Tsugikan Privacy Policy

This policy explains how K-Cubed Lab ("we") handles information in the smartphone app "Tsugikan" (the "App"). If there is any difference between this English version and the Japanese version, the Japanese version prevails.

Effective / last updated: 2026-10-29

Our approach

• The app does not ask for information that directly identifies you, such as your name, email address or phone number. There are no user accounts.
• As far as possible, information is processed and stored only on your device.
• We do not sell your information.

Your bookshelf

Information about the books you register (title, author, cover image URL, etc.) is stored on your device and is not sent to our servers. Deleting the app deletes this information.

Camera and photos

• The camera is used to scan book barcodes. The camera image is processed on your device and is neither saved nor sent.
• If you take a photo of a book cover, the photo is stored only on your device.

Backup and export

Backups and CSV exports are written only to the location you choose. They are never sent to us.

Calendar

When you add a release date to your calendar, the app only passes a draft event to your device's calendar app. The app does not read your calendar.

Book search and cover images

To look up books, the search terms or ISBNs you enter are sent to the services below. Only what is needed for the search is sent, and it does not include information that identifies you. As with any network request, these services receive your IP address and similar connection information.

• Rakuten Web Service (Rakuten Group, Inc.), via a relay server we operate on Cloudflare. The relay uses your IP address temporarily for rate limiting but does not record it, and does not store search results.
• NDL Search (National Diet Library, Japan), which queries the National Diet Library's collection and the Media Arts Database (manga).
• openBD (Calil Inc. and Hanmoto.com)
• Google Books API (Google LLC)
• Open Library (Internet Archive)

Cover images are downloaded from Rakuten, Google and Open Library. For Open Library, the image URL contains the ISBN.

Purchase links

The app contains Rakuten affiliate links. Tapping one opens Rakuten's website, where Rakuten Group, Inc.'s privacy policy applies.

Advertising and analytics

The app does not include any advertising or analytics tools.

Sharing with third parties

Except for the transmissions described on this page, we do not share your information with third parties unless required by law.

Children

The app is not primarily directed at children under 13.

Changes

We may update this policy as needed. We will announce significant changes on this page or in the app.

Contact

K-Cubed Lab
Address: To be announced
Email: contact@kcubedlab.com