Privacy Policy

Effective: October 15, 2026

koshilab ("we", "our", or "us") is committed to protecting the privacy of our users. This Privacy Policy explains how we handle information in connection with our mobile applications.

Information We Collect

Our apps are designed with privacy in mind. We do not collect or store personal information about you, and none of our apps require an account, a login, or any form of registration. Three features talk to a server in order to work — worksheet generation in 漢ドリ (Kanji Drill), book downloads in おはなし (Ohanashi), and content downloads in まるつけ (Marutsuke). All three are described in full below.

Children's Privacy (COPPA)

Our apps are suitable for users of all ages, including children, and comply with the Children's Online Privacy Protection Act (COPPA). We do not knowingly collect personal information from children under the age of 13. Our apps do not:

• Collect names, email addresses, or other personal information
• Include third-party advertising
• Include social media integration
• Allow users to communicate with other users
• Use analytics that track individual users

Data Storage

All app data — learning progress, saved worksheets, and settings — is stored locally on your device. We do not have access to it, and it is never uploaded to our servers. In まるつけ (Marutsuke), if your family is signed in to iCloud, the app’s data also syncs through your family’s own private iCloud (Apple’s CloudKit private database), which we cannot access.

Worksheet Generation in 漢ドリ (Kanji Drill)

漢ドリ (Kanji Drill) is the one exception to the sections above, and only for the worksheet generation feature. When you tap to generate a worksheet, the kanji characters you typed are sent over an encrypted connection to our server, which passes them to Anthropic's Claude API to produce example words and test sentences. Only those characters are sent — no name, email, account, device identifier, or advertising identifier is attached.

The words and sentences generated for a given kanji are cached on our server for up to 30 days, so the same character doesn't have to be generated again. The cache is keyed only by the kanji character itself and holds no information about who requested it. Tapping "Regenerate" skips the cache entirely, and its result is not stored.

To stop the service from being abused, our server briefly records the IP address that a request came from, solely to enforce a rate limit. It is used for no other purpose, is never linked to you or to what you typed, is not used for advertising or tracking, and is discarded automatically after an hour. Everything else in 漢ドリ — stroke-order animations, kanji readings, the tracing pages, and your worksheet history — works offline on your device once a kanji has been added.

Book Downloads and Subscriptions in おはなし (Ohanashi)

おはなし (Ohanashi) downloads its picture books — pictures, text and narration — from our server over an encrypted connection. A download request names only the book; nothing about you is sent with it.

To open books that need a subscription, the app also sends the signed purchase record that Apple’s App Store issues for your subscription. Our server only checks that Apple signed it, that it is for おはなし, and that the subscription is active. The record contains no name, email address or Apple Account details, and our server does not store it.

Our server runs on Cloudflare. Like any web host, Cloudflare handles the IP address a request comes from in order to deliver it; we don’t keep request logs and never use IP addresses to identify or track anyone. Reading progress, favorites and stamps stay on your device.

Handwriting, Recordings and iCloud in まるつけ (Marutsuke)

まるつけ (Marutsuke: Japanese Writing) is an iPad app for children in grades 1–3. It has no account, no login, no ads, no analytics and no tracking, and its App Store privacy label is “Data Not Collected.” Your child’s handwriting, progress, stickers and おんどく (read-aloud) recordings are stored on the iPad. If your family is signed in to iCloud, they also sync through your family’s own private iCloud (Apple’s CloudKit private database), which we cannot access. Nothing is sent to us.

The microphone is used only for おんどく, and only after your child taps the record button; iOS asks for permission first. Recordings stay on the iPad and in your family’s private iCloud.

A grown-up can share a finished page — a picture, optionally with its recording — from the parent area, which sits behind a grown-ups-only check, using the iPad’s share sheet (for example, LINE or Messages). Nothing is shared unless a grown-up chooses to share it.

The app downloads its reading passages and narration audio from our server on Cloudflare over an encrypted connection. A download request names only the content pack; nothing about you is sent with it. Subscriptions are handled by Apple through the App Store, and we receive no payment details. Using Reset in the parent area deletes the progress, stickers and recordings on the iPad and in iCloud.

Third-Party Services

Apart from the Claude API described above, which 漢ドリ (Kanji Drill) uses only to generate worksheet content, Cloudflare, which hosts the server おはなし (Ohanashi) and まるつけ (Marutsuke) download their content from, and Apple’s iCloud (CloudKit), which まるつけ uses to sync data through your family’s own private iCloud, our apps do not integrate with third-party services. We use no advertising networks and no per-user analytics. The apps are distributed through the Apple App Store and Google Play Store, each of which has its own privacy policy.

Changes to This Policy

We may update this Privacy Policy from time to time. Any changes will be posted on this page with an updated effective date.

Contact Us

If you have any questions about this Privacy Policy, please reach out through our contact form.