Privacy Policy

Last updated: 18 May 2026

Tsumihon is a personal library manager for doujinshi and manga. We designed it to keep almost everything on your device. This page explains what data Tsumihon handles, where it goes, and the choices you have.

If you have questions, write to support@tsumihon.app.

What Tsumihon is

Tsumihon is a collection and reading app you install on your mobile or tablet device. It catalogs books you own or have added, fetches metadata and cover art from public sources, and shows them in a built-in reader. We do not sell, distribute, or host any of the books or images themselves.

Tsumihon is intended for adults. Some content surfaced through external catalog sources is not appropriate for minors.

Your account

Using Tsumihon requires a Tsumihon account. The account is what powers cross-device sync, lets you restore your library on a new device, and ties your in-app purchases to a persistent identity.

When you create an account we collect:

• An email address.
• An authentication credential (for example, a hashed password or an identity-provider token, depending on how you sign in).

We use this information to authenticate you, deliver service-related messages, and let you recover your account.

You can delete your account from the app’s settings. Deletion removes your synced library and account record from our backend. The local copy on your device stays there until you reset the app.

Data stored on your device

When you use Tsumihon, the following data lives on your device only:

• Your library: book titles, authors, tags, ratings, reading progress, notes.
• Cover thumbnails and any downloaded files you cache for offline reading.
• Settings: theme, reading direction, source preferences, app-lock state.
• Session credentials you add yourself for external catalog sources you choose to log into. These are stored locally and only sent to the source they belong to.

You can clear any of this from the app’s settings at any time.

Cloud sync

Your library metadata and settings sync to our backend so they appear on your other devices when you sign in. The synced record contains:

• Library metadata (titles, tags, progress, notes, etc.).
• App settings.
• Your account email and authentication state.

We do not sync:

• Downloaded book files or cover images.
• Session credentials for external catalog sources.
• Analytics or diagnostic data.

Our backend runs on a managed cloud platform under a data-processing agreement that restricts the provider’s use of your data to operating the service for us. We may change providers as the service evolves; we will continue to apply equivalent protections.

Analytics

To understand which features are used so we can prioritize what to build, Tsumihon can send anonymous product-analytics events. These events:

• Are anonymous and contain no library titles, tags, authors, or other content from your collection.
• Do not include personally identifiable information.
• Are not used for advertising or cross-site tracking.

You can opt out at any time — during onboarding or later in the app’s settings. When opt-out is on, no analytics events are sent.

Crash and error reports

If the app crashes or hits an unexpected error, we may receive an anonymized stack trace so we can fix the bug. Reports include device model, OS version, and the crashing code path. They do not include your library, your account, or any content you opened.

Optional AI features

Some features — for example, extracting text from a cover photo — are off by default and require you to provide a credential for an external AI provider of your choice. When you enable such a feature and explicitly trigger it, the single image or text you selected is sent from your device directly to that provider. We do not proxy or store the credential, and we do not receive the image.

The provider’s handling of your request is governed by their terms — read them before enabling a feature that uses an external provider.

Purchases

If you buy Tsumihon or an in-app subscription, purchases are processed by the platform you installed Tsumihon from (the device’s app store). We do not see your payment details. We do receive a confirmation that your account is entitled to the features you bought, so we can unlock them across your devices.

External catalog sources

Tsumihon can query public catalog sources you choose to enable. These requests go directly from your device to the source — they do not pass through our servers. If you log in to a source, the session credentials are stored locally on your device and only sent back to that source.

We are not affiliated with any catalog source, do not control them, and have no insight into their data practices. Review their terms before using them.

Children

Tsumihon is not directed at, and not appropriate for, anyone under 18. Some catalog sources surface adult content. Do not use Tsumihon if you are a minor.

Your rights

You can, at any time:

• See what’s stored locally — everything is visible in the app’s library and settings screens.
• Export your library — use the backup feature in the app’s settings.
• Sign out — drops account state from the device.
• Delete your account — removes the synced copy from our backend.
• Reset the app — wipes all local data.
• Opt out of analytics — toggle in onboarding and settings.

If you’d like a copy of any data we hold about you, or want it deleted, email support@tsumihon.app from the address tied to your account.

Changes to this policy

If we make material changes, we will update the date at the top of this page and, where appropriate, surface a notice in the app. Continued use after a change means you accept the updated policy.

Contact

Questions, concerns, or requests:

• Email: support@tsumihon.app