Policy version: 2026-10-16-1. Applies from publication of this version.
Publisher: WENYU SUN, Tokyo, Japan.
Privacy and support contact: ewanesun@gmail.com.
What this policy covers
TETSU is an iPhone focus tool. With your permission, it uses Apple's Screen Time frameworks to restrict the apps, categories and websites you select during focus sessions and scheduled periods. This policy distinguishes data kept by the app on your iPhone from information you choose to send to support and connection data processed when you visit our website.
Information kept on your device
TETSU stores selected Screen Time tokens, session and schedule rules, early-exit requests, setup completion, the latest scheduling callback and its time, and your terms acceptance record (version, text digest, time and language). A text digest is a fingerprint of the terms you accepted. These records are kept in local storage shared between TETSU and its Screen Time extensions so they can apply your rules and show their state. The current permission status is read from iOS.
The app does not send these records or your selections to the publisher. It has no TETSU account, developer backend, advertising, tracking or analytics SDK, or cloud sync. It does not request access to your contacts, location, photos, microphone or health information. Apple's selection interface supplies tokens for the items you choose; TETSU does not turn them into browsing or app-usage histories.
Your choices and deletion
You can change TETSU's Screen Time permission in iOS Settings. Revoking permission affects enforcement but does not itself delete saved settings. Reset TETSU data deletes the app's local settings and records when no rule lock remains; an original schedule window can keep reset unavailable after an early exit.
App removal, backups and restoration follow iOS behavior and your settings. A device backup may retain data. TETSU provides no separate cloud backup, and the publisher cannot remotely inspect, restore or delete these local records. Deleting TETSU does not delete email you previously sent to support.
Optional support correspondence
If you email support, the publisher receives your address, message and any screenshots or diagnostic files you choose to attach. We use this information to answer your request, investigate the issue, maintain security and meet applicable legal obligations. Do not send passwords, verification codes or unnecessary sensitive information, including private app selections.
The support mailbox uses Google Gmail. Google processes email through its infrastructure, which may include servers outside your country. Its own service and data-handling practices are described in Google's Privacy Policy.
We retain support correspondence only while needed for the request, related troubleshooting, security or applicable legal obligations. When those purposes no longer require identifiable correspondence, we delete it or remove identifying details. There is no fixed automatic deletion period. Provider backups and deletion processes may retain copies for a further period; deletion from the mailbox does not guarantee immediate removal from every provider backup. You can request deletion through the privacy contact above.
Website infrastructure
The support, privacy and terms pages are static pages hosted on Cloudflare Pages. We have not added advertising or analytics scripts or configured Cloudflare Web Analytics. The pages themselves do not set tracking cookies.
Cloudflare may process IP addresses, request and connection information, and security data to deliver and protect the site. Its processing, international transfers and infrastructure retention are described in Cloudflare's Privacy Policy. We do not promise that the hosting infrastructure keeps no logs or that its records are deleted immediately. This website processing is separate from the app's device-local focus records.
Requests and questions
Email the privacy contact to ask about information you sent us or to request access, correction, deletion, a restriction on use or another right available under applicable law. Describe the request and the relevant correspondence. We may need proportionate information to verify that the request concerns you; never send a password or verification code. We respond in accordance with applicable law and explain any lawful reason that prevents us from fulfilling a request. This contact also accepts privacy complaints. Your rights to contact a competent privacy authority remain available.
Requests to the publisher concern information the publisher holds. Apple, Google and Cloudflare also have their own privacy contacts and processes for information they control. The publisher cannot access your iPhone's local records remotely.
Apple services, terms and changes
Apple manages Screen Time authorization, App Store purchases, device backups and system diagnostics under its own practices and your settings. The Terms of Use and Risk Notice describes TETSU's restrictions and delayed early exit. Accepting the terms does not authorize undisclosed data collection or replace Apple's Screen Time permission.
We will update this policy when our practices change and identify the revised version and when it applies. Practical help is available on the Support page.