Privacy Policy
Effective: May 2026
Summary
- We collect only what’s needed to run the app: your email (for account linking), device identifiers (for platform verification), and reading data (for cross-device sync).
- Ads are served by Google AdMob using contextual targeting (based on what you’re reading, not who you are). We do not track you across apps. Subscribing to Sync removes all ads and stops all data sharing with ad providers — unless you explicitly opt in.
- Your sync data is stored on Cloudflare’s global infrastructure. We cannot guarantee data stays in Japan.
- You can delete your account and all associated data at any time from within the app.
- We do not sell your data to anyone.
1. Who We Are
Makura Book is a Japanese web novel reader for iOS and Android, operated by Arseny Teramachi. This policy covers both the Makura Book app and the backend services at makura.kotonoha.ws.
2. Data We Collect
| Data | When | Purpose |
|---|---|---|
| Email address | When you sign in with Google or Apple | Account linking for cross-device sync |
| Device attestation identifier | When setting up sync | Verify the app was installed from a legitimate source (Google Play / App Store) |
| Reading positions and library state | While using sync | Cross-device sync — resume reading where you left off |
| Reading speed | While reading | Optimize content prefetching to your reading pace |
| Subscription receipt | When subscribing | Verify active subscription — processed and discarded, not stored |
3. Data Collected Automatically
| Data | By whom | Purpose |
|---|---|---|
| IP address | Cloudflare (our infrastructure provider) | Network routing, abuse prevention. Retained by Cloudflare for up to 72 hours. |
| IP address, device info, ad interactions | Google AdMob (advertising) | Serve contextual ads relevant to the content you’re reading. We do not request tracking permission (IDFA/ATT) on iOS. |
4. How Ads Work
Makura Book shows ads from Google AdMob. Ads are targeted based on the content you’re currently reading (genre, source URL), not based on your personal profile or activity in other apps. This is contextual targeting — no cross-app tracking is involved.
We do not request iOS App Tracking Transparency (ATT) permission. The iOS advertising identifier (IDFA) is not collected. On Android, the advertising identifier (GAID) may be collected by the AdMob SDK for ad frequency capping.
Subscribing to Makura Book Sync removes all ads.
5. Third Parties
| Service | Role | Data shared |
|---|---|---|
| Cloudflare | Infrastructure (Workers, D1 database, DNS) | All data listed above is processed on Cloudflare infrastructure |
| Google AdMob | Advertising | IP address, device info, ad interaction data, content context (genre/URL) |
| Google / Apple | Authentication, subscription verification | OAuth tokens (authentication), IAP receipts (subscription verification) |
We do not sell, rent, or share your personal data with any other parties.
6. Data Storage and Transfer
Your data is stored on Cloudflare’s globally distributed infrastructure (Workers and D1 database). Data may be processed in any country where Cloudflare operates. We cannot guarantee that data remains within Japan.
Cloudflare maintains Global Cross-Border Privacy Rules (CBPR) certification. All data is encrypted in transit (TLS).
7. Data Retention
- Active subscription: all sync data is retained for the duration of your subscription.
- After subscription lapses: data is retained for 6 months. After this period, your sync identity and all associated data are permanently deleted.
- Account deletion: when you delete your account through the app, all server-side data (sync identity, linked accounts, device records, sync data) is deleted immediately and permanently. Store-side billing data (managed by Google/Apple) is not affected.
8. Your Rights
- Delete your data: you can delete your account and all associated data at any time from within the app.
- Access your data: your reading positions and library state are visible in the app. If you need a data export, contact us.
- Opt out of personalized ads: ads in Makura Book are already contextual (not personalized). No opt-out is needed.
9. 利用目的の公表 (Disclosure of Purpose of Use)
個人情報保護法に基づき、個人情報の利用目的を以下に公表します。
- メールアドレス: クロスデバイス同期のためのアカウント識別
- 端末識別子: アプリの正当性検証
- 読書データ: 端末間での読書進捗・ライブラリの同期
- コンテンツ情報（ジャンル、作品URL）: 関連性の高い広告の表示
10. Children
Makura Book is not directed at children under 13. We do not knowingly collect personal information from children.
11. Changes
We may update this policy. Material changes will be communicated through the app. The effective date at the top of this page always reflects the latest version.
12. Contact
For privacy-related questions or data requests: apps@kotonoha.ws