Privacy Policy

Effective: October 16, 2026. Last updated: November 2, 2026. This is a translation of the Japanese original. If the two differ, the Japanese version prevails.

In short

Your health records, conversation history and medications are stored only on your iPhone. They are not synced with iCloud and not stored on our server.
Only when you use the AI features, the text of your conversation and a summary of your records are sent through our server to an AI provider in the United States (OpenAI). This happens only after you consent, and your name is never sent.
Our server does not store or log the content of your conversations. The AI provider does not use it to train AI models.
Apple Health data (daily totals for sleep, heart rate and steps) is shared with the AI only if you turn on that setting.
Okusuri Techo QR codes are read on your iPhone. Camera images and photos are never saved or sent, and the name, date of birth and other personal details in the code are discarded without being read.
No ads. We never sell your data. Usage analytics never include health information.
You can withdraw consent and delete all of your data at any time in the app's Settings.

1. About this policy

Rintaro Sakino ("we", "the operator") operates Koharu ("the app"). This policy explains how the app handles your information. We handle information in accordance with Japan's Act on the Protection of Personal Information (APPI) and other applicable laws. If you live outside Japan, you may also have rights under the laws of your country; contact us to exercise them.

The app has no account registration. We never receive your name, email address or phone number through the app.

2. Data kept only on your iPhone

The following data is stored only in the app's own storage on your iPhone. It is not synced with iCloud and not stored on our server. We cannot see it.

Your answers during setup (what Koharu calls you, the conditions you live with, the medications you take, where to check air pressure, the check-in time, your first entry and how you heard about Koharu). If you answered them in an earlier version of the app, this also includes your goals, symptoms, age range, sex, how you handle bad days, usual energy, number of people you can rely on, the hardest thing for you, answers to the questions about your symptoms and health, and mood.
Your conversation history with Koharu
Your health log (symptoms and severity, energy, mood, triggers, period, notes)
When each symptom occurred (morning, afternoon or night) and how it feels (such as "throbbing")
Your medications and dose records (taken, skipped, and so on), including the names, doses, directions and dispensing dates of medications added from an Okusuri Techo QR code
What Koharu remembers
Daily totals read from Apple Health, and air pressure history
Settings such as reminder times and the prefecture you chose

The appointment report (PDF) is created on your iPhone. You decide whether to share it and with whom.

If you back up your whole iPhone (iCloud Backup or a backup to a computer), this data is included in that backup. Deleting the app deletes this data from your iPhone. However, the anonymous user ID, usage counts and subscription status on our server remain (see section 4). If you reinstall the app, it starts with a new anonymous user ID that is not linked to the old records (your subscription is linked to the new ID when the app sends your purchase information again). To remove them as well, use Settings → Delete all data before deleting the app (see section 15).

3. What the AI features send, and to whom

When data is sent

Data is sent only when you use one of the three features below, and only after you consent on the "How your data is handled" screen during setup (or in Settings → AI). If you do not consent, you can still use manual logging, medications, charts and air pressure.

Talking with Koharu (text or voice)
The "first entry" step during setup (extracting a log from one sentence about your day)
Writing the text of the appointment report

What is sent

Data	Contents	When
Conversation text	What you typed or said, and Koharu's replies in the same conversation. Your voice is turned into text on your iPhone before anything is sent.	When you use an AI feature
Summary of your records	Today's date and language; the conditions you live with, the names of your medications and of symptoms you logged recently; only if you answered them in an earlier version of the app, your goals, symptoms, age range, sex, how you handle bad days, usual energy, number of people you can rely on, the hardest thing and answers to the questions about your symptoms and health; what Koharu remembers; recent daily records (severity, energy, mood, symptoms, triggers, medications); text of patterns found	When you use an AI feature
Report figures	Numbers calculated on your iPhone for the chosen period (such as how often a symptom was logged and its average severity)	When you create an appointment report
Sleep, heart, steps and air pressure	Daily hours of sleep, resting heart rate, heart rate variability, steps, and the 24-hour change in air pressure	Only while Settings → AI → "Share sleep and heart data with AI" is on

Never sent: what Koharu calls you (the AI writes a placeholder, and your iPhone inserts the name), audio, location, individual Apple Health samples, and email addresses or phone numbers (we do not collect them).

