Privacy Policy

Last updated May 30, 2026 · Operator: Jason Ye (叶宇和), Tokyo, Japan · yyyyy.yeyuhe@gmail.com

In short: Tetsuzukit runs locally on your Mac. We do not collect, transmit, sell, or analyse your data. No accounts, no telemetry, no analytics, no servers. Your profile data lives on your Mac — we never see it.

1. What data Tetsuzukit handles

When you create a profile, Tetsuzukit may store the following on your Mac only:

Stored as JSON in the folder you chose

Your name in kanji, katakana, hiragana, and romaji
Your address in Japanese and romaji formats
Your phone number(s), date of birth, and nationality
An emergency-contact name / phone, if you provide one
The last 4 digits of your My Number, if you choose to enter it (the full 12-digit number is never stored)
App metadata (timestamps, profile labels)

Stored in the macOS Keychain (encrypted by your system)

Your residence card (在留カード) number, bank account details, and passport number

Never stored

Your full 12-digit My Number; your Apple ID, Touch ID, or login password; anything you didn't type into Tetsuzukit

2. Where the data lives

You choose the location during first-run setup:

Application Support (default): ~/Library/Application Support/Tetsuzukit/
A folder you choose: a Tetsuzukit/ subfolder inside it. If you place it in iCloud Drive, Apple's sync may copy it to your other devices — that is your choice; Tetsuzukit does not control it.

Profile files are plain JSON you can open, back up, or delete with any tool.

3. Network behaviour

The Mac App Store version of Tetsuzukit makes zero app-initiated outbound network requests. We have no servers that store your data, no analytics, no crash-reporting, and no third-party tracking SDKs. (macOS itself may perform standard system checks such as receipt validation; those are Apple's and contain no Tetsuzukit profile data.)

4. Payments

Tetsuzukit is distributed through the Mac App Store. Purchases (the optional Pro upgrade) are handled entirely by Apple via StoreKit; Apple does not share your payment details with the app, which simply checks whether a valid entitlement exists. See Apple's Privacy Policy.

5. Children

Tetsuzukit is not directed to children under 13. We collect no data about anyone, so there is nothing to collect for any age group.

6. International users & your rights

Tetsuzukit does not transmit your data, so there are no cross-border data flows. Under GDPR, UK GDPR, PIPL, APPI, CCPA, and similar laws: your data stays on your machine. To erase it, use Settings → Privacy → Delete Tetsuzukit profile data, which wipes every JSON file and Keychain entry the app wrote. We hold no copy to delete because we never had one.

7. Changes

We update this Policy when the app changes, not for marketing reasons. The current version always lives at https://jasonyeyuhe.github.io/tetsuzukit/privacy/; material changes are noted in the app's release notes.

8. Contact

Privacy questions: yyyyy.yeyuhe@gmail.com.