructor(
@@ -10,12 +11,13 @@ export class SendGridEmailService implements EmailService {
   }
 
   async sendEmail(params: SendEmailParams): Promise<SendEmailResult> {
+    const resolved = resolveSendEmailParams(params);
     const [res] = await sendgridMail.send({
-      to: params.to,
+      to: resolved.to,
       from: this.fromAddress,
-      subject: params.subject,
-      html: params.html,
-      text: params.text,
+      subject: resolved.subject,
+      html: resolved.html,
+      text: resolved.text,
     });
 
     return {
diff --git a/apps/backend/src/services/email/smtp.test.ts b/apps/backend/src/services/email/smtp.test.ts
new file mode 100644
index 0000000..549d34d
--- /dev/null
+++ b/apps/backend/src/services/email/smtp.test.ts
@@ -0,0 +1,108 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const sendMailMock = vi.fn();
+const createTransportMock = vi.fn(() => ({
+  sendMail: sendMailMock,
+}));
+
+vi.mock('nodemailer', () => ({
+  default: {
+    createTransport: createTransportMock,
+  },
+}));
+
+describe('SmtpEmailService', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    sendMailMock.mockResolvedValue({
+      messageId: 'smtp-message-1',
+    });
+  });
+
+  it('creates a transporter with SMTP settings', async () => {
+    const { SmtpEmailService } = await import('./smtp.js');
+
+    new SmtpEmailService({
+      host: 'smtp.example.com',
+      port: 465,
+      user: 'smtp-user',
+      pass: 'smtp-pass',
+      from: 'from@example.com',
+      secure: true,
+      requireTLS: true,
+    });
+
+    expect(createTransportMock).toHaveBeenCalledWith({
+      host: 'smtp.example.com',
+      port: 465,
+      secure: true,
+      auth: {
+        user: 'smtp-user',
+        pass: 'smtp-pass',
+      },
+      requireTLS: true,
+    });
+  });
+
+  it('sends raw subject/html emails as-is', async () => {
+    const { SmtpEmailService } = await import('./smtp.js');
+    const service = new SmtpEmailService({
+      host: 'smtp.example.com',
+      port: 587,
+      user: 'smtp-user',
+      pass: 'smtp-pass',
+      from: 'from@example.com',
+      secure: false,
+      requireTLS: false,
+    });
+
+    const result = await service.sendEmail({
+      to: 'owner@example.com',
+      subject: 'Hello',
+      html: '<p>World</p>',
+      text: 'World',
+    });
+
+    expect(sendMailMock).toHaveBeenCalledWith({
+      to: 'owner@example.com',
+      from: 'from@example.com',
+      subject: 'Hello',
+      html: '<p>World</p>',
+      text: 'World',
+    });
+    expect(result).toEqual({
+      success: true,
+      messageId: 'smtp-message-1',
+    });
+  });
+
+  it('resolves template-based emails before sending', async () => {
+    const { SmtpEmailService } = await import('./smtp.js');
+    const service = new SmtpEmailService({
+      host: 'smtp.example.com',
+      port: 587,
+      user: 'smtp-user',
+      pass: 'smtp-pass',
+      from: 'from@example.com',
+      secure: false,
+      requireTLS: true,
+    });
+
+    await service.sendEmail({
+      to: 'owner@example.com',
+      template: 'university-owner-invitation-link',
+      payload: {
+        universityName: 'Approve University',
+        invitationLink: 'https://app.example.test/invite/invite-1',
+      },
+    });
+
+    expect(sendMailMock).toHaveBeenCalledWith({
+      to: 'owner@example.com',
+      from: 'from@example.com',
+      subject: 'Approve University の代表者招待',
+      html: expect.stringContaining('https://app.example.test/invite/invite-1'),
+      text: expect.stringContaining('代表者設定を開く: https://app.example.test/invite/invite-1'),
+    });
+  });
+});
diff --git a/apps/backend/src/services/email/smtp.ts b/apps/backend/src/services/email/smtp.ts
new file mode 100644
index 0000000..790dab2
--- /dev/null
+++ b/apps/backend/src/services/email/smtp.ts
@@ -0,0 +1,47 @@
+import nodemailer, { type Transporter } from 'nodemailer';
+import type SMTPTransport from 'nodemailer/lib/smtp-transport/index.js';
+import type { EmailService, SendEmailParams, SendEmailResult } from './interface.js';
