Privacy Policy

This Privacy Policy is provided in Japanese and English. If the two versions differ, the Japanese version prevails.

This page explains what information this site collects and how it is used. If you want a plain overview of what is and is not saved, see the How your data is handled page.

Information we collect

We collect the email address used for registration and sign-in, and the records of its authentication. If you purchase paid content, we save the records of the purchase and the subscription state. Credit card details are processed by Stripe, the payment processor, and this site neither collects nor stores them.

In addition, we save the articles you liked, the articles a subscriber added to favorites, the body and display name of comments a subscriber posted on articles, and the daily usage counts we keep to manage the cost of Matsumotory-kun and search. The favorites of logged-out and free accounts, the on/off state of Matsumotory-kun's hints, your conversation history with Matsumotory-kun, and which articles you have read and where you left off, remain only in this device's browser rather than in your account. The conversation history is a device-local memory for looking back and continuing where you left off, and you can delete it at any time from the chat screen.

Sign-in links, and notices about single purchases and cancellation reservations, are sent through an email delivery service. Records of the sending remain on the delivery platform.

Likes, favorites, and Matsumotory-kun's hints

Likes and favorites are used only to build your shelf, to serve as hints for Matsumotory-kun's answers, and to tally totals per article. We do not use one reader's reactions in output to another reader; there is no cross-reader use. Matsumotory-kun's hints use only the titles of articles, and you can turn them off with the toggle next to Matsumotory-kun's input box. When turned off, likes and favorites are not sent to the hints.

Dialogue with Matsumotory-kun, and search

The content of Premium members' dialogue with Matsumotory-kun is not saved on this site. What we save is only the daily usage count used to manage cost. The content of the dialogue is sent to Google's generative AI on the spot to generate an answer, but it is not kept as a record on this site's side.

Question text you enter in archive search is not saved on this site either. The question text is sent to Google's generative AI on the spot for the processing that measures semantic closeness. The processing is momentary, and what we keep is only the daily count of searches.

Analytics and cookies

We do not use cookies for advertising or tracking. If we introduce analytics, we will choose a method that does not use cookies, and add a note to this page when we do. We use only the cookies necessary to keep you signed in.

This site has no mechanism to send information from users' devices to external advertising or analytics providers. Sending information to keep the sign-in and purchase state is used only to provide this site's service, and is not sent to any external third party.

Purpose of use

The information we collect is used to provide sign-in, to provide purchased content, to manage the subscription state, and to respond to inquiries. It is not used for any other purpose.

Provision to third parties and outsourcing

Except where required by law, we do not provide the information we collect to third parties. To operate the site, we outsource authentication and data storage to Supabase, payments to Stripe, email delivery to Resend, and content delivery to Cloudflare. The generation processing for Matsumotory-kun's answers and archive search is outsourced to Google's generative AI. The dialogue and question text are sent to Google on the spot for generation and processed in the United States. They are not stored on this site's side, and we use an API under terms where Google does not use this content to train its models. If you sign in with a Google account, account information such as your email address is exchanged with Google for the authentication link. The same applies if you sign in with a GitHub account: account information is exchanged with GitHub for the authentication link. Google and GitHub are both United States providers, and the account information involved in the authentication link is processed in the United States.

The content sent through the contact form and the email address written for a reply are received and stored in the United States by Google, which provides the form mechanism, and the operator reads them to respond. They are not stored in this site's own database. Those that have been handled are deleted.

Some of these outsourcing providers place their servers outside Japan. Along with the outsourcing, the information we collect may be stored or processed in the following countries. Supabase, the provider for authentication and data storage, stores it in Japan. Stripe, the provider for payments, Resend, the provider for email delivery, and Google, the provider for answer and search generation, process it in the United States. Cloudflare, the provider for content delivery, chooses the most suitable location each time from a delivery network distributed around the world, so which country's location processes it is not fixed in advance and cannot be specified by country name. In practice, locations in many countries, including Japan, are used.

When we entrust the handling of personal data to a provider located in a foreign country, we do so after confirming that the provider has a system in place to protect personal data. If you need information about a provider's level of personal data protection, please request it through thecontact form.

The business that handles personal information

The business that handles this site's personal information is Ryosuke Matsumoto, running it as an individual under the name matsumotory. The address is disclosed without delay upon request. Please request it through the contact form.

Measures for secure management

The information we collect is stored in an environment managed by the provider we outsource authentication and data storage to, with communication encrypted. Access to the data is limited to you and the operator. Authentication is done by confirming an email address, and we hold no password.

Retention and deletion

You can delete your account yourself from the account page. When you delete it, your likes and favorites, comments and display name, and question records are erased. Payment records that we are required by law to retain remain. If you cannot do this yourself, you can also let us know through the contact form.

Requests for disclosure, correction, or deletion

When you request the disclosure, correction, suspension of use, or deletion of your own information, please let us know through the contact form. After confirming that you are the person concerned, we will respond in accordance with the law. There is no fee. Payment records that we are required by law to retain are kept within the scope of that obligation.

Where to raise complaints

Complaints and inquiries about the handling of personal information are received through thecontact form.

Enacted on 2026-07-07. When the content is revised, we update the text on this page and announce it.