SHUTOKU Privacy policy

What Shutoku stores, and what it does not.

Last updated 7 August 2026

Shutoku is a Japanese study app published by Systems Atlas Project Limited. This policy explains what the app collects, why, who it is shared with, and how to get rid of it. It covers the Shutoku app on Android and iOS.

The short version

Shutoku requires a free account. That means an email address and a password.
Your study progress — which cards you have reviewed, when each is next due, and your daily streaks — is stored in your account so it follows you between devices.
There is no advertising, no analytics and no tracking of any kind. No advertising ID is collected and no third-party analytics or crash-reporting service is built into the app.
Nothing is sold, and nothing is shared for advertising.
If you use translation practice, the text you type is sent to OpenAI to generate the reply. It is the only feature that does this.
You can delete your account and everything in it from inside the app, or by email. See account deletion.

What is collected, and why

Email address

Required. It identifies your account and is the address a password-reset link is sent to. Stored with your password, which is hashed with bcrypt and never stored or transmitted in a readable form.

Study progress

Required. For each card: how many times you have reviewed it, its current interval and ease factor, when it is next due, and whether you have seen it. Also your per-deck daily completions, which is what streaks are calculated from, and your best conjugation-practice streak.

This is uploaded automatically when you create an account and downloaded automatically when you sign in — that is how your progress reaches a new device.

Translation practice text

Optional — only if you use that feature. What you type, and the conversation so far, is sent to our server, which passes it to OpenAI to generate a reply. See third parties below.

Feedback and reports

Optional. If you send feedback, or report an AI-generated reply, the message is emailed to us. A reported reply is attached to the report so we can see what you are reporting. Including your email address so we can answer is a choice you make each time, and it is off by default.

What is not collected

No advertising ID, and no advertising of any kind.
No analytics and no crash reporting. The app contains no such library.
No location. The app does not request location permission and contains no location code.
No contacts, calendar, photos, files, camera or microphone. The app requests only two permissions — internet access and network state.
No payment information. Shutoku is free and has no in-app purchases or subscriptions.
No browsing history and no list of your other apps.

Third parties

Two, and only two. Neither is an advertiser and neither receives your data for their own marketing.

OpenAI — translation practice only

When you use translation practice, the sentence you type and the conversation so far are sent from our server to OpenAI to generate a reply. Your email address and account identifier are not sent with it. OpenAI processes and retains that request under its own terms, which we do not control. Nothing else in the app sends anything to OpenAI, and the rest of Shutoku works entirely without it.

Resend — outbound email

Password-reset emails, feedback and AI-response reports are delivered through Resend. If you include your email address with a report, it is in that email.

Hosting

The Shutoku server and its database are hosted on Railway. Your account and progress are stored there.

How your data is protected

Everything between the app and our server travels over HTTPS. The app has no cleartext network path.
Passwords are hashed with bcrypt. We cannot read your password, and neither can anyone who obtains the database.
Your sign-in token is stored in the device's encrypted storage — the Android Keystore-backed encrypted preferences, or the iOS Keychain.
Signing out deletes the app's data from that device. The app asks first whether you want to upload before signing out. Your account keeps whatever was last uploaded.

How long it is kept

Your account and progress are kept until you delete them. Deletion is immediate and removes your account row and every review state and streak record attached to it.

Two things sit outside that, and we would rather say so than imply otherwise: feedback or reports you have already sent us exist as emails in our inbox, and translation-practice text already sent to OpenAI is retained by OpenAI under its terms. Neither is linked to your account.

Your choices and rights

Delete everything — in the app, Settings → Account → Delete account, or by email. See account deletion.
Get a copy — email us and we will send you what your account holds.
Correct your email address, or ask any question about this policy, by email.
Avoid the OpenAI transfer entirely by not using translation practice. Every other feature works without it.

If you are in the UK or EU, we process your email address and progress to provide the app you asked for, and we rely on that contractual necessity as our lawful basis. You may complain to the UK Information Commissioner's Office if you believe we have handled your data improperly.

Children

Shutoku is a study app suitable for general audiences and is not directed at children under 13. We do not knowingly collect data from children under 13. If you believe a child has created an account, email us and we will delete it.

Changes

If this policy changes materially, the date at the top changes and the app's store listing is updated. Continued use after a change means the new version applies.

Contact

Systems Atlas Project Limited
shutoku@systemsatlasproject.com

Shutoku is published by Systems Atlas Project Limited. Delete your account.