+import { resolveSendEmailParams } from './templates.js';
+
+export type SmtpEmailServiceConfig = {
+  host: string;
+  port: number;
+  user: string;
+  pass: string;
+  from: string;
+  secure: boolean;
+  requireTLS: boolean;
+};
+
+export class SmtpEmailService implements EmailService {
+  private readonly transporter: Transporter<SMTPTransport.SentMessageInfo, SMTPTransport.Options>;
+
+  constructor(private readonly config: SmtpEmailServiceConfig) {
+    this.transporter = nodemailer.createTransport({
+      host: config.host,
+      port: config.port,
+      secure: config.secure,
+      auth: {
+        user: config.user,
+        pass: config.pass,
+      },
+      requireTLS: config.requireTLS,
+    });
+  }
+
+  async sendEmail(params: SendEmailParams): Promise<SendEmailResult> {
+    const resolved = resolveSendEmailParams(params);
+    const info = await this.transporter.sendMail({
+      to: resolved.to,
+      from: this.config.from,
+      subject: resolved.subject,
+      html: resolved.html,
+      text: resolved.text,
+    });
+
+    return {
+      success: true,
+      messageId: info.messageId,
+    };
+  }
+}
diff --git a/apps/backend/src/services/email/templates.test.ts b/apps/backend/src/services/email/templates.test.ts
new file mode 100644
index 0000000..52f2557
--- /dev/null
+++ b/apps/backend/src/services/email/templates.test.ts
@@ -0,0 +1,90 @@
+import { describe, expect, it } from 'vitest';
+import { resolveEmailTemplate } from './templates.js';
+
+describe('resolveEmailTemplate', () => {
+  it('renders organization invitation emails', () => {
+    const email = resolveEmailTemplate('organization-invitation', {
+      organizationName: 'DocShare University',
+      inviterName: 'Admin User',
+      inviteLink: 'https://app.example.test/invite/inv-1',
+    });
+
+    expect(email.subject).toBe('DocShare University への招待');
+    expect(email.html).toContain('Admin User さんから');
+    expect(email.html).toContain('DocShare の DocShare University');
+    expect(email.html).toContain('https://app.example.test/invite/inv-1');
+    expect(email.text).toContain('Admin User さんから');
+    expect(email.text).toContain('https://app.example.test/invite/inv-1');
+  });
+
+  it('renders invitation link-based owner emails', () => {
+    const email = resolveEmailTemplate('university-owner-invitation-link', {
+      universityName: 'Approve University',
+      invitationLink: 'https://app.example.test/invite/1234',
+    });
+
+    expect(email.subject).toBe('Approve University の代表者招待');
+    expect(email.html).toContain('代表者アカウントを設定するための招待リンク');
+    expect(email.html).toContain('https://app.example.test/invite/1234');
+    expect(email.text).toContain('代表者アカウントを設定するための招待リンク');
+    expect(email.text).toContain('代表者設定を開く: https://app.example.test/invite/1234');
+  });
+
+  it('renders member invitation emails', () => {
+    const email = resolveEmailTemplate('organization-member-invitation-link', {
+      organizationName: 'Engineering Org',
+      invitationLink: 'https://app.example.test/invite/5678',
+    });
+
+    expect(email.subject).toBe('Engineering Org への招待');
+    expect(email.html).toContain('メンバーとして参加するための招待リンク');
+    expect(email.html).toContain('https://app.example.test/invite/5678');
+    expect(email.text).toContain('メンバーとして参加するための招待リンク');
+    expect(email.text).toContain('メンバー招待を開く: https://app.example.test/invite/5678');
+  });
+
+  it('renders email verification emails', () => {
+    const email = resolveEmailTemplate('email-verification', {
+      userName: 'New User',
+      verificationLink: 'https://app.example.test/auth/verify-email?token=token-1',
+    });
+
+    expect(email.subject).toBe('DocShare メールアドレスの確認');
+    expect(email.html).toContain('New User さん');
+    expect(email.html).toContain('メールアドレスの確認を完了してください');
+    expect(email.text).toContain(
+      'メールアドレスを確認する: https://app.example.test/auth/verify-email?token=token-1',
+    );
+  });
+
+  it('renders password reset emails', () => {
+    const email = resolveEmailTemplate('password-reset', {
+      userName: 'Existing User',
