Privacy Policy

Last revised: September 10, 2026

The symptom-tracking app "Seren" (the "Service") is an app for recording and reviewing chronic pain and other symptoms. Daiki Yamaguchi, the provider of the Service ("we," "us," or "our"), regards the protection of your personal information as important, complies with the Act on the Protection of Personal Information of Japan (the "APPI") and other applicable laws, and establishes this Privacy Policy (this "Policy").

Before you begin, here are three things we especially want you to know (see the referenced sections for details):

• Your health and symptom records are collected only with your consent, as special care-required personal information (a category of personal information given heightened protection under Japanese law; comparable to "consumer health data" or sensitive data under U.S. state laws).
• We do not use your records for advertising and do not sell them to third parties. We also do not share them with third parties without your consent.
• You can delete your account and your records at any time from the app's settings screen.

For residents of the United States, we also publish a separate Consumer Health Data Privacy Policy (available on the Service's legal documents page, and from the app's settings screen when the app is displayed in English), which describes our handling of consumer health data under U.S. state laws such as the Washington My Health My Data Act.

1. Service Provider and Contact

• Provider: Daiki Yamaguchi (an individual)
• Contact: support.seren@gmail.com
• Our postal address and telephone number will be disclosed without delay upon request. If you would like them disclosed, please contact us at the address above.

2. Information We Collect

The Service collects the following information.

Special care-required personal information (health data)

The following information you record constitutes special care-required personal information under the APPI. We collect it only with your consent.

• Health records (information about your health that you record in the app, such as pain locations and intensity, sleep, mood and psychological state, exercise, medications, bowel movements, menstruation, and free-text notes)
• Conversations with the AI (including free-text descriptions of your symptoms)
• AI memory (information organized from your conversations and records about your circumstances, what matters to you, usual patterns in your records, and temporary circumstances, together with their evidence periods. It may include health or symptom information. We also store the content and supporting information before and after corrections and deletions, a history of those actions, and known context such as excerpts from your chat input so later generation can take them into account. You can turn this off in settings)
• In-app feedback (free-text comments and requests. They may include descriptions of your health or symptoms)

Other information

• Authentication information (your email address, or identifiers associated with your Google or Apple account; when your name is provided by your Google or Apple account, it is included)
• Usage logs, device identifiers (including a push notification delivery token when you allow notifications on your device), and technical information about the app's operation
• Crash and defect diagnostic information (stack traces, device model, OS version, and the like). Collected only with your separate, optional opt-in consent; it does not include health data such as your symptoms.
• App usage data (app launches and usage counts, device model, OS version, and the like). Collected only with your separate, optional opt-in consent; it does not include health data such as your symptoms. Due to the analytics tool's design, coarse country/region-level information derived from the sending IP address may accompany this data (unlike "location information" below, this does not measure your device's location).
• App settings (your preferences, such as AI task permissions)
• Purchase status of the paid plan (subscription) — purchase, renewal, and cancellation history, and the subscription expiration date. Payment information such as credit card numbers is handled by Apple; we do not collect it.
• Approximate location (latitude/longitude rounded to a coarse area of about 11km, used to retrieve the weather and barometric pressure for your area). Collected only if you grant the OS location permission. All other features remain fully available if you do not grant it.

3. Purposes of Use

We use the collected information for the following purposes.

• Providing features for saving, displaying, and reviewing your symptom and other records
• Showing the weather and barometric pressure for your area, and relating weather and pressure to your records (AI chat responses, Insights, and when you review your records) (only if you grant the location permission)
• Providing AI features that organize your records and converse with you
• Remembering information about you to support responses across conversations and summaries that identify differences from your usual records and events that matter to you (AI memory; turning it off stops new automatic storage and use in both chat and summaries. You can still view, edit, and delete saved entries in settings while it is off)
• Providing features that let you select and copy your records or AI responses to share them with third parties such as your healthcare providers
• Confirming the purchase status of the paid plan (subscription) and reflecting it for the purchasing user (including checking purchase status when determining AI usage limits)
• Managing the volume of AI feature usage and preventing abuse and excessive load
• Delivering push notifications to let you know when AI has a question about your review, or when its analysis has completed or failed (only if you allow notifications on your device; notifications never contain your symptom records or AI-generated text)
• Maintaining and improving the Service and addressing defects
• Responding to your inquiries

We do not use the information beyond the scope necessary to achieve the above purposes. We do not use the collected information for advertising delivery or optimization.