Recipients

The data goes through our server (Google Cloud by Google LLC, Tokyo region) to the AI provider below. Our server only relays the data to produce a reply; it does not store or log the content of your conversations.

Recipient	Country	Use	Retention by the provider
OpenAI	United States	To write replies, extract logs and write report text, and to monitor misuse. Not used to train AI models.	Kept for up to 30 days for abuse monitoring, then deleted. It may be kept longer if required by law or reasonably necessary to protect OpenAI's services.

Provider documentation: OpenAI API data controls

Consent for sensitive information and transfer to a third party in a foreign country

Your conditions, symptoms, medications and health records may be "special care-required personal information" under the APPI. We ask for your consent in advance before receiving this information and providing it to the AI provider in the United States (APPI Article 20(2) and Article 28(1)). The consent screen shows what is sent, the recipient company and its country, and how long it keeps the data.

The personal information protection system of the United States

According to a survey by Japan's Personal Information Protection Commission (PPC) (information as of October 2021):

The United States has no comprehensive federal law on personal information protection. Sector-specific laws include the Electronic Communications Privacy Act (ECPA), the Gramm-Leach-Bliley Act (GLBA) for financial institutions, and the Health Insurance Portability and Accountability Act (HIPAA) for health information.
California, where OpenAI is headquartered, has a comprehensive law, the California Consumer Privacy Act (CCPA).
The United States has participated in the APEC Cross-Border Privacy Rules (CBPR) System since July 25, 2012.

For details, see the PPC's survey of personal information protection systems in foreign countries (United States (federal), California; in Japanese).

Measures taken by the recipient

OpenAI's terms state that content received through the API is used only as needed to provide the service and to monitor misuse, and is not used to train AI models.
Content is deleted after the periods in the table above.
OpenAI protects data with encryption in transit and at rest and access controls, and is audited by third parties for information security (such as SOC 2 Type II) (OpenAI Trust Portal).

4. Data stored on our server

We do not store health information on our server. We store only the following.

Data	Contents	Use
Anonymous user ID	A random ID created by Firebase Authentication's anonymous sign-in, with its creation time and last sign-in time	To link usage counts and subscription status
Usage counts	For each day (Japan time): how many times you talked with Koharu, used the "first entry" step and created a report, and whether you have used the first conversation	To apply the free limit and the limits that prevent abuse
Subscription status	Apple's transaction number (original transaction ID), product, purchase date, expiry date, billing grace period, refund or revocation date, and whether it is a production or test purchase	To decide whether Premium is available
Request logs	Time, IP address, app and OS type, and result of each request to our server. No conversation content.	To investigate problems and prevent abuse

For every request, Firebase App Check and Apple's App Attest confirm that it comes from a genuine, unmodified copy of the app. This check does not involve the content of your records or conversations.

Our server and database run on Google Cloud by Google LLC (Cloud Functions for Firebase and Cloud Firestore) in the Tokyo region. Anonymous sign-in (Firebase Authentication) runs in Google's data centers in the United States.

5. Usage analytics (Google Analytics for Firebase)

To learn, for example, where people get stuck in the app and make it easier to use, we use Google Analytics for Firebase by Google LLC. It receives:

Screens and actions: how far you got in setup, how many conditions and medications you chose during setup (not their names), the option you chose for how you heard about Koharu, whether you chose your current location or a prefecture for air pressure (not which prefecture), whether permission for notifications or Apple Health was requested, views of the purchase screen and purchase results, views of the offer shown to people who turned off auto-renew and the reason they chose there (from a list) and the result, and how many times you talked with Koharu and whether by text or voice
App launches, time in the app, and purchases (product and price)
Device model, OS and app version, and country or region (estimated from the IP address)
An ID that Google Analytics creates for each app installation (app instance ID)

It never receives: what Koharu calls you; names of conditions, symptoms or medications; health or mood values; conversation or free text; Apple Health data; location; or the advertising identifier (IDFA). The app keeps an allow-list of what may be sent so that nothing else is sent.