+      resetLink: 'https://app.example.test/auth/reset-password?token=token-2',
+    });
+
+    expect(email.subject).toBe('DocShare パスワード再設定');
+    expect(email.html).toContain('Existing User さん');
+    expect(email.html).toContain('パスワード再設定がリクエストされました');
+    expect(email.text).toContain(
+      'パスワードを再設定する: https://app.example.test/auth/reset-password?token=token-2',
+    );
+  });
+
+  it('escapes dynamic values in html output', () => {
+    const email = resolveEmailTemplate('organization-invitation', {
+      organizationName: 'R&D <Team>',
+      inviterName: 'Admin & Owner',
+      inviteLink: 'https://app.example.test/invite?token=<abc>&next="home"',
+    });
+
+    expect(email.subject).toBe('R&D <Team> への招待');
+    expect(email.html).toContain('R&amp;D &lt;Team&gt;');
+    expect(email.html).toContain('Admin &amp; Owner');
+    expect(email.html).toContain(
+      'https://app.example.test/invite?token=&lt;abc&gt;&amp;next=&quot;home&quot;',
+    );
+    expect(email.text).toContain('R&D <Team>');
+    expect(email.text).toContain('Admin & Owner');
+  });
+});
diff --git a/apps/backend/src/services/email/templates.ts b/apps/backend/src/services/email/templates.ts
new file mode 100644
index 0000000..887100f
--- /dev/null
+++ b/apps/backend/src/services/email/templates.ts
@@ -0,0 +1,192 @@
+import type {
+  EmailTemplateId,
+  EmailTemplateMap,
+  SendEmailContentParams,
+  SendEmailParams,
+  SendEmailTemplateParams,
+} from './interface.js';
+
+type EmailTemplateDefinition<TemplateId extends EmailTemplateId> = {
+  render: (payload: EmailTemplateMap[TemplateId]) => Omit<SendEmailContentParams, 'to'>;
+};
+
+type EmailTemplateContent = {
+  subject: string;
+  heading: string;
+  body: string[];
+  action?: {
+    label: string;
+    href: string;
+  };
+  detail?: {
+    label: string;
+    value: string;
+  };
+};
+
+const escapeHtml = (value: string): string =>
+  value.replace(/[&<>"']/g, (char) => {
+    switch (char) {
+      case '&':
+        return '&amp;';
+      case '<':
+        return '&lt;';
+      case '>':
+        return '&gt;';
+      case '"':
+        return '&quot;';
+      case "'":
+        return '&#39;';
+      default:
+        return char;
+    }
+  });
+
+const renderParagraphs = (paragraphs: string[]): string =>
+  paragraphs
+    .map((paragraph) => `<p style="margin: 0 0 16px;">${escapeHtml(paragraph)}</p>`)
+    .join('');
+
+const renderEmail = (content: EmailTemplateContent): Omit<SendEmailContentParams, 'to'> => {
+  const detailText = content.detail
+    ? `${content.detail.label}: ${content.detail.value}`
+    : undefined;
+  const actionText = content.action ? `${content.action.label}: ${content.action.href}` : undefined;
+  const text = [
+    content.heading,
+    '',
+    ...content.body,
+    ...(detailText ? ['', detailText] : []),
+    ...(actionText ? ['', actionText] : []),
+    '',
+    'このメールに心当たりがない場合は、破棄してください。',
+    '',
+    'DocShare',
+  ].join('\n');
+
+  const detailHtml = content.detail
+    ? `<div style="margin: 20px 0; padding: 14px 16px; background: #f8fafc; border: 1px solid #e2e8f0; border-radius: 6px;">
+        <div style="font-size: 13px; color: #475569; margin-bottom: 6px;">${escapeHtml(content.detail.label)}</div>
+        <div style="font-size: 16px; color: #0f172a; font-weight: 600; word-break: break-all;">${escapeHtml(content.detail.value)}</div>
+      </div>`
+    : '';
+  const actionHtml = content.action
+    ? `<div style="margin: 24px 0;">
+        <a href="${escapeHtml(content.action.href)}" style="display: inline-block; padding: 12px 18px; background: #2563eb; color: #ffffff; text-decoration: none; border-radius: 6px; font-weight: 600;">${escapeHtml(content.action.label)}</a>
+      </div>
+      <p style="margin: 0 0 16px; color: #475569; font-size: 13px; word-break: break-all;">ボタンを開けない場合は、次のURLをブラウザに貼り付けてください。<br>${escapeHtml(content.action.href)}</p>`
+    : '';
+
+  return {
+    subject: content.subject,
+    html: `<div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; color: #0f172a; line-height: 1.7;">
