Privacy Policy

Deshi Mate — Japanese learning app by Void Realm Solutions.
Effective date: 3 September 2026. Contact: [email protected]

1. Who we are

Deshi Mate is published by Void Realm Solutions ("we", "us"). This policy covers the Deshi Mate Android app and the deshimate.app website. It applies to everyone who uses the app.

2. What we collect and why

Account information (required). To create an account you provide an email address and password, or sign in with Google. Firebase Authentication (Google) stores your email address, an internal user ID, and the sign-in method. If you sign in with Google we receive your Google account's email address and a basic profile (name and picture) as part of the Google sign-in; we use the email address only.

Learning progress (required for the app to work). Your study state is saved to our cloud database so that it syncs across your devices: your chosen display name and target JLPT level; per-card review history (which items you studied, when, how often you got them right, and the spaced-repetition scheduling values that decide when you see them next); skill mastery estimates; your experience points, streak, and per-game totals; and your device time zone and preferred "day boundary" hour so streaks are calculated correctly. Each device also stores an anonymous random identifier so we can merge progress from several devices without double-counting. None of this includes the content of anything you type beyond the answers you give in the games.

Usage analytics and crash reports (optional, off by default). If you turn on "Help improve Deshi Mate" at sign-up or later in Settings, we use Google Analytics for Firebase and Firebase Crashlytics to collect: app open/close, which game you completed, sign-up funnel steps, a flag for whether your device has a Japanese text-to-speech voice installed, crash stack traces, and device/OS model information. These are linked to a random app-instance ID and, while you are signed in, to your account ID. You can turn this off at any time in Settings; turning it off stops collection immediately and clears the analytics data held on the device.

Security signals. The app uses Firebase App Check with Google Play Integrity to confirm requests come from a genuine copy of Deshi Mate. This sends an attestation token to Google; it does not identify you personally.

We do not collect your location, contacts, photos, microphone audio, or advertising identifiers. Deshi Mate does not contain advertising.

3. How we use your data

• To operate the app: authenticate you, sync your progress, and schedule your reviews.
• To keep your account secure and prevent abuse of our services.
• If you opted in: to understand which features are used and to fix crashes.
• To respond when you contact us.

We do not use your data for advertising, do not sell it, and do not share it with third parties except the service providers listed below.

4. Where your data lives and who processes it

We use Google Firebase (Google LLC) for authentication, the cloud database (Cloud Firestore), App Check, and — only if you opt in — Analytics and Crashlytics. Google processes this data on our behalf under the Firebase Data Processing Terms. Data is stored in Google Cloud data centres; it may be processed in the United States.

Data is encrypted in transit (TLS) between the app and Google's servers, and encrypted at rest by Google Cloud.

On your device, Deshi Mate keeps a local copy of your progress so the app works offline. This local database is stored in the app's private storage, which Android isolates from other apps, but it is not separately encrypted by Deshi Mate. If you use a shared or unlocked device, anyone with access to it can use the app as you until you sign out.

5. How long we keep it

• Account and progress data: for as long as your account exists.
• Analytics data (if opted in): Google Analytics retains user-level data for 2 months; aggregated reports may be kept longer. Crash reports are kept for 90 days.
• After you delete your account: everything listed above is deleted (see section 6). We keep only a minimal record that the deletion happened, with no personal data, so the account cannot be accidentally restored.

6. Deleting your account and data

You can delete your account from inside the app: Settings → Account → Delete account. This immediately erases your cloud progress, deletes your sign-in account, and wipes all data on the device. Other devices signed in to the account wipe themselves the next time they go online. If you no longer have access to the app, you can request deletion by email — see deshimate.app/delete-account for the steps.

You can also reset your learning progress without deleting your account (Settings → Reset progress), and turn analytics on or off at any time (Settings → Help improve Deshi Mate).

7. Your rights

Depending on where you live (for example under the GDPR in the EU/UK or the CCPA in California) you may have the right to access, correct, export, or delete your personal data, to object to or restrict certain processing, and to complain to a supervisory authority. Deletion and analytics opt-out are built into the app; for anything else, email [email protected] and we will respond within 30 days. We may need to verify that a request comes from the account owner.

8. Children

Deshi Mate is intended for users aged 13 and over and is not directed at children. We do not knowingly collect personal data from children under 13 (or the applicable age in your country). If you believe a child has created an account, contact us and we will delete it.

9. Changes to this policy

If we make material changes we will show a notice in the app and update the effective date above. Continuing to use Deshi Mate after a change means you accept the updated policy.

10. Contact

Void Realm Solutions — [email protected]. Account deletion requests: [email protected].