Privacy Policy

This Privacy Policy explains how 影追い (“Yasashii”) — a personal, non-commercial Japanese graded-reading and shadowing study app available at yasashii.sirius.cool (the “Service”) — collects, uses, and protects your information. The Service is operated by an individual (“we”, “us”). If you do not agree with this policy, please do not use the Service.

1. Information we collect

Account information (via Google Sign-In)

When you sign in, Google provides us with your email address and basic profile information (such as your name and profile picture) associated with your Google Account. We use and store only your email address, which serves as the identifier for your account. We do not receive or store your Google password.

Learning data you create

While you use the Service, we store the study data you generate, keyed to your account:

• Reading progress (which articles or stories you have read).
• Your vocabulary word bank and its spaced-repetition review schedule.
• Practice sentences you save and their review history.
• Community notes you choose to submit on study content.
• Counts of AI-feature usage (used for rate-limiting).

Authentication cookie

To keep you signed in, we set a single HttpOnly, Secure session cookie (yz_session). It is essential to the Service’s operation. We do not use advertising or third-party tracking cookies.

AI-feature input

When you use an AI-powered feature (such as an on-demand dictionary explanation), the Japanese text you select or submit is sent to an AI model provider (Google Gemini API and/or a self-hosted model) to generate a response. Please do not enter sensitive personal information into these features.

Technical logs

Like most websites, our hosting and content-delivery providers automatically record standard technical information (such as IP address, browser type, and request timestamps) for security, abuse prevention, and reliability.

2. How we use your information

• To authenticate you and maintain your signed-in session.
• To save and synchronize your learning progress across your devices.
• To generate AI explanations you request.
• To moderate community notes (automated) and enforce fair-use rate limits.
• To operate, secure, and maintain the Service.

3. How we share information

We do not sell your personal information, and we do not use it for advertising. We share information only as needed to run the Service:

• Google — for sign-in (authentication).
• Cloudflare — for hosting, content delivery, and network security.
• AI model provider (Google Gemini API) — receives only the text you submit to an AI feature, in order to return a result.
• Other users — community notes you submit may be displayed publicly to other users after automated moderation. Do not include personal information in them.

We may also disclose information if required by law or to protect the Service from abuse.

4. Google user data

The Service’s use of information received from Google APIs adheres to the Google API Services User Data Policy, including its Limited Use requirements. Specifically: we request only your basic profile and email; we use your email solely to identify your account and provide the Service; we do not sell it; and we do not share it except as described above. You can revoke the Service’s access at any time from your Google Account permissions page.

5. Data retention and deletion

We retain your account and learning data for as long as your account is active. You may request deletion of your account and associated data at any time by emailing [email protected]; we will delete it within a reasonable period.

6. Your rights

You may request access to, correction of, or deletion of your personal data by contacting us at [email protected]. You can also sign out at any time and revoke Google access as described above.

7. Security

We protect data in transit with HTTPS, store the session token in an HttpOnly cookie, and keep copyrighted third-party content restricted. No method of transmission or storage is perfectly secure, but we take reasonable measures to protect your information.

8. Children

The Service is not directed to children under 13, and we do not knowingly collect personal information from them.

9. Changes to this policy

We may update this policy from time to time. Material changes will be reflected by an updated “Last updated” date at the top of this page.

10. Contact

Questions about this policy? Email [email protected].