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Terms of Use

Effective and last updated: September 14, 2026

These Terms of Use (the “Terms”) govern your use of Sakiyomi (the “App”), provided by Koki Tanisaka (the “Developer”). By downloading or using the App, you agree to these Terms. If you’re a user in Japan, the Japanese version of these Terms applies.

1. Scope

  1. These Terms apply to your use of the App and to the Premium Pass, an in-app purchase available in the App.
  2. The App is distributed through the App Store. Anything these Terms don’t cover is governed by Apple’s Licensed Application End User License Agreement (the “Standard EULA”). If these Terms and the Standard EULA conflict, these Terms control as between you and the Developer.

2. Children and Parental Consent

  1. If you’re a minor, a parent or guardian should review these Terms with you and approve any purchase.
  2. Parents can require approval for purchases on a child’s device with Ask to Buy in Family Sharing or with Screen Time.

3. Premium Pass

  1. The Premium Pass is a one-time, non-consumable in-app purchase. It is not a subscription, never renews, and has no recurring charges.
  2. The price is the amount shown on the purchase screen, including any applicable taxes.
  3. Apple processes the payment and charges it to the payment method on your Apple Account. The Developer never receives your payment information.
  4. The Premium Pass features are available as soon as the purchase is complete.
  5. On any device signed in with the same Apple Account, you can reactivate your purchase with Restore Purchases in the App.
  6. The Premium Pass includes the features described on the purchase screen. Features added in future updates are included at no extra charge.
  7. The Developer may change features to improve the App or fix problems, but won’t remove the main features described on the purchase screen without a reasonable cause.

4. Cancellations and Refunds

  1. Because the Premium Pass is digital content, a completed purchase can’t be canceled or returned.
  2. To request a refund, contact Apple at reportaproblem.apple.com. Apple decides refunds under its own policies. The Developer can’t issue refunds directly.
  3. Nothing in this section limits any rights you have under applicable law.

5. Your Data

  1. Your practice records, settings, profiles and other App data are stored only on your device. They are never sent to or stored on the Developer’s servers.
  2. If that data is lost because you delete the App, lose or damage your device, or switch devices, the Developer can’t recover it.
  3. Your Premium Pass purchase is recorded by the App Store separately from that data, so you can always restore it as described in Section 3.5.

6. Prohibited Conduct

You agree not to:

  1. use the App in violation of any law;
  2. modify, decompile, or reverse engineer the App, except as permitted by law;
  3. unlock Premium Pass features without a valid purchase;
  4. sell or redistribute the App or any part of it without the Developer’s permission; or
  5. infringe the rights of the Developer or anyone else.

7. Intellectual Property

  1. All rights in the App, including its code, design, images and text, belong to the Developer or its licensors.
  2. You’re free to share practice report images and practice-settings codes you create in the App.
  3. Worksheets you print with the App may be used for your own or your family’s practice, and handed out to students in lessons or classes. You may not sell them.

8. Disclaimer of Warranties

  1. THE DEVELOPER DOES NOT GUARANTEE ANY PARTICULAR LEARNING RESULT FROM USING THE APP.
  2. THE DEVELOPER WORKS TO FIX PROBLEMS IN THE APP, BUT TO THE EXTENT PERMITTED BY APPLICABLE LAW, THE APP IS PROVIDED “AS IS” AND “AS AVAILABLE,” WITHOUT WARRANTY THAT IT WILL BE ERROR-FREE OR WORK ON EVERY DEVICE OR OPERATING SYSTEM. SUPPORTED DEVICES ARE LISTED ON THE APP STORE.

9. Limitation of Liability

  1. TO THE EXTENT PERMITTED BY APPLICABLE LAW, THE DEVELOPER’S LIABILITY FOR ANY DAMAGES ARISING FROM YOUR USE OF THE APP IS LIMITED TO ORDINARY AND DIRECT DAMAGES ACTUALLY INCURRED, AND WILL NOT EXCEED THE AMOUNT YOU PAID FOR THE APP.
  2. This limitation does not apply to damages caused by the Developer’s willful misconduct or gross negligence. Some jurisdictions don’t allow certain limitations of liability, so parts of this section may not apply to you.

10. Discontinuation

  1. The Developer may stop distributing or supporting the App after giving notice in the App or on the support page.
  2. Even if distribution ends, the Developer won’t disable copies of the App already installed on your device.

11. Changes to These Terms

  1. The Developer may change these Terms when the change benefits users generally, or when it is reasonable in light of the need for the change, the appropriateness of the new terms, and other circumstances, and does not conflict with the purpose of these Terms.
  2. Before a change takes effect, the Developer will post the new Terms and their effective date on this page or in the App.

12. Governing Law and Jurisdiction

  1. These Terms are governed by the laws of Japan. This doesn’t take away any consumer rights you have under the laws of the country or region where you live.
  2. Any dispute about the App will be heard in the first instance by the district court with jurisdiction over the Developer’s address, unless the law of your place of residence requires otherwise.

13. About Apple

  1. These Terms are between you and the Developer, not Apple Inc. The Developer, not Apple, is solely responsible for the App and its content, and for maintenance and support.
  2. Apple Inc. and its subsidiaries are third-party beneficiaries of these Terms. Once you accept these Terms, Apple has the right to enforce them against you as a third-party beneficiary.

14. Contact

Questions about these Terms or the App can be sent to:

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