Analytics is not used for advertising or tracking (the app does not ask for App Tracking Transparency permission). Google signals and ads personalization are turned off. Under our Google Analytics settings, event-level data is deleted after 2 months and user-level data after 14 months.

For how Google handles data, see the Google Privacy Policy and How Google uses information from sites or apps that use our services.

6. Air pressure and location

To show changes in air pressure and compare them with your log, the app gets air pressure from Apple's WeatherKit. Location is used only "While Using the App" and only as an approximate location. If you do not allow location, the app uses the location of the capital of the prefecture you choose.

Your location is sent only to Apple to get the air pressure; it is never sent to our server. See Apple's Privacy Policy. Air pressure data is stored on your iPhone.

7. Apple Health (HealthKit)

Only if you allow it, the app reads these four types from Apple Health. It never writes to Apple Health.

Sleep
Resting heart rate
Heart rate variability (SDNN)
Steps

The values are added up per day on your iPhone, stored there, and used for charts next to your log, patterns and the appointment report. Only these daily totals are shared with the AI, and only while Settings → AI → "Share sleep and heart data with AI" is on (see section 3).

Apple Health data is never used for advertising, marketing, sale of data or usage analytics, and is never synced to iCloud (it is included in your iPhone's own backup; see section 2). You can change access at any time in iPhone Settings → Privacy & Security → Health → Koharu.

8. Voice input

To talk to Koharu by voice, the app asks for microphone and speech recognition access. Your voice is turned into text on your iPhone. The audio is never stored or sent anywhere. The resulting text is treated as conversation text (see section 3).

9. Reading Okusuri Techo QR codes (camera and photos)

You can add prescribed medications by reading the QR code (in the electronic medication handbook format) that Japanese pharmacies print on the receipt and the medication handbook (Okusuri Techo) sticker. To read it with the camera, the app asks for camera access. To read it from a photo, the app reads only the photos you choose (it does not ask for access to your photo library).

Camera images and photos are used only to read the QR code on your iPhone. They are never saved or sent.
The name, date of birth, sex, address, clinic, doctor and other personal details in the code are discarded without being read. Only the names, doses, directions and dispensing date of the medications you confirm are saved on your iPhone as medication records.
Reading a QR code sends nothing to our server or to the AI provider. Medications you add this way are handled like your other medication records: if you have consented to the AI features, they may be included in the summary of your records (see section 3).

10. Notifications

Daily check-ins, medication reminders and the reminder 2 days before a free trial ends are all scheduled on your iPhone. We do not use a push notification server and never receive a notification identifier.

11. Purchases

Apple processes subscription payments. We never receive your name, payment method or Apple Account details.

To confirm whether Premium is available, our server checks the transaction information signed by Apple (transaction number, product and period). Renewals, refunds and revocations are reflected through notifications Apple sends to our server (App Store Server Notifications).

What you declare when choosing the Support plan (for example, being on leave or a student) is never stored or sent.

12. Purposes of use

We use the information we receive only to:

Provide the app's features (Koharu's replies, extracting logs from conversations, and the text of appointment reports)
Manage free usage limits and subscription status
Prevent fraud and abuse
Respond to inquiries
Investigate problems and analyze how to make the app easier to use

We never use it for advertising, sale of data or marketing based on health information.

Except for providing data to the AI provider in section 3 (based on your consent) and where required by law, we do not provide your information to third parties.

