Terms of Service

These Terms of Service (hereinafter, the "Terms") set forth the conditions for using the Chrome extension "Fu-Sen" and its associated servers and website (hereinafter collectively, the "Service") provided by the operator of Fu-Sen (hereinafter, the "Operator"). Users of the Service (hereinafter, "Users") may use the Service only after agreeing to these Terms.

Article 1 (Eligibility and Accounts)

Starting to Use the Service: Users may begin using the Service by signing in with a Google account, by using the trial, or by any other method designated by the Operator. By beginning to use the Service through any of these methods, the User is deemed to have agreed to these Terms.
Management of Google Accounts: Users are responsible for managing the Google account they use to sign in. The Operator is not liable for any damage arising from the use of a User's Google account by a third party.
Trial Use: Trial use is subject to limits on the number of uses, the period, and other conditions.
Use by Minors: Minors who use the Service must obtain the consent of a parent or other legal guardian before doing so.
Refusal of Registration: The Operator may refuse to allow a person to begin using the Service, or may suspend an existing account, if that person has previously had their use suspended or their account deleted due to a violation of these Terms or for similar reasons.

Article 2 (Description of the Service)

The Service generates explanations of text that Users select on web pages or in PDFs using external AI services, displays those explanations near the selected text, and stores explanations and notes on the User's device so that they can be displayed again when the User revisits the page.
The Service is provided free of charge. However, Users are responsible for the devices, network environment, and data charges required to use the Service.
The Service offers the following plans. The features and usage limits available under each plan are as displayed within the Service.
- Trial Plan: A plan that can be used without signing in with a Google account. Usage is capped for each fixed period, and some features are unavailable.
- Free Plan: A plan used by signing in with a Google account. Compared with the Trial Plan, its limits are substantially higher and more features are available.
When generating explanations, the Service may use web search depending on the User's settings. Web search results may include information from third-party websites, and the Operator is not responsible for their content.
The Operator may change the content, features, and usage limits of the plans at any time.

Article 3 (License)

The Operator grants Users a non-exclusive, revocable, non-transferable, and non-sublicensable right to use the Service in accordance with these Terms. Users must not engage in any of the following acts:

Copying, modifying, redistributing, or reverse engineering the software or source code of the Service (hereinafter, the "Service Source"), or creating derivative works based on the Service Source (except to the extent permitted by law)
Accessing the Service's servers or APIs directly without going through the Service's extension, or sending large volumes of requests by automated means
Reselling or lending the Service, or transferring the right to use the Service to a third party
Using the Service to develop a competing product

Article 4 (User Content)

Ownership of Rights: All rights in the selected text, questions, notes, and other content that Users enter into the Service (hereinafter, "User Content") belong to the User or the rightful rights holder. The Operator does not acquire any rights in User Content.
Responsibility for Input: Users must confirm for themselves that sending selected text to the Service does not violate the terms of use of the relevant web page, copyrights or other third-party rights, confidentiality obligations, or the like. Do not generate explanations for text containing confidential information or other people's personal information. The Operator is not liable for any damage suffered by the User or any third party as a result of the User sending confidential information, other people's personal information, or any other information that should not be sent to the Service, except where such damage is caused by the Operator's willful misconduct or gross negligence.
Use for Processing: The Operator uses User Content solely for the purpose of generating explanations, and sends it to external AI services as set forth in the Privacy Policy. The Operator does not store User Content on its servers, and does not use it for secondary purposes or for training AI models.
AI-Generated Output: The Operator does not claim any rights in the explanations generated by the Service (hereinafter, "Generated Output"). Users may use Generated Output at their own responsibility. However, the Operator does not guarantee that Generated Output does not infringe the rights of third parties, or that it differs from Generated Output provided to other Users.

Article 5 (Nature of Generated Output)

Generated Output is produced automatically by AI and may contain errors, inaccuracies, outdated information, or content that does not fit the context of the selected text. When making important decisions, Users should verify the content against the original source or other reliable sources of information.
Generated Output is not a substitute for medical, legal, tax, financial, or other professional advice.

Article 6 (Data on the Device)

Explanations, notes, and conversation histories saved in the Service are stored only within the Chrome profile on the User's device and are not backed up to the Operator's servers.
Data on the device may be lost due to uninstallation of the extension, deletion of the Chrome profile, device failure, or other causes. The Operator has no obligation to restore, and bears no liability for, the loss of data on the device.
Data on the device is not separated by Google account, and other people using the same Chrome profile may be able to view it. Please take care when using the Service on a shared device.

Article 7 (Account Deletion)

Users may delete their account at any time by the method designated by the Operator.
When an account is deleted, the information for that account on the Operator's servers is deleted, and all explanations, notes, and conversation histories in the Chrome profile in which the deletion was performed are also deleted. This includes data saved while a different Google account was being used in the same Chrome profile. Deleted data cannot be restored.
After an account is deleted, the same Google account cannot be used to register again for a certain period.
For details on how information is handled when an account is deleted, please refer to the Privacy Policy.