+      <h1 style="font-size: 20px; line-height: 1.4; margin: 0 0 20px;">${escapeHtml(content.heading)}</h1>
+      ${renderParagraphs(content.body)}
+      ${detailHtml}
+      ${actionHtml}
+      <p style="margin: 24px 0 0; color: #475569; font-size: 13px;">このメールに心当たりがない場合は、破棄してください。</p>
+      <p style="margin: 24px 0 0;">DocShare</p>
+    </div>`,
+    text,
+  };
+};
+
+const emailTemplateDefinitions: {
+  [TemplateId in EmailTemplateId]: EmailTemplateDefinition<TemplateId>;
+} = {
+  'organization-invitation': {
+    render: (payload) =>
+      renderEmail({
+        subject: `${payload.organizationName} への招待`,
+        heading: `${payload.organizationName} への招待`,
+        body: [
+          `${payload.inviterName} さんから、DocShare の ${payload.organizationName} に参加するための招待が届いています。`,
+          '以下のリンクから参加手続きを完了してください。',
+        ],
+        action: {
+          label: '招待を確認する',
+          href: payload.inviteLink,
+        },
+      }),
+  },
+  'organization-member-invitation-link': {
+    render: (payload) =>
+      renderEmail({
+        subject: `${payload.organizationName} への招待`,
+        heading: `${payload.organizationName} への招待`,
+        body: [
+          `DocShare の ${payload.organizationName} にメンバーとして参加するための招待リンクをお送りします。`,
+          '以下のリンクからアカウントの確認または登録を進めてください。',
+        ],
+        action: {
+          label: 'メンバー招待を開く',
+          href: payload.invitationLink,
+        },
+      }),
+  },
+  'university-owner-invitation-link': {
+    render: (payload) =>
+      renderEmail({
+        subject: `${payload.universityName} の代表者招待`,
+        heading: `${payload.universityName} の代表者招待`,
+        body: [
+          `DocShare で ${payload.universityName} の代表者アカウントを設定するための招待リンクをお送りします。`,
+          '以下のリンクから代表者アカウントの設定を完了してください。',
+        ],
+        action: {
+          label: '代表者設定を開く',
+          href: payload.invitationLink,
+        },
+      }),
+  },
+  'email-verification': {
+    render: (payload) =>
+      renderEmail({
+        subject: 'DocShare メールアドレスの確認',
+        heading: 'メールアドレスの確認',
+        body: [
+          `${payload.userName} さん、DocShare への登録ありがとうございます。`,
+          '以下のリンクからメールアドレスの確認を完了してください。',
+        ],
+        action: {
+          label: 'メールアドレスを確認する',
+          href: payload.verificationLink,
+        },
+      }),
+  },
+  'password-reset': {
+    render: (payload) =>
+      renderEmail({
+        subject: 'DocShare パスワード再設定',
+        heading: 'パスワード再設定',
+        body: [
+          `${payload.userName} さんの DocShare アカウントで、パスワード再設定がリクエストされました。`,
+          '以下のリンクから新しいパスワードを設定してください。',
+        ],
+        action: {
+          label: 'パスワードを再設定する',
+          href: payload.resetLink,
+        },
+      }),
+  },
+};
+
+export const resolveEmailTemplate = <TemplateId extends EmailTemplateId>(
+  template: TemplateId,
+  payload: EmailTemplateMap[TemplateId],
+): Omit<SendEmailContentParams, 'to'> => emailTemplateDefinitions[template].render(payload);
+
+const isTemplateEmail = (params: SendEmailParams): params is SendEmailTemplateParams =>
+  'template' in params;
+
+export const resolveSendEmailParams = (params: SendEmailParams): SendEmailContentParams => {
+  if (!isTemplateEmail(params)) {
+    return params;
+  }
+
+  return {
+    to: params.to,
+    text: params.text,
+    ...resolveEmailTemplate(params.template, params.payload),
+  };
+};
diff --git a/apps/frontend/app/(admin)/admin/editions/page.tsx b/apps/frontend/app/(admin)/admin/editions/page.tsx
index ba110f9..2df0874 100644
--- a/apps/frontend/app/(admin)/admin/editions/page.tsx
+++ b/apps/frontend/app/(admin)/admin/editions/page.tsx
@@ -30,14 +30,17 @@ import {
   useDeleteEditionMutation,
   useUploadEditionRuleMutation,
 } from '@/features/admin/editions/mutations';
-import { useAdminEditionsList } from '@/features/admin/editions/query';
+import { useAdminEditionsList, useSeriesForEditionForm } from '@/features/admin/editions/query';
 import type { Edition, SharingStatus } from '@/features/admin/editions/types';
 import { SHARING_STATUS_LABELS } from '@/features/admin/editions/types';
 