4. Provision to Third Parties

1. We do not provide personal information, including special care-required personal information, to third parties except with your consent or where permitted by law. Provision based on your consent (including cases where you choose to share your records with healthcare providers or other parties) is not restricted by this Policy.
2. We do not provide or sell your records to third parties for advertising or marketing purposes. We do not sell them to data brokers.
3. If a court, the police, or another public authority makes a legally binding disclosure demand, we comply only to the extent of our legal obligations. We operate the Service under the laws of Japan, and we respond to disclosure demands from foreign authorities in accordance with Japanese law and applicable international frameworks.

5. Service Providers and Transmission of Information (Including Third Parties Located Outside Japan)

We entrust the handling of personal data to the following providers to the extent necessary to provide the Service. As you use the Service, the app transmits information to these providers. Under the APPI, providers that process personal data on our behalf in this way ("entrusted" processing) are treated differently from the third-party provision addressed in Section 4, and we remain responsible for supervising them (Section 9). Some are located outside Japan; as required by the APPI, we provide information below about the destination country, its data-protection regime, and the measures taken by each recipient.

The United States does not have a comprehensive federal law equivalent to the APPI, but each provider below handles data within the scope of its purpose and takes security measures, under our contractual terms and its published privacy policy. For information about data-protection regimes in other countries, see also the survey published by the Personal Information Protection Commission of Japan.

