Privacy Policy

Last updated: 22 October 2026

Sumo Japanese (“we”, “us”) is an app for learning Japanese on iOS, Android, the web and desktop. It is made by Anatolii Kataev, an individual developer in Yerevan, Armenia, who is responsible for your data (the data controller). This policy explains what we collect, why, who helps us process it, and the choices you have. Questions: support@sumojapanese.app.

What we collect

• Account: your email address, display name and username, and your password — stored only as a salted Argon2 hash. With Sign in with Apple or Google we receive an identifier from that provider and, if you share it, your email address.
• Learning: lessons and exercises you complete, whether answers were right, XP, your streak, onigiri (hearts), koban (coins) and omamori (streak freezes), achievements, the kana and kanji you have traced, your review schedule, avatar and banzuke (weekly league) results.
• Settings: interface language, daily goal, how much furigana and romaji you want to see, how you type Japanese answers, where you start in the course, reminder time, sound and display choices, and — only if you set one — your weekly rest day. We use these only to run the app the way you choose.
• Social: people you follow, people you block, reports you send, and your place in the weekly banzuke. Your display name, username, avatar, XP, streak, banzuke rank and achievements are visible to other learners.
• Voice (optional): recordings you make in speaking exercises stay on your device unless you turn on automatic pronunciation checking. Then, with Pro, a short recording and the sentence you were reading are sent to our server and to OpenAI to score it; we don’t store recordings, and OpenAI says it keeps API data for at most 30 days (for abuse monitoring) and doesn’t use it to train its models. On the web, automatic checking uses your browser’s built-in speech recognition, which some browsers run on their maker’s servers (Chrome uses Google). You can check yourself by ear instead and switch automatic checking off in Settings at any time.
• Downloads (optional): if you download the course audio for offline use, the audio files of course phrases are stored on your device — in the app’s storage on iOS and Android, or in your browser’s cache on the web and desktop. They contain no personal data and are never uploaded. Delete them at any time in Settings → Offline mode, or by removing the app or clearing the site data.
• Purchases: the App Store, Google Play or Stripe handles payment. We receive the status of your subscription (plan, trial, renewal dates), never your card details. RevenueCat helps us confirm App Store and Google Play subscriptions. When you start the free trial we also record that your email address has used it, as a keyed one-way code (a hash) rather than the address itself, so the trial is offered once per address.
• Device and technical data: your time zone, app version, a push notification token if you allow notifications, and server logs (IP address, time, request) kept for security for up to 30 days.

What we don’t do

• No advertising and no ad networks.
• No tracking across other companies’ apps or websites.
• We don’t sell your personal data or share it for advertising.

How we use it

• To provide Sumo Japanese: save and sync your progress across devices, run the banzuke and friends, and show your profile to other learners.
• To send what you asked for: verification and password-reset codes by email, reminders and notifications you turned on. We also email you when your password is set or changed, so you would notice if someone else did it.
• To process subscriptions and restore purchases.
• To keep Sumo Japanese safe: review reports, remove offensive names or avatars, prevent abuse and fraud (for example, a free trial taken again and again with new accounts).
• To improve the course, using aggregated statistics (for example, which exercises are hardest).

Who processes data for us

Service providers process data only on our instructions and under data-protection terms: our hosting and database provider; our email delivery provider; Apple and Google (sign-in, purchases and delivering push notifications); Expo (push notification service); RevenueCat (store subscriptions); Stripe (web payments); OpenAI (voice scoring, only if you opt in). The course voice is generated in advance and served from our own server, so no other company processes what you listen to.

How long we keep it

We keep your data while you have an account. When you delete your account, we delete your personal data immediately from our live systems and from backups within 30 days. Reports you sent about others are kept without your identity so moderators can finish them. Payment providers keep purchase records as the law requires.

Some records are kept for a shorter time even while you have an account: notifications you have read for 180 days, and records of reminders we sent for 14 days.

The record that an email address has used the free trial (the keyed hash above, not the address) stays after the account is deleted, so that deleting an account and signing up again does not bring a second trial. We keep it for as long as we offer a free trial.

Your choices and rights

• Change your name, username, avatar and settings in the app at any time.
• Delete your account in the app (Profile → Settings → Account → Delete account) or on the web at sumojapanese.app/delete-account. This also removes your data from the banzuke and friends.
• Ask for a copy of your data, or to correct or delete it, by writing to support@sumojapanese.app. Depending on where you live (for example the EU, the UK or California) you may also have the right to object to or restrict processing and to complain to your data-protection authority.
• Turn off notifications and reminders in the app or in your device settings.

Children

Sumo Japanese is for learners aged 13 and over. If you believe a child under 13 has given us personal data, contact us and we will delete it.

Security

Data travels encrypted (HTTPS). Passwords are hashed, sign-in tokens are kept in the device’s secure storage on iOS and Android, and access to our systems is limited to people who need it.

International transfers

Our providers may process data outside your country. Where required, transfers are protected by safeguards such as the EU Standard Contractual Clauses.

Changes

If we change this policy we will update the date above, and tell you in the app before significant changes take effect.

Contact

Sumo Japanese is made by Anatolii Kataev, an individual developer in Yerevan, Armenia. Email support@sumojapanese.app with any question or request about your data.