+const ALL_SERIES_VALUE = 'all';
+
 const paginationParsers = {
   page: parseAsInteger.withDefault(1),
   pageSize: parseAsInteger.withDefault(20),
   q: parseAsString.withDefault(''),
+  seriesId: parseAsString.withDefault(''),
 };
 
 export default function AdminEditionsPage() {
@@ -48,9 +51,12 @@ export default function AdminEditionsPage() {
   const [uploadingEditionId, setUploadingEditionId] = useState<string | null>(null);
 
   const { data, isLoading } = useAdminEditionsList(queryParams);
+  const { data: seriesData } = useSeriesForEditionForm();
   const deleteMutation = useDeleteEditionMutation();
   const changeStatusMutation = useChangeEditionStatusMutation();
   const uploadRuleMutation = useUploadEditionRuleMutation();
+  const series = seriesData?.data ?? [];
+  const selectedSeries = series.find((item) => item.id === queryParams.seriesId);
 
   const handleRuleUpload = async (editionId: string, file: File) => {
     const edition = data?.data.find((item) => item.id === editionId);
@@ -169,7 +175,28 @@ export default function AdminEditionsPage() {
       />
       <div className='flex items-center justify-between gap-3 flex-wrap'>
         <h1 className='text-2xl font-bold'>大会回管理</h1>
-        <div className='flex gap-2'>
+        <div className='flex gap-2 flex-wrap'>
+          <Select
+            value={queryParams.seriesId || ALL_SERIES_VALUE}
+            onValueChange={(value) =>
+              setQueryParams({
+                seriesId: value === ALL_SERIES_VALUE ? '' : value,
+                page: 1,
+              })
+            }
+          >
+            <SelectTrigger className='w-48'>
+              <SelectValue>{selectedSeries ? selectedSeries.name : 'すべてのシリーズ'}</SelectValue>
+            </SelectTrigger>
+            <SelectContent>
+              <SelectItem value={ALL_SERIES_VALUE}>すべてのシリーズ</SelectItem>
+              {series.map((item) => (
+                <SelectItem key={item.id} value={item.id}>
+                  {item.name}
+                </SelectItem>
+              ))}
+            </SelectContent>
+          </Select>
           <Input
             placeholder='検索...'
             defaultValue={queryParams.q}
diff --git a/apps/frontend/app/(public)/auth/forgot-password/page.tsx b/apps/frontend/app/(public)/auth/forgot-password/page.tsx
new file mode 100644
index 0000000..2018a15
--- /dev/null
+++ b/apps/frontend/app/(public)/auth/forgot-password/page.tsx
@@ -0,0 +1,83 @@
+'use client';
+
+import Link from 'next/link';
+import { useState } from 'react';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { Input } from '@/components/ui/input';
+import { useForgotPasswordForm } from '@/features/public/auth/forgot-password/hooks';
+
+export default function ForgotPasswordPage() {
+  const [sentEmail, setSentEmail] = useState<string | null>(null);
+  const { form, error, validators } = useForgotPasswordForm((email) => {
+    setSentEmail(email);
+  });
+
+  if (sentEmail) {
+    return (
+      <div className='container mx-auto px-4 py-16 flex justify-center'>
+        <Card className='w-full max-w-md'>
+          <CardHeader>
+            <CardTitle>再設定メールを送信しました</CardTitle>
+            <CardDescription>{sentEmail} に再設定リンクを送信しました</CardDescription>
+          </CardHeader>
+          <CardContent>
+            <p className='text-sm text-muted-foreground'>
+              メール内のリンクから新しいパスワードを設定してください。
+            </p>
+          </CardContent>
+        </Card>
+      </div>
+    );
+  }
+
+  return (
+    <div className='container mx-auto px-4 py-16 flex justify-center'>
+      <Card className='w-full max-w-md'>
+        <CardHeader>
+          <CardTitle>パスワード再設定</CardTitle>
+          <CardDescription>登録済みのメールアドレスへ再設定リンクを送信します</CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form
+            onSubmit={(e) => {
+              e.preventDefault();
+              form.handleSubmit();
+            }}
+            className='space-y-4'
+          >
+            <form.Field name='email' validators={{ onChange: validators.email }}>
+              {(field) => (
+                <div className='space-y-1'>
+                  <label htmlFor={field.name} className='text-sm font-medium'>
+                    メールアドレス
+                  </label>
+                  <Input
+                    id={field.name}
+                    type='email'
+                    placeholder='you@example.com'
+                    value={field.state.value}
+                    onBlur={field.handleBlur}
+                    onChange={(e) => field.handleChange(e.target.value)}
+                  />
+                  {field.state.meta.errors[0] && (
+                    <p className='text-sm text-destructive'>{field.state.meta.errors[0].message}</p>
+                  )}
+                </div>
+              )}
+            </form.Field>
+            {error && <p className='text-sm text-destructive'>{error}</p>}
+            <Button type='submit' className='w-full' disabled={form.state.isSubmitting}>
+              {form.state.isSubmitting ? '送信中...' : '再設定メールを送信'}
+            </Button>
+          </form>
+          <p className='text-sm text-center text-muted-foreground mt-4'>
+            <Link href='/auth/login' className='text-primary hover:underline'>
+              ログインへ戻る
+            </Link>
+          </p>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
diff --git a/apps/frontend/app/(public)/auth/login/page.tsx b/apps/frontend/app/(public)/auth/login/page.tsx
index c9c2b71..3cf8977 100644
--- a/apps/frontend/app/(public)/auth/login/page.tsx
+++ b/apps/frontend/app/(public)/auth/login/page.tsx
@@ -83,6 +83,11 @@ function LoginPageContent() {
               {form.state.isSubmitting ? 'ログイン中...' : 'ログイン'}
             </Button>
           </form>
+          <p className='text-sm text-center text-muted-foreground mt-4'>
+            <Link href='/auth/forgot-password' className='text-primary hover:underline'>
+              パスワードをお忘れの方
+            </Link>
+          </p>
           <p className='text-sm text-center text-muted-foreground mt-4'>
             アカウントをお持ちでない方は{' '}
             <Link href='/auth/register' className='text-primary hover:underline'>
diff --git a/apps/frontend/app/(public)/auth/register/page.tsx b/apps/frontend/app/(public)/auth/register/page.tsx
index 40b28b3..1691374 100644
--- a/apps/frontend/app/(public)/auth/register/page.tsx
+++ b/apps/frontend/app/(public)/auth/register/page.tsx
@@ -2,6 +2,7 @@
 
 import Link from 'next/link';
 import { useRouter } from 'next/navigation';
+import { useState } from 'react';
 import { Button } from '@/components/ui/button';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
 import { Input } from '@/components/ui/input';
@@ -9,10 +10,32 @@ import { useRegisterForm } from '@/features/public/auth/register/hooks';
 
 export default function RegisterPage() {
   const router = useRouter();
-  const { form, error, validators } = useRegisterForm(() => {
-    router.push('/dashboard');
+  const [registeredEmail, setRegisteredEmail] = useState<string | null>(null);
+  const { form, error, validators } = useRegisterForm((email) => {
+    setRegisteredEmail(email);
   });
 