Article 8 (Prohibited Conduct)

In using the Service, Users must not engage in any of the following acts:

Acts that violate, or may violate, laws and regulations or public order and morals
Acts related to criminal activity
Acts that infringe the copyrights, trademark rights, privacy rights, or other rights or interests of the Operator, other Users, or third parties
Acts intended to generate obscene, excessively violent, discriminatory, or hateful content
Acts intended to generate content that violates the usage policies of the external AI services used by the Service
Creating multiple Google accounts, repeatedly reinstalling the extension, or using any other improper means for the purpose of circumventing usage limits
Acts that place an excessive load on the Service's servers or network, or that interfere with the operation of the Service
Circumventing or disabling the Service's security features, abuse-prevention mechanisms, or authentication mechanisms
Unauthorized access or attempts at unauthorized access
Using the Service while impersonating another person
Any other acts that the Operator reasonably determines to be inappropriate

Article 9 (Suspension of Use and Changes to or Termination of the Service)

If a User violates these Terms, or if the Operator reasonably determines that a User is likely to violate them, the Operator may, without prior notice, suspend all or part of that User's use of the Service or delete the User's account.
The Operator may temporarily suspend all or part of the Service without prior notice in any of the following cases:
- When performing maintenance, inspection, or updates of the Service's systems
- When an external service used by the Service (such as AI services, cloud infrastructure, or Google account authentication) is suspended, or its specifications or terms of provision are changed
- When provision of the Service becomes difficult due to natural disasters, fire, power outages, communication failures, or other force majeure events
- Any other case in which the Operator reasonably determines that suspension is necessary
The Operator may change the content of the Service or terminate the provision of the Service. If the Operator terminates the provision of the Service, it will give advance notice a reasonable period of time beforehand.
Except as provided in Article 11, the Operator is not liable for any damage suffered by Users as a result of measures taken under this Article.

Article 10 (Disclaimer of Warranties)

The Operator does not warrant that the Service (including Generated Output) is accurate, complete, useful, fit for a particular purpose, continuously available, or free of defects or errors, or that it will function properly on all web pages and PDFs. The Service is provided "as is."

Article 11 (Limitation of Liability)

The Operator is not liable for any damage suffered by Users in connection with the Service, except where such damage is caused by the Operator's willful misconduct or gross negligence.
Notwithstanding the preceding paragraph, if the contract between the Operator and a User concerning these Terms constitutes a consumer contract as defined in the Consumer Contract Act of Japan, the Operator shall be liable for damage suffered by the User due to the Operator's non-performance of obligations or tort resulting from the Operator's ordinary negligence, but only for ordinary and direct damage actually incurred. In such case, the Operator is not liable for damage arising from special circumstances, lost profits, or damage due to loss of data.

Article 11-2 (Indemnification by Users)

If the Operator receives a claim from a third party arising from a User's violation of these Terms, the User's User Content, or the User's improper use of the Service, the User shall indemnify the Operator for any resulting damage incurred by the Operator (including reasonable attorneys' fees).

Article 12 (Changes to the Terms)

The Operator may change these Terms in any of the following cases:
- When the change conforms to the general interests of Users
- When the change does not contravene the purpose of these Terms and is reasonable in light of the necessity of the change, the appropriateness of the changed content, and other circumstances relating to the change
When the Operator changes these Terms, it will post the revised Terms on the Service's website and update the "Last Updated" date at the end of these Terms. The revised Terms take effect at the time they are posted.
If a User uses the Service after the revised Terms have been posted, the User is deemed to have agreed to the revised Terms.

Article 13 (Privacy)

The handling of User information in the Service is governed by the Privacy Policy separately established by the Operator.

Article 14 (Notices and Communications)

Notices from the Operator to Users will be given by posting on the Service's website or within the extension, or by sending an email to the email address of the User's Google account. A notice by email is deemed to have reached the User at the time it is sent.
For inquiries regarding these Terms or the Service, please contact us by email at hello@fu-sen.app.

Article 15 (Assignment of Rights and Obligations)

Users may not assign to a third party, or provide as security, their contractual position under these Terms or any rights or obligations under these Terms without the Operator's prior written consent. If the Operator transfers the business relating to the Service to a third party, the Operator may, in connection with such business transfer, transfer its contractual position under these Terms, its rights and obligations under these Terms, and User information to the transferee, and Users consent to this in advance.

Article 16 (Governing Law and Jurisdiction)

These Terms and any disputes relating to the Service are governed by the laws of Japan.
If a dispute arises between the Operator and a User concerning these Terms or the Service, the district court having jurisdiction over the Operator's place of residence shall be the exclusive agreed court of jurisdiction of first instance.

Article 17 (Miscellaneous)

Even if any provision of these Terms is held to be invalid or unenforceable, the remaining provisions shall continue in full force and effect.
The Operator's failure to exercise any right under these Terms shall not be deemed a waiver of that right.
These Terms are prepared in Japanese and English versions. For Users residing in Japan, the Japanese version prevails over the English version. For Users residing outside Japan, the English version prevails over the Japanese version. In either case, the version in the non-prevailing language is provided as a reference translation for convenience only, and in the event of any discrepancy between the two language versions, the prevailing language version as set forth above shall govern.

Established: September 27, 2026 Last Updated: September 27, 2026