Terms of Service

Last updated: 2026/07/20

Last Updated: March 2026

1. Acceptance of Terms

By downloading, installing, or using this application ("App"), you agree to be bound by these Terms of Service ("Terms"). If you do not agree to these Terms, do not use the App.

This App is an educational and training tool for Japanese mahjong (riichi mahjong). It is not a gambling application: it offers no real-money wagering, no betting, no prizes of monetary value, and no gambling mechanics of any kind.

2. License Grant

Subject to your compliance with these Terms, we grant you a limited, non-exclusive, non-transferable, revocable license to download, install, and use the App on devices you own or control, for your personal, non-commercial use only.

3. Age Requirements and Minors

This App is an educational tool and is open to users of all ages. We collect your date of birth when you register so we can apply the protections appropriate to your age:

Adults (18 and over): full access.
Teens (from the digital-consent age in your region up to 18): access with reduced data collection — no behavioural tracking and no targeted advertising — and no in-app purchases.
Children (below the digital-consent age in your region, for example under 13 in the United States under COPPA): a parent or guardian must give verifiable consent before we use the child's personal information. We collect a guardian email address at registration solely to request that consent and to send the parental notice required by law. Children cannot make in-app purchases.

Parents and guardians may review, refuse, or withdraw consent and request deletion of their child's data at any time. If consent is withdrawn, or is not provided within our grace period, the child's account and associated personal data are deleted. We comply with the Children's Online Privacy Protection Act (US), the child-consent provisions of the GDPR (EU/UK), and Japan's Act on the Protection of Personal Information, as applicable.

4. Account Registration

You must provide accurate, current, and complete information when creating an account.
You are responsible for maintaining the confidentiality of your account credentials.
You are responsible for all activities that occur under your account.
Notify us immediately if you suspect unauthorized access to your account.
We reserve the right to refuse registration or cancel accounts at our discretion.

5. Subscriptions and Payment 5.1 Subscription Plans

Premium features are available through paid subscription. Subscriptions are billed through the Apple App Store (iOS) or Google Play Store (Android) via your platform account. Available plans and current pricing are displayed within the App.

5.2 Automatic Renewal

Subscriptions automatically renew at the end of each billing period unless you cancel at least 24 hours before the renewal date. Your platform account will be charged for renewal within 24 hours before the end of the current period.

5.3 How to Cancel

Cancel your subscription at any time through your platform account settings:

iOS: Settings → [Your Name] → Subscriptions → select this App → Cancel Subscription
Android: Google Play Store → Menu → Subscriptions → select this App → Cancel

Cancellation takes effect at the end of the current billing period. You retain access to premium features until the period ends. We do not provide partial refunds for unused subscription time.

5.4 Free Trials

If a free trial is offered, you will not be charged until the trial period ends. To avoid being charged, cancel before the trial expires. Only one free trial is available per Apple ID or Google account.

5.5 Price Changes

We may change subscription prices. Where required by applicable law, we will provide advance notice of price changes within the App or by email. Continued use of the App after a price change takes effect constitutes your agreement to pay the new price.

5.6 Refunds

Payments are non-refundable except as required by applicable law or the platform's refund policy. For refund requests:

iOS: Visit reportaproblem.apple.com
Android: Contact Google Play support or use the Google Play refund process

EU/UK consumers may have additional rights under applicable consumer protection law; see our Refund Policy for details.

6. Intellectual Property

All content in the App — including but not limited to text, graphics, mahjong tile artwork, question content, educational material, sound effects, user interface design, and software code — is owned by us or our licensors and is protected by copyright, trademark, and other intellectual property laws.

You may not:

Copy, modify, adapt, distribute, or create derivative works from App content
Reverse engineer, decompile, or disassemble the App
Scrape or extract content from the App in bulk
Use our trademarks or branding without written permission
Use App content for commercial purposes without written permission

7. Prohibited Uses

You must not use the App to:

Violate any applicable laws, regulations, or third-party rights
Commit fraud or engage in deceptive practices
Interfere with or disrupt the App's servers, networks, or infrastructure
Attempt unauthorized access to any system, account, or data
Collect or harvest other users' personal information without their consent
Bypass, disable, or circumvent subscription verification or access controls
Upload, transmit, or distribute malware, viruses, or harmful code
Use bots, scripts, or automated tools to access or interact with the App
Engage in any conduct that restricts or inhibits another user's enjoyment of the App

8. User-Submitted Content

You may submit feedback, bug reports, and suggestions through the App. By submitting content:

You grant us a worldwide, royalty-free, perpetual license to use, reproduce, and incorporate that content for service improvement purposes
You represent that your submission does not infringe any third-party rights
You understand we are under no obligation to use or compensate you for your submissions

9. Third-Party Services

The App integrates with third-party services including:

RevenueCat (subscription management)
Sentry (error monitoring and crash reporting)
Firebase / APNs (push notifications)
Apple App Store / Google Play (payment processing, app delivery)

Your use of these services is subject to their respective terms of service and privacy policies. We are not responsible for the practices of third-party services.

10. Service Modifications and Availability

We may modify, suspend, or discontinue any part of the App at any time without notice. We strive to provide reliable service but do not guarantee uninterrupted, error-free access. We are not liable for any modification, suspension, or discontinuation of the App.

11. Account Suspension and Termination

We may suspend or terminate your account with or without notice if:

You violate these Terms
We suspect fraudulent or abusive activity
Required by law or legal process

Upon termination, your license to use the App ends immediately. You may delete your account at any time through Profile → Delete Account. Provisions that by their nature should survive termination will remain in effect.

12. Disclaimers

THE APP IS PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT WARRANTIES OF ANY KIND. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, WE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, AND ACCURACY. WE DO NOT WARRANT THAT THE APP WILL MEET YOUR REQUIREMENTS OR BE ERROR-FREE.

13. Limitation of Liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, WE SHALL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES, INCLUDING LOSS OF DATA OR PROFITS, ARISING FROM YOUR USE OF OR INABILITY TO USE THE APP. OUR TOTAL AGGREGATE LIABILITY FOR ANY CLAIMS ARISING UNDER THESE TERMS SHALL NOT EXCEED THE GREATER OF (A) THE AMOUNTS YOU PAID FOR THE APP IN THE 12 MONTHS PRECEDING THE CLAIM, OR (B) USD 100.

Nothing in these Terms excludes liability that cannot be excluded by law, including liability for death or personal injury caused by negligence, or any applicable statutory consumer rights.

14. Changes to These Terms

We may update these Terms at any time. We will notify you of material changes by posting the updated Terms within the App and updating the "Last Updated" date. Your continued use of the App after changes take effect constitutes acceptance of the updated Terms. If you do not accept the updated Terms, you must stop using the App.

15. Governing Law and Jurisdiction

These Terms are governed by and construed in accordance with the laws of Japan, without regard to conflict of law principles. Any disputes arising under these Terms shall be subject to the exclusive jurisdiction of the court having jurisdiction over our principal place of business in Japan.

If you are a consumer in the EU or EEA, the mandatory consumer protection laws of your country of residence may apply in addition to Japanese law.

16. Contact

For questions about these Terms, please use the in-app feedback feature.