+  if (registeredEmail) {
+    return (
+      <div className='container mx-auto px-4 py-16 flex justify-center'>
+        <Card className='w-full max-w-md'>
+          <CardHeader>
+            <CardTitle>確認メールを送信しました</CardTitle>
+            <CardDescription>{registeredEmail} に確認リンクを送信しました</CardDescription>
+          </CardHeader>
+          <CardContent className='space-y-4'>
+            <p className='text-sm text-muted-foreground'>
+              メール内のリンクを開くとアカウント作成が完了します。
+            </p>
+            <Button type='button' className='w-full' onClick={() => router.push('/auth/login')}>
+              ログインへ
+            </Button>
+          </CardContent>
+        </Card>
+      </div>
+    );
+  }
+
   return (
     <div className='container mx-auto px-4 py-16 flex justify-center'>
       <Card className='w-full max-w-md'>
diff --git a/apps/frontend/app/(public)/auth/reset-password/page.tsx b/apps/frontend/app/(public)/auth/reset-password/page.tsx
new file mode 100644
index 0000000..5d0ac45
--- /dev/null
+++ b/apps/frontend/app/(public)/auth/reset-password/page.tsx
@@ -0,0 +1,120 @@
+'use client';
+
+import Link from 'next/link';
+import { useSearchParams } from 'next/navigation';
+import { Suspense, useState } from 'react';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { Input } from '@/components/ui/input';
+import { useResetPasswordForm } from '@/features/public/auth/reset-password/hooks';
+
+export default function ResetPasswordPage() {
+  return (
+    <Suspense fallback={null}>
+      <ResetPasswordPageContent />
+    </Suspense>
+  );
+}
+
+function ResetPasswordPageContent() {
+  const searchParams = useSearchParams();
+  const token = searchParams.get('token');
+  const linkError = searchParams.get('error');
+  const [completed, setCompleted] = useState(false);
+  const { form, error, validators } = useResetPasswordForm(token, () => {
+    setCompleted(true);
+  });
+
+  if (completed) {
+    return (
+      <div className='container mx-auto px-4 py-16 flex justify-center'>
+        <Card className='w-full max-w-md'>
+          <CardHeader>
+            <CardTitle>パスワードを再設定しました</CardTitle>
+            <CardDescription>新しいパスワードでログインできます</CardDescription>
+          </CardHeader>
+          <CardContent>
+            <Button className='w-full' render={<Link href='/auth/login' />}>
+              ログインへ
+            </Button>
+          </CardContent>
+        </Card>
+      </div>
+    );
+  }
+
+  return (
+    <div className='container mx-auto px-4 py-16 flex justify-center'>
+      <Card className='w-full max-w-md'>
+        <CardHeader>
+          <CardTitle>新しいパスワード</CardTitle>
+          <CardDescription>アカウントに設定する新しいパスワードを入力してください</CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form
+            onSubmit={(e) => {
+              e.preventDefault();
+              form.handleSubmit();
+            }}
+            className='space-y-4'
+          >
+            <form.Field name='password' validators={{ onChange: validators.password }}>
+              {(field) => (
+                <div className='space-y-1'>
+                  <label htmlFor={field.name} className='text-sm font-medium'>
+                    パスワード
+                  </label>
+                  <Input
+                    id={field.name}
+                    type='password'
+                    value={field.state.value}
+                    onBlur={field.handleBlur}
+                    onChange={(e) => field.handleChange(e.target.value)}
+                  />
+                  {field.state.meta.errors[0] && (
+                    <p className='text-sm text-destructive'>{field.state.meta.errors[0].message}</p>
+                  )}
+                </div>
+              )}
+            </form.Field>
+            <form.Field
+              name='confirmPassword'
+              validators={{
+                onChangeListenTo: ['password'],
+                onChange: ({ value, fieldApi }) => {
+                  return validators.confirmPassword({
+                    value,
+                    password: fieldApi.form.getFieldValue('password'),
+                  });
+                },
+              }}
+            >
+              {(field) => (
+                <div className='space-y-1'>
+                  <label htmlFor={field.name} className='text-sm font-medium'>
+                    パスワード（確認）
+                  </label>
+                  <Input
+                    id={field.name}
+                    type='password'
+                    value={field.state.value}
+                    onBlur={field.handleBlur}
+                    onChange={(e) => field.handleChange(e.target.value)}
+                  />
+                  {field.state.meta.errors[0] && (
+                    <p className='text-sm text-destructive'>{field.state.meta.errors[0].message}</p>
+                  )}
+                </div>
+              )}
+            </form.Field>
+            {linkError && <p className='text-sm text-destructive'>再設定リンクが無効です</p>}
+            {error && <p className='text-sm text-destructive'>{error}</p>}
+            <Button type='submit' className='w-full' disabled={form.state.isSubmitting || !token}>
+              {form.state.isSubmitting ? '再設定中...' : 'パスワードを再設定'}
+            </Button>
+          </form>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
diff --git a/apps/frontend/app/(public)/auth/verify-email/page.tsx b/apps/frontend/app/(public)/auth/verify-email/page.tsx
new file mode 100644
index 0000000..f8bc325
--- /dev/null
+++ b/apps/frontend/app/(public)/auth/verify-email/page.tsx
@@ -0,0 +1,40 @@
+'use client';
+
+import Link from 'next/link';
+import { useSearchParams } from 'next/navigation';
+import { Suspense } from 'react';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+
+export default function VerifyEmailPage() {
+  return (
+    <Suspense fallback={null}>
+      <VerifyEmailPageContent />
+    </Suspense>
+  );
+}
+
+function VerifyEmailPageContent() {
+  const searchParams = useSearchParams();
+  const error = searchParams.get('error');
+
+  return (
+    <div className='container mx-auto px-4 py-16 flex justify-center'>
+      <Card className='w-full max-w-md'>
+        <CardHeader>
+          <CardTitle>{error ? '確認リンクが無効です' : 'メールアドレスを確認しました'}</CardTitle>
+          <CardDescription>
+            {error
+              ? 'リンクの有効期限が切れているか、すでに使用されています'
+              : 'DocShare にログインできるようになりました'}
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Button className='w-full' render={<Link href='/auth/login' />}>
+            ログインへ
+          </Button>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
diff --git a/apps/frontend/features/admin/editions/query.ts b/apps/frontend/features/admin/editions/query.ts
index bf5804c..eca168a 100644
--- a/apps/frontend/features/admin/editions/query.ts
+++ b/apps/frontend/features/admin/editions/query.ts
@@ -13,6 +13,7 @@ export function useAdminEditionsList(queryParams: AdminEditionsQueryParams) {
             page: queryParams.page,
             pageSize: queryParams.pageSize,
             q: queryParams.q || undefined,
+            series_id: queryParams.seriesId || undefined,
           },
         },
       });
diff --git a/apps/frontend/features/admin/editions/types.ts b/apps/frontend/features/admin/editions/types.ts
index fda2d96..0d67089 100644
--- a/apps/frontend/features/admin/editions/types.ts
+++ b/apps/frontend/features/admin/editions/types.ts
@@ -33,6 +33,7 @@ export type AdminEditionsQueryParams = {
   page: number;
   pageSize: number;
   q: string;
+  seriesId: string;
 };
 