• Google LLC (Firebase: authentication, database, server processing, push notifications) — U.S. company (record data stored in Japan)
  • Information transmitted: authentication information (including your name when provided by your Google or Apple account), record data including symptoms, technical information about the app's operation, approximate location (for retrieving weather/pressure data; only if you grant the location permission), a push notification delivery token (only if you allow notifications on the device)
  • Purpose: authentication, storage of record data, server processing, retrieving the weather/pressure data for your area, delivering push notifications (to let you know when AI has a question about your review, or when its analysis has completed or failed; notifications never contain your symptom records or AI-generated text)
  • Measures: record data is stored in Japan (Tokyo region, asia-northeast1). Encryption in transit and at rest and access controls apply. Location is used only for the retrieval processing; only the value rounded to a coarse area (about 11km) is stored in Firestore. The retrieved weather/pressure data is stored as area-level values shared among users in the same area, and, for reference when generating AI chat responses and for relating it to your records in Insights and when you review your records, the weather and pressure for each day (weather code and daily minimum pressure) is also stored linked to your account. This per-user copy contains no location or area and is deleted when your account is deleted. Separately, to prevent abuse we temporarily keep a short history (up to 20 entries) of the rounded areas you have recently accessed, linked to your account; this is deleted when your account is deleted
• Google LLC (Firebase Crashlytics: crash diagnostics) — United States
  • Information transmitted: crash and defect diagnostic information (stack traces, device model, OS version, and the like)
  • Purpose: detecting and fixing app crashes and defects
  • Measures and notes: transmitted only with your separate, optional opt-in consent, which you can change or withdraw at any time from the app's settings screen. When you withdraw, further transmission stops and unsent diagnostic reports remaining on your device are discarded; diagnostic information already transmitted before withdrawal remains within the tool until its retention period expires (see Section 7). The diagnostic information transmitted does not include health data such as your symptoms
• Google LLC (Firebase Analytics: usage analytics) — United States
  • Information transmitted: app launches and usage, device model, OS version, and the like
  • Purpose: analyzing how the app is used, to improve the app
  • Measures and notes: transmitted only with your separate, optional opt-in consent, which you can change or withdraw at any time from the app's settings screen. When you withdraw, further transmission stops and the analytics identifier on your device (the App Instance ID) is reset. The usage data transmitted does not include health data such as your symptoms. Ad personalization features are disabled. After withdrawal or account deletion, usage data already transmitted remains within the analytics tool for its retention period (see Section 7)
• OpenAI, L.L.C. (AI analysis service) — United States
  • Information transmitted: your input to the AI chat (which may include descriptions of your symptoms), the records and AI memory the AI references, the weather and air pressure of roughly the last 7 days, the immediately preceding exchange used for the safety check on the AI's response (see Section 9), for the Insights feature, a daily summary of roughly the last 90 days of your records (pain level, sleep hours, and whether activity, medication, or menstruation was recorded) together with the weather and air pressure for the days in that period on which weather was retrieved, and, when you create a summary with the Summary feature and when you answer additional questions on its screen, the daily numerical records in the chosen period (pain level, sleep hours, and whether activity, medication, or menstruation was recorded) and weather and air pressure, the worded parts of your records (note text, medication names, activity descriptions, and pain locations and types), the period's statistics, anything you entered as something to check at your appointment, the context, questions, and options for additional questions (including unanswered questions), and your additional-question answers
  • Purpose: generating AI responses that organize your records and converse with you, safety checks on the AI's response and on AI memory candidates generated from records and their source context (part of the multi-layer check that prevents the AI from giving medical advice), generating Insights that look for tendencies in your records and describe them in words (performed automatically on a schedule, without any action on your part), and exploring and describing tendencies from the numerical records and weather/pressure in a summary's chosen period, as well as describing a summary's events and suggesting things to tell your doctor (performed when you create a summary and when you answer additional questions on its screen; additional-question context, questions, and options may be sent again for translation, while questions and answers may be sent again for follow-up questions and final generation. Unanswered question text is used to avoid repeating questions). The numerical-record and weather/pressure processing does not include chat text, free-text notes, AI memory, or profile information.
  • When AI memory is enabled: chat and summary generation also receive saved memories (what you have told us, patterns from your records, temporary circumstances, and evidence periods) and recent correction and deletion history. This helps identify differences from your usual records and events that matter to you, and take your corrections into account.
  • Generating memory from records: an automated nightly process, and summary creation when comparison material is missing, send the worded parts of roughly the preceding 90 days of records, saved memories, and correction and deletion history to describe usual patterns. Candidate text and its source context are also sent for a safety check. When AI memory is enabled, content that passes the safety check is saved automatically without individual approval. AI action permission settings apply to actions within chat. Turning AI memory off stops this automated processing.
  • Measures: by default, OpenAI does not use data transmitted from the Service via its API to train AI models. Transmitted data is deleted after a limited period under OpenAI's API data retention policy (see OpenAI's Privacy Policy for details)
• Anthropic, PBC (AI analysis service) — United States
  • Information transmitted: the text of your in-app feedback
  • Purpose: automatically categorizing in-app feedback
  • Measures: by default, Anthropic does not use data transmitted from the Service via its API to train AI models. Transmitted data is deleted after a limited period under Anthropic's data retention policy (see Anthropic's Privacy Policy for details)
• Apple Inc. (speech recognition) — United States
  • Information transmitted: voice data when you use voice input (only when it cannot be processed on the device)
  • Purpose: converting speech to text when you use voice input on iOS
  • Measures: on-device processing is preferred; transmitted voice data is handled under Apple's privacy policy (see "Notes on voice input" below)
• Google (speech recognition) — location depends on device settings
  • Information transmitted: voice data when you use voice input
  • Purpose: converting speech to text when you use voice input on Android
  • Measures: transmitted voice data is handled under Google's privacy policy (see "Notes on voice input" below)
• RevenueCat, Inc. (subscription purchase management) — United States
  • Information transmitted: your user ID (uid) and purchase status
  • Purpose: managing the purchase status of the paid plan (subscription) and reflecting it for the purchasing user
  • Measures and notes: no health data such as your symptoms is transmitted. To correctly reflect purchase status for you, your user ID is transmitted whether or not you make a purchase
• Google LLC (BigQuery: feedback analytics and AI usage analytics) — U.S. company (stored in Japan)
  • Information transmitted: in-app feedback (text, category, submission date, and the like, together with your user ID), and records of your AI feature usage (your user ID together with technical information such as the number of AI calls, token counts, and response times; these records do not include chat text or health data such as your symptoms)
  • Purpose: aggregating and analyzing in-app feedback, and understanding AI feature usage (to maintain and improve the Service and manage its operating costs). Viewed only by our operator
  • Measures: stored in Japan (Tokyo region, asia-northeast1). When you delete your account, the feedback analytics copy and the AI usage records containing your user ID are also deleted promptly (see Section 7)

