Legal, Privacy & Attributions

By using Mastermind Japanese, you agree to use the service for personal, non-commercial language learning. You are responsible for keeping your account credentials secure. You agree not to abuse, reverse-engineer, scrape, or attack the service. We reserve the right to suspend or terminate accounts that violate these terms. These terms may be updated at any time; continued use after changes constitutes acceptance.

To the fullest extent permitted by law, Mastermind Japanese and Jason Kobayashi shall not be liable for any indirect, incidental, or consequential damages arising from your use of the service. Total liability for direct damages is limited to the amount you have paid for the service (currently $0 during the free beta).

These terms are governed by the laws of Japan. Any disputes shall be subject to the exclusive jurisdiction of the courts of Tokyo, Japan, without prejudice to any mandatory consumer protection rights in your country of residence.

Data controller: Jason Kobayashi, Tokyo, Japan. Contact: jason@jasonkobayashi.com

We collect limited data needed to provide and protect the study experience:

• Email address (for login and service-related notifications). Optional password (stored hashed, never in plain text). Study progress (concept states, session history, grades, bookmarks). Server logs (IP address, user agent, timestamps) for security and service operation.
• The optional email newsletter is separate from service emails and requires your explicit consent. You can unsubscribe at any time via the link in any newsletter email or through Settings. Service emails (login links, security notices) are necessary for your account and are not marketing.
• Data is stored in PostgreSQL hosted on Render (US-based). If you are located outside the US, your data is transferred to the US for processing. Authentication tokens are stored in your browser's localStorage for session persistence. No cookies are used for tracking or advertising.
• We do not use third-party analytics, advertising trackers, or cross-site tracking of any kind.

We process your data on the following bases: account and study features (necessary to provide the service you requested), security logs (our legitimate interest in protecting the service), newsletter (your consent, withdrawable at any time).

We use the following service providers to operate: Render (US) for hosting and database, Resend for transactional and newsletter email delivery. We do not send your account data or study progress to AI providers.

We keep your account and study data while your account is active. Server logs are retained for up to 30 days. Backups may persist for up to 14 days after deletion. Newsletter unsubscribe records are retained as needed to honor your preference. You may request deletion of your account and data at any time by contacting us.

You have the right to access, correct, delete, restrict processing of, object to processing of, and request portability of your personal data. You may withdraw consent for the newsletter at any time. You have the right to lodge a complaint with a supervisory authority in your country. We aim to respond to data requests within 30 days. To request data export or account deletion, contact us at the email below.

We use browser localStorage to keep you signed in. This is necessary for authentication and is not used for advertising, analytics, or cross-site tracking. You can clear it by signing out or clearing your browser data.

We use reasonable safeguards to protect your data, including hashed passwords, access controls, and encrypted connections (HTTPS). No system is perfectly secure, and we cannot guarantee absolute security.

For privacy questions, data requests, or to report a concern: jason@jasonkobayashi.com