 export type EditionFormValues = {
diff --git a/apps/frontend/features/public/auth/forgot-password/hooks.ts b/apps/frontend/features/public/auth/forgot-password/hooks.ts
new file mode 100644
index 0000000..a87c18f
--- /dev/null
+++ b/apps/frontend/features/public/auth/forgot-password/hooks.ts
@@ -0,0 +1,34 @@
+import { useForm } from '@tanstack/react-form';
+import { useState } from 'react';
+import { z } from 'zod';
+import { authClient } from '@/lib/auth/client';
+
+export function useForgotPasswordForm(onSuccess: (email: string) => void) {
+  const [error, setError] = useState<string | null>(null);
+
+  const form = useForm({
+    defaultValues: { email: '' },
+    onSubmit: async ({ value }) => {
+      setError(null);
+      const result = await authClient.requestPasswordReset({
+        email: value.email,
+        redirectTo: `${window.location.origin}/auth/reset-password`,
+      });
+
+      if (result.error) {
+        setError(result.error.message ?? 'パスワード再設定メールの送信に失敗しました');
+        return;
+      }
+
+      onSuccess(value.email);
+    },
+  });
+
+  return {
+    form,
+    error,
+    validators: {
+      email: z.string().email('有効なメールアドレスを入力してください'),
+    },
+  };
+}
diff --git a/apps/frontend/features/public/auth/login/hooks.ts b/apps/frontend/features/public/auth/login/hooks.ts
index b80465c..2586967 100644
--- a/apps/frontend/features/public/auth/login/hooks.ts
+++ b/apps/frontend/features/public/auth/login/hooks.ts
@@ -18,6 +18,11 @@ export function useLoginForm(onSuccess: () => void) {
       });
 
       if (result.error) {
+        if (result.error.code === 'EMAIL_NOT_VERIFIED') {
+          setError('メールアドレスの確認が必要です。確認メールを再送信しました。');
+          return;
+        }
+
         setError('メールアドレスまたはパスワードが正しくありません');
         return;
       }
diff --git a/apps/frontend/features/public/auth/register/hooks.ts b/apps/frontend/features/public/auth/register/hooks.ts
index 073c401..d3bad4c 100644
--- a/apps/frontend/features/public/auth/register/hooks.ts
+++ b/apps/frontend/features/public/auth/register/hooks.ts
@@ -4,7 +4,7 @@ import { z } from 'zod';
 import { useInvalidateMe } from '@/contexts/AuthContext';
 import { authClient } from '@/lib/auth/client';
 
-export function useRegisterForm(onSuccess: () => void) {
+export function useRegisterForm(onSuccess: (email: string) => void) {
   const invalidateMe = useInvalidateMe();
   const [error, setError] = useState<string | null>(null);
 
@@ -16,6 +16,7 @@ export function useRegisterForm(onSuccess: () => void) {
         name: value.name,
         email: value.email,
         password: value.password,
+        callbackURL: `${window.location.origin}/auth/verify-email`,
       });
 
       if (result.error) {
@@ -23,8 +24,10 @@ export function useRegisterForm(onSuccess: () => void) {
         return;
       }
 
