Privacy Policy

Last updated: September 3, 2026

Tsuzuku (the "Service") is an app and website (tsuzuku.app) operated by Kotaro Okuda (the "Operator") that turns your diary into manga. This policy explains what information the Service handles and how.

1. Information we collect

Diary content: the text, photos, and video you record, and the manga generated from them (if you dictate, what your device transcribes is kept as diary text; the audio itself is not stored)
Protagonist setup: a face photo you may optionally register
Account information: an anonymous user ID; if you sign in with Apple or Google for data transfer, the linked identifier
Purchase information: your in-app purchase history via Apple (the Operator never receives credit card numbers or other payment details)
Notification token: the device token needed to deliver push notifications
Usage data: behavioral events such as screens viewed and features used (never the content of your diary — no text, photos, audio, or video)
Technical information: access logs kept to operate the Service

2. How we use it

Providing the Service, above all generating your manga
Tsu's replies, shaping your entries into a story, and checking a draft before it goes out
Managing purchases and credits, delivering notifications
Analyzing usage to improve the Service
Preventing abuse, improving quality, and responding to inquiries

3. AI processing

The Service sends your diary to Google's generative AI (the Gemini API) for processing. What is sent: the text, photos, and videos you record in your diary, plus the protagonist face photo if you choose to register one. The app explains this and asks for your consent before any of it happens for the first time, and you can withdraw that consent in the app at any time.

It is used for the following, and nothing else:

Tsu's replies
Shaping your entries into a story (storyboard and synopsis)
Drafting and drawing your manga
Checking a draft before it goes out (quality and safety review)

As a rule the Operator's server (Supabase Edge Functions) passes the request along. Video is the exception: it is uploaded from your device straight to Google's file API, and is deleted from Google once the transcription is done. The video itself is never stored on the Operator's servers.

Voice input is transcribed by your device's operating system (Apple's speech recognition on iOS), not by Google. Only the resulting text, once it is in your diary, ever reaches the AI.

The Operator never sells your content, nor shares it with third parties for advertising purposes.

Google handles this data solely as the Operator's processor, under the paid Gemini API terms. Content you send is not used to train Google's models, and it is not retained beyond what processing requires. The Operator has confirmed that these terms provide protection equal to this policy.

4. Publishing and sharing

When you set an issue to "link-only" or "public", people with the link — or everyone — can read it. You can change or withdraw publication at any time. The "read" seals pressed by readers are counted anonymously, and only the count reaches the author.

5. Third-party processors

Supabase (database and storage)
Cloudflare (hosting and bot protection)
Google (generative AI — the Gemini API, push notifications, sign-in)
Apple (sign-in, in-app purchases)
RevenueCat (purchase management)

6. Storage and deletion

You can delete diary entries and manga in the app at any time. You can request deletion of your account and all data from the in-app settings or via the contact below; we delete it within a reasonable period. Backups kept for disaster recovery are purged on a rolling basis after deletion.

7. Tracking

The Service shows no behavioral advertising and does not track you across apps or websites.

8. Children

If you are under 13, please use the Service with a parent or guardian's consent.

9. Changes

This policy may be revised as needed. We will announce significant changes on the Service.

10. Contact

Operator: Kotaro Okuda
Contact: support@tsuzuku.app