External services that do not receive personal data

We use the following service to provide the Service, but no personal data of yours is transmitted to it.

• Open-Meteo (weather information) — Switzerland (OpenMeteo GmbH): to retrieve the weather and barometric pressure for your area, we transmit only latitude/longitude rounded to a coarse area (about 11km), via Cloud Functions (our server) rather than directly from your device — so your device's IP address is never exposed to Open-Meteo. We do not transmit information that identifies you (such as your user ID or account information). We treat this rounded coordinate, sent without any identifier, as not personal data on its own.
• Store review feature (Apple on iOS, Google on Android): when we request a store rating in-app, the OS's standard review screen is shown. This feature does not transmit your personal data (such as symptoms, records, or your user ID). Only the review content you enter yourself is sent to Apple / Google in accordance with each store's policy.

Notes on voice input

• When you use voice input, your voice data is converted to text through the OS speech-recognition service (Apple on iOS, Google on Android).
• On iOS, on-device processing is preferred. Only when your device does not support it may voice data be processed on Apple's servers.
• On Android, depending on your device and OS settings, voice data may be processed on Google's servers.
• See each company's privacy policy:
  • Apple: https://www.apple.com/legal/privacy/
  • Google: https://policies.google.com/privacy

6. Joint Use

We do not jointly use personal data with any other party (a specific arrangement defined under the APPI).

7. Retention Periods

• Symptom and other records, AI conversations, AI memory, and settings: retained while your account exists, and deleted promptly when you delete your account.
• AI memory correction and deletion history: up to 100 changes from the last 90 days are used to give AI context about updates and deletions. When memory is saved, history exceeding the time or item limit is removed. A daily automated process also deletes history older than 90 days, including when no memory is saved or AI memory is off. History may remain in storage until deletion completes, but history older than 90 days is not used for AI generation. All of this history is also deleted when you delete your account.
• Daily weather and pressure stored per user (see Section 5): retained while your account exists, and deleted when you delete your account.
• Push notification delivery tokens (see Section 5): kept per device on which you allowed notifications, invalidated when you sign out (if the device is offline when you sign out, the invalidation completes the next time you open the app with a connection), and deleted when you delete your account.
• Recent access history of rounded areas, kept to prevent abuse (up to 20 entries, see Section 5): older entries are overwritten as new ones are recorded, and it is retained only while your account exists. It is deleted when you delete your account.
• In-app feedback: retained while your account exists, and deleted promptly — including the analytics copy (data in BigQuery) — when you delete your account.
• AI feature usage records (data in BigQuery): records containing your user ID are automatically deleted after at most 400 days, and are deleted promptly — without waiting for that period — when you delete your account. Only daily and monthly statistics that do not contain user IDs (totals, averages, distributions, and similar figures not linked to any specific user) are retained as operational records of