Privacy policy

This is an English translation of the Japanese privacy policy. If there is any difference between the two, the Japanese version prevails.

sekibun.com Administration (the "Operator") sets out this privacy policy for the handling of user information on sekibun.com (the "Site").

1. Information we collect and why

When you use the contact form, we collect your name (a nickname is fine), email address and message. We use them only to reply to you and to improve the Site, and we do not give them to third parties except as required by law.

Creating an account is optional. If you create one, we store the following on our server:

• Email address: used for signing in, confirming that the address is yours, and sending password-reset and other account messages.
• Password: stored only as a one-way hash; we never store the password itself.
• Saved worksheets: title, print code (the topic, level and number of each problem), worksheet settings (not including text typed into the name and other fields), number of problems, star, and the dates they were created and updated.
• Folders: folder names and the dates they were created.

To keep you signed in, we use a sign-in cookie (session cookie) and a verification string that protects against forged requests (CSRF token). This cookie is required for signing in and is not used for advertising or tracking. A sign-in lasts at most 30 days from the time you sign in, and you are signed out automatically after 14 days without access. We also store a small marker in your browser that tells whether you are signed in (it does not contain your email address).

To prevent unauthorized sign-in attempts and mass registrations, we keep a security log of account actions (sign-in, registration, password reset and similar) with the time, IP address and user number, and delete entries after 30 days. The log never contains email addresses or passwords. For limiting the number of attempts we use irreversibly transformed values of the IP address and email address, which are deleted within one day. Registrations whose email address is not confirmed are deleted automatically after 7 days.

Confirmation emails, password-reset links and account notices (such as a password change) are sent from a send-only address (noreply@sekibun.com) that cannot receive replies. For questions, please write to contact@sekibun.com or use the contact form.

Under "Account settings" on My page you can export your saved data as a JSON file, and you can delete your account at any time. Deleting the account immediately and permanently removes your email address, password hash, saved worksheets and folders (security log entries are removed after the period above). We use this information only to provide the account features and to prevent abuse, and we do not share it with third parties except as required by law.

Your study records (such as the number of problems solved), your worksheets and their history, drafts of online answers and your display settings (theme, clean answers and so on) are stored in your browser (local storage) and are not sent to our server unless you choose to save them to your account.

Answer files created on the answer page are saved on your device. Loading and grading answer files on the grading page happens entirely in your browser; the contents of answer files (names, answers, etc.) are never sent to our server.

2. Advertising

The Site uses Google AdSense, a third-party advertising service (this section applies from the time we start using it).

Third-party vendors, including Google, use cookies to serve ads based on your previous visits to this and other websites. Google's use of advertising cookies enables it and its partners to serve ads based on those visits.

You can opt out of personalised advertising in Google Ads Settings, or opt out of third-party vendors' cookies for personalised advertising at www.aboutads.info.

For details, see Advertising – Privacy & Terms – Google.

3. Analytics

The Site may use Google Analytics to understand how the Site is used and improve it. Google Analytics uses cookies to collect traffic data anonymously; it does not identify individuals.

You can refuse this collection by disabling cookies in your browser. See the Google Analytics Terms of Service and How Google uses information from sites or apps that use our services.

4. Information sent to third parties

For the advertising and analytics above, information may be sent from your device to the following companies.

5. Access, correction and deletion

You can view and export (download) your account data from My page at any time. Deleting your account immediately deletes your saved worksheets and other data.

If you ask us to disclose, correct or delete personal information you sent through the contact form or stored in your account, we will respond promptly after confirming your identity. Please use the contact form.

6. Disclaimer and copyright

See the Terms of use.

7. Changes to this policy

We may change this policy when necessary. The revised policy takes effect when it is posted on this page.

8. Contact

For questions about this policy, please use the contact form.

Established: October 6, 2026
sekibun.com Administration