Privacy Policy
How Japanese System handles account, extension sync, analytics, and community visibility data.
Last updated: September 1, 2026
This page is provided for transparency and platform readiness. It is not a substitute for legal advice from a qualified lawyer.
1. Who we are
Japanese System is a Chrome extension and companion website for passive Japanese study tracking. You can contact the operator at sheru.jp@gmail.com.
2. What the service does
The Chrome extension tracks time spent on supported Japanese-learning and immersion sites. If you sign in, synced study history can be shown in your web dashboard, goals, achievements, public profile, leaderboards, and challenges according to your privacy settings.
3. Information we collect
- Account data from Google OAuth through Supabase, such as your email, name, avatar, and authentication identifiers.
- Study-session data synced by the extension, including duration, date, site/category, and other statistics needed to calculate progress.
- Profile settings you choose, including username and privacy toggles for public profile, leaderboard, achievements, and activity visibility.
- Goal, challenge, achievement, and streak-freeze records needed to operate the dashboard and community features.
- Basic technical logs and security information generated by hosting, Supabase, and normal browser requests.
- Optional advertising measurement data if you accept Google Ads cookies.
The website does not collect payment details, passwords, contact lists, precise location data, or website/video titles from your extension. The current product has no billing system.
4. How we use information
- To sign you in and keep your account session secure.
- To calculate study time, streaks, goals, achievements, ranks, leaderboards, and challenge progress.
- To show public profile or community information only when the required privacy toggles are enabled.
- To connect your existing web session to the Chrome extension when you use the extension connect page.
- To debug, secure, maintain, and improve the service.
- To measure Chrome Web Store conversion events when optional Google Ads cookies are accepted.
5. Public sharing controls
Public profile, leaderboard, achievements, category stats, activity, total time, and streak visibility are opt-in controls in your account settings. A public profile does not automatically place you on leaderboards, and leaderboard participation does not reveal raw sessions, timestamps, user IDs, hostnames, or page titles.
6. Cookies and local storage
Japanese System uses essential Supabase authentication cookies when you sign in. A local browser preference stores whether you accepted or rejected optional analytics and advertising cookies.
| Name | Purpose | Duration | Control |
|---|---|---|---|
| Supabase auth cookies | Keep you signed in and refresh your session securely. | Session or persistent, depending on Supabase session settings. | Required for signed-in features. You can clear them by signing out or clearing browser data. |
| japanese-system-cookie-consent | Stores your cookie consent choice in local storage. | Until you clear browser data. | Clear site data in your browser to reset the choice. |
| _ga, _ga_*, _gcl_* | Optional Google measurement and Ads conversion cookies. | Usually up to 2 years, depending on Google's settings. | Reject optional cookies, use Google's opt-out tools, or block cookies in your browser. |
7. Third-party processors
| Provider | Purpose | Data involved |
|---|---|---|
| Supabase | Authentication, database, session cookies. | Account, profile, and synced study data. |
| OAuth sign-in and optional Ads conversion measurement. | OAuth profile data and optional conversion/cookie data. | |
| Vercel | Hosting, deployment, cron execution, and request logs. | Technical request and operational data. |
| YouTube Data API, Netflix public data, TMDB | Public content discovery caches. | No user account or study-session data is sent for these cache refreshes. |
8. Retention and deletion
- Account, profile, goals, challenges, achievements, study sessions, and streak-freeze records are kept while your account exists.
- Deleting your account from the account page deletes your Supabase user and cascades related website records.
- Hosting and security logs may remain for a limited operational period.
- Public content cache data from YouTube, Netflix, and TMDB is not user data and may be refreshed or replaced automatically.
9. Your rights
You may request access, correction, deletion, restriction, portability, or other rights available under applicable privacy laws by emailing sheru.jp@gmail.com. Because the service minimizes public exposure and supports account deletion, some requests can also be handled directly from account settings.
10. International transfers
Your information may be processed in countries where Japanese System, Supabase, Google, Vercel, or their infrastructure providers operate. By using the service, you understand that data may be transferred outside your country subject to applicable safeguards and provider terms.
11. Children
Japanese System is not directed to children under 13, and users in jurisdictions with a higher digital-consent age should use the service only if they meet that requirement or have appropriate consent.
12. Security
The service uses HTTPS, Supabase authentication, database row-level security, and scoped privacy toggles. No online service is perfectly secure, so please contact sheru.jp@gmail.com if you believe your account or data has been affected.
13. Changes and contact
We may update this Privacy Policy as the product changes. The latest version will be posted here with a new last-updated date. Questions and requests can be sent to sheru.jp@gmail.com.