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. When you take part in online player-versus-player matches, an identifier (UUID) generated automatically for each device, an anonymous display name assigned automatically by the server (for example, "Player#4821"), and the identifier of the avatar you selected are stored on the server. Even if you never play a match, purchasing or restoring a paid plan issues an anonymous account, and your identifier, the display name assigned automatically by the server, and your purchase status are stored on the server. Using the AI features (the summary or an AI review) likewise records an identifier on the server for rate-limiting purposes. The display name you enter on the Profile screen is sent to and stored on the server when you take part in online player-versus-player matches, and it is shown to your opponents and on the leaderboard (if you have not set one, the anonymous display name assigned automatically by the server is used instead). See the Privacy Policy for details.

Opponents and leaderboards display the name you set on the Profile screen (or, if you have not set one, the anonymous display name assigned automatically by the server). Because your display name is visible to other users, do not set anything that identifies an individual — such as a real name, address, or contact details — anything that impersonates someone else, or anything contrary to public order and morals. Display names of that kind may be reset to an anonymous display name without notice, based on reports from other users.

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 chess, a board game played on an 8×8 board in which the object is to checkmate the opponent’s king. Chess itself, and its name, are in the public domain and belong to no particular rights holder. We have no capital or partnership relationship with the makers of any existing chess engine or chess service, and we do not use their names or trademarks in the title, descriptions, or in-app displays of the App. Names of real historical figures and campaigns, including Napoleon Bonaparte, are used as references to recorded history and do not imply any endorsement or affiliation.

Article 7 (Fees)

The App is free to use, and every game feature remains available at no charge. We also sell an optional paid plan (Premium) as a one-time purchase; buying it removes advertisements. We do not offer any monthly or annual 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 purchasing the paid plan. Within your record, the skill analysis (radar chart) and its AI-generated overall assessment are features of the paid plan. The paid plan and cosmetic items can be purchased only in the app versions (App Store / Google Play) and cannot be purchased in the browser version. 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 the paid plan are handled through each app store’s billing system. We never receive your credit card number or any other payment details.

Without purchasing the paid plan, you can still play against every level, view your statistics (except the skill analysis), earn achievements, play online player-versus-player matches, and use AI-generated reviews. We do not hold the game itself hostage.

Coins in the app are granted by us for watching rewarded ads or based on match results, and can be used only to unlock cosmetic items in the app (piece styles, boards, and avatar frames). Coins are stored only on your device, have no monetary value, and cannot be exchanged for cash, transferred, moved to another device, or refunded. Coins are never required to purchase the paid plan or to play. If coins are lost because you change devices, delete the app, or delete saved data, we will not restore them. We may change the conditions for granting coins and what they can be used for, or discontinue them, without prior notice.

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, achievements, or coins 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.