Terms of Service

Article 1 (Scope)

These Terms apply to all matters concerning the use of the App between the provider of the App (hereinafter "we," "us," or "the Operator") and users.

The App is provided for users in the countries and regions where we make it available on each app store. We do not warrant that use of the App from any other country or region complies with the laws of that country or region.

Article 2 (Accounts)

Your account in the App is anonymous and is tied to the browser storage (localStorage) of this device. If that storage is lost — for example, when browser data is cleared, the App is uninstalled, the device is reset, or a private browsing session ends — there is no way to restore the same account. Your game history, skill estimate, achievements, and online rating will all be lost. A feature for carrying an account over to another device is not currently offered.

The App does not ask you to register your name, email address, phone number, or similar information. Only when you use online player-versus-player matches, an identifier (UUID) generated automatically for each device, your display name, and the identifier of the avatar you selected are stored on the server. The display name you set on the Profile screen (1–12 characters) is sent to the server and stored there; if you have not set one, a provisional display name assigned automatically by the server (for example, "Player#4821") is used. See the Privacy Policy for details.

Your display name and avatar are shown to other users, namely to your opponents and on the leaderboard. Do not include in your display name any information that could identify you personally, such as your name or contact details, any expression that impersonates another person or the operator, or any expression that other users may find offensive. If a display name is inappropriate, we may reset it on the server to a provisional display name, based on a report from another user (which can be made from the game screen) or on a message to our contact address. While that is in effect, you will be unable to change your display name for a period of time.

Article 3 (Age Requirement)

The App is intended for users aged 13 and over. If you are under 13, please do not use the App. Minors should use the App with the consent of a parent or guardian.

We do not collect dates of birth or any other age-related information.

Article 4 (Prohibited Conduct)

When using the App, you must not engage in any of the following conduct:

1. Improperly manipulating game results, ratings, leaderboards, or achievements, including by altering network traffic, rewriting stored data, submitting false reports to the server, or deliberately arranging wins and losses using multiple accounts (so-called collusion or self-play).
2. Reverse engineering, decompiling, disassembling, or otherwise analyzing or modifying the source code of the App, except to the extent that such acts are expressly permitted by applicable law.
3. Playing online matches using bots, scripts, external game engines, or other automated tools, or having any non-human agent play on your behalf.
4. Sending requests to the match server, the AI review feature, or any other server feature at a frequency far exceeding normal use, or accessing them for the purpose of load testing or penetration testing.
5. Exploiting vulnerabilities in the App, or attempting to circumvent authentication or access controls.
6. Using discriminatory, obscene, or violent expressions, or expressions that infringe the rights of others.
7. Infringing the copyrights, trademarks, or other rights of other users, third parties, or the Operator.
8. Copying, distributing, lending, redistributing, or commercially exploiting all or any part of the App without our permission.
9. Violating laws or public order and morals, or engaging in conduct connected with criminal activity.
10. Any other conduct that we reasonably determine to be inappropriate.

If we determine that you have violated the preceding paragraph, we may, without prior notice, correct your rating or match records, suspend your access to online matches, or take any other measures we consider necessary.

Article 5 (Provision, Modification, and Suspension of the Service)

We may modify the content of the App, or suspend or terminate its provision, without prior notice.

Within the App, games against the on-device AI work offline. Online player-versus-player matches, leaderboards, and AI reviews, on the other hand, require a network connection and our servers, and may be unavailable due to maintenance, outages, or network conditions.

Article 6 (Intellectual Property and Trademarks)

All rights in the App and in the programs, images, audio, and text contained in it belong to the Operator or to their respective rightful owners.

The App is based on Reversi, a board game played on an 8×8 board in which discs are captured by flanking them. Certain other names for this game are registered trademarks of third parties, and we do not use any of those names in the title, descriptions, or in-app displays of the App. We have no capital or partnership relationship with the owners of those trademarks.

Article 7 (Fees)

The App is free to use, and games against every level remain available at no charge. We also offer optional paid features (Premium); buying them removes advertisements. Premium is sold either as a one-time purchase (a single payment that does not renew) or as a subscription (which renews automatically). Which of the two is offered depends on the app store you use, and the purchase screen shows the price together with the billing period when the item is a subscription. In addition, we sell cosmetic items, such as animated avatars shown on the game screen, as one-time purchases. Cosmetic items change appearance only and have no effect on playing strength or the rules of the game. AI reviews of your games are available without buying Premium. Within your record, the skill analysis (radar chart) and its AI-generated overall assessment are Premium features. The lines your opponent speaks during a game (“The AI’s thoughts”) are available whether or not you buy Premium. Playing strength and the rules of the game are the same either way. Premium and cosmetic items are purchased on the purchase screen within the App (billed through the App Store / Google Play). Prices, billing periods, and payment methods are displayed, inclusive of tax, on each app store's product page and on the purchase screen within the App.

Purchase and payment for Premium and for cosmetic items are handled through each app store’s billing system. Where Premium is offered as a subscription, cancellation is handled through the same system (the subscription settings on your device); one-time purchases do not renew, so there is nothing to cancel. We never receive your credit card number or any other payment details.

Without buying Premium, you can still play against every level, view your statistics (except the skill analysis), earn achievements, play online player-versus-player matches, use AI-generated reviews, and hear “The AI’s thoughts” during a game. We do not hold the game itself hostage.

Article 8 (Disclaimer)

1. We do not warrant that the App will suit your particular purpose, that it will have the functionality, accuracy, or usefulness you expect, or that it will be free of defects.
2. We are not liable for any damage you incur through use of the App, except where such damage results from our willful misconduct or gross negligence.
3. We are not responsible for recovering game history, settings, or achievements stored on your device that are lost due to device failure, clearing of browser data, uninstallation of the App, operating system updates, insufficient storage, or any other cause. We do not provide a backup feature for this data.
4. AI-generated post-game reviews are text produced automatically by a generative AI (Google Gemini), and we do not warrant their accuracy or soundness. Please treat them as reference information only.
5. We are not responsible for the conduct of other users in online matches. Disputes between users must be resolved between the parties concerned.
6. Offline operation of the App relies on the content stored on your device. We do not warrant that alternative means will be provided when features requiring a network connection are unavailable.

Article 9 (Handling of Personal Information)

The handling of information in the App is governed by our separately published Privacy Policy. The Privacy Policy forms part of these Terms.

Article 10 (Governing Law and Jurisdiction)

These Terms shall be governed by and construed in accordance with the laws of Japan.

Any dispute arising between the Operator and a user in connection with the App shall be subject to the exclusive jurisdiction of the Japanese court having jurisdiction over the location of the Operator as the court of first instance.

Article 11 (Changes to These Terms)

We may change these Terms when we consider it necessary, without individually notifying users. The revised Terms take effect from the time they are posted on this page.

When we make a material change, we will display the details of the change and its effective date at the top of this page for a certain period. If you use the App after a change, you are deemed to have agreed to the revised Terms.

Article 12 (Contact)

For inquiries about these Terms, please contact us through the channel listed on the Contact page.