-      await invalidateMe();
-      onSuccess();
+      if (result.data?.token) {
+        await invalidateMe();
+      }
+      onSuccess(value.email);
     },
   });
 
diff --git a/apps/frontend/features/public/auth/reset-password/hooks.ts b/apps/frontend/features/public/auth/reset-password/hooks.ts
new file mode 100644
index 0000000..9bda83c
--- /dev/null
+++ b/apps/frontend/features/public/auth/reset-password/hooks.ts
@@ -0,0 +1,46 @@
+import { useForm } from '@tanstack/react-form';
+import { useState } from 'react';
+import { z } from 'zod';
+import { authClient } from '@/lib/auth/client';
+
+export function useResetPasswordForm(token: string | null, onSuccess: () => void) {
+  const [error, setError] = useState<string | null>(null);
+
+  const form = useForm({
+    defaultValues: { password: '', confirmPassword: '' },
+    onSubmit: async ({ value }) => {
+      setError(null);
+      if (!token) {
+        setError('再設定リンクが無効です');
+        return;
+      }
+
+      const result = await authClient.resetPassword({
+        newPassword: value.password,
+        token,
+      });
+
+      if (result.error) {
+        setError(result.error.message ?? 'パスワードの再設定に失敗しました');
+        return;
+      }
+
+      onSuccess();
+    },
+  });
+
+  return {
+    form,
+    error,
+    validators: {
+      password: z.string().min(8, 'パスワードは8文字以上で入力してください'),
+      confirmPassword: ({ value, password }: { value: string; password: string }) => {
+        if (value !== password) {
+          return { message: 'パスワードが一致しません' };
+        }
+
+        return undefined;
+      },
+    },
+  };
+}
diff --git a/package.json b/package.json
index 9b0f621..11a2d11 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,7 @@
   "packageManager": "pnpm@10.0.0",
   "scripts": {
     "dev": "dotenv -- pnpm --filter \"./apps/*\" dev",
+    "dev:frontend": "dotenv -- pnpm --filter \"./apps/frontend\" dev",
     "build": "pnpm --filter \"./apps/*\" build",
     "generate:api": "pnpm --filter backend openapi:generate && pnpm --filter frontend generate:api",
     "check": "biome check .",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 9fb39c4..e3cdc89 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -54,6 +54,9 @@ importers:
       hono:
         specifier: ^4.12.9
         version: 4.12.9
+      nodemailer:
+        specifier: ^8.0.5
+        version: 8.0.5
       pg:
         specifier: ^8.13.3
         version: 8.20.0
@@ -64,6 +67,9 @@ importers:
       '@types/node':
         specifier: ^25.5.0
         version: 25.5.0
+      '@types/nodemailer':
+        specifier: ^8.0.0
+        version: 8.0.0
       '@types/pg':
         specifier: ^8.20.0
         version: 8.20.0
@@ -2204,6 +2210,9 @@ packages:
   '@types/node@25.5.0':
     resolution: {integrity: sha512-jp2P3tQMSxWugkCUKLRPVUpGaL5MVFwF8RDuSRztfwgN1wmqJeMSbKlnEtQqU8UrhTmzEmZdu2I6v2dpp7XIxw==}
 
+  '@types/nodemailer@8.0.0':
+    resolution: {integrity: sha512-fyf8jWULsCo0d0BuoQ75i6IeoHs47qcqxWc7yUdUcV0pOZGjUTTOvwdG1PRXUDqN/8A64yQdQdnA2pZgcdi+cA==}
+
   '@types/pg@8.20.0':
     resolution: {integrity: sha512-bEPFOaMAHTEP1EzpvHTbmwR8UsFyHSKsRisLIHVMXnpNefSbGA1bD6CVy+qKjGSqmZqNqBDV2azOBo8TgkcVow==}
 
@@ -3614,6 +3623,10 @@ packages:
   node-releases@2.0.36:
     resolution: {integrity: sha512-TdC8FSgHz8Mwtw9g5L4gR/Sh9XhSP/0DEkQxfEFXOpiul5IiHgHan2VhYYb6agDSfp4KuvltmGApc8HMgUrIkA==}
 
+  nodemailer@8.0.5:
+    resolution: {integrity: sha512-0PF8Yb1yZuQfQbq+5/pZJrtF6WQcjTd5/S4JOHs9PGFxuTqoB/icwuB44pOdURHJbRKX1PPoJZtY7R4VUoCC8w==}
+    engines: {node: '>=6.0.0'}
+
   npm-run-path@4.0.1:
     resolution: {integrity: sha512-S48WzZW777zhNIrn7gxOlISNAqi9ZC/uQFnRdbeIHhZhCA6UqpkOT8T1G7BvfdgP4Er8gF4sUbaS0i7QvIfCWw==}
     engines: {node: '>=8'}
@@ -6611,6 +6624,10 @@ snapshots:
     dependencies:
       undici-types: 7.18.2
 
+  '@types/nodemailer@8.0.0':
+    dependencies:
+      '@types/node': 25.5.0
+
   '@types/pg@8.20.0':
     dependencies:
       '@types/node': 25.5.0
@@ -8005,6 +8022,8 @@ snapshots:
 
   node-releases@2.0.36: {}
 
+  nodemailer@8.0.5: {}
+
   npm-run-path@4.0.1:
     dependencies:
       path-key: 3.1.1