The app uses these services:

Google LLC: Firebase (Authentication, App Check, Cloud Firestore, Cloud Functions, Hosting) and Google Analytics for Firebase
Apple Inc.: WeatherKit (air pressure), App Store payments, HealthKit (read on your iPhone only)
OpenAI: writing AI replies (see section 3)

14. Retention

Data	Retention
Records on your iPhone	Until you delete them (including by deleting the app)
Content sent to the AI provider	As in the table in section 3 (generally deleted within 30 days)
Conversation content on our server	Not stored
Anonymous user ID and subscription status	Until you use "Delete all data". After deletion, it is also removed from Google's backups within 180 days.
Usage counts	Deleted automatically 90 days after the day they record
Request logs	Deleted automatically after 30 days (IP addresses logged by anonymous sign-in: a few weeks)
Usage analytics	Event-level data 2 months; user-level data 14 months
Emails to us	As long as needed to respond

15. Withdrawing consent and deleting data

Stop sending data to the AI: Turn off Settings → AI → "Use AI". Nothing is sent after that. Content already sent is deleted when the provider's retention period ends. If you turn it on again, the consent screen is shown again.
Stop sharing sleep and heart data with the AI: Turn off Settings → AI → "Share sleep and heart data with AI".
Edit or delete what Koharu remembers: In Settings → "What Koharu remembers", you can view, edit and delete each item.
Delete all data: Settings → "Delete all data" deletes all records on your iPhone and, on our server, your anonymous user ID, usage counts and the link to your subscription. Deleted data cannot be recovered. If you are offline, the records on your iPhone are deleted right away and the server records are deleted automatically the next time Koharu can connect.
Change permissions: You can change access to Apple Health, location, microphone, speech recognition, camera and notifications at any time in iPhone Settings.

"Delete all data" does not cancel your subscription. Cancel it in the App Store (how to cancel). Data stored in Apple Health itself also stays in Apple Health.

If you delete the app first, we have no way to tell which server records belong to you. To delete the server records too, use "Delete all data" before deleting the app.

16. Your rights and requests

You can ask us, by email (section 21), to notify you of the purposes of use, or to disclose, correct, add to, delete, stop using, erase, or stop providing to third parties your personal information, or to disclose records of provision to third parties, as provided by the APPI. There is no fee.

Because we do not hold names or email addresses, we may ask questions such as when you started your subscription to find the relevant data. If we cannot identify it, we may be unable to fulfil the request. You can view, edit and delete the data on your iPhone within the app.

17. Security measures

Policy and rules: We have set this policy and decided how information is collected, used, stored and deleted.
Organization: The operator is responsible for handling information. If a data breach occurs, we report it to the Personal Information Protection Commission and notify you as required by law.
People: No one other than the operator handles the information.
Physical: Devices used for administration are protected with screen locks and disk encryption.
Technical: All communication is encrypted. Our server accepts requests only from the genuine app that passes App Check and sign-in verification. The database cannot be read or written directly from users' devices. AI provider keys are managed in Google Cloud Secret Manager. Conversation content is never written to logs.
Understanding foreign environments: Our server and database are in Japan (Tokyo). Anonymous sign-in and usage analytics (Google LLC) and the AI provider (OpenAI) handle information in the United States. We take the measures above with an understanding of the US system (see section 3).

18. Age

The app is for people aged 18 and over. People under 18 may not use it.

19. This website

This website (koharu.process-craft-ai.com) uses no analytics tools and no cookies. It is served by Firebase Hosting by Google LLC, which may keep delivery logs (such as IP addresses).

20. Changes to this policy

If we change this policy, we will post the new version and its date on this page. If we start sending more information to the AI, or change or add AI providers, we will ask for your consent again in the app.

21. Contact

For questions, requests or complaints about this policy or how we handle information, email:

rintaro.sakino@process-craft-ai.com

Operator: Rintaro Sakino (responsible for handling personal information). We will provide our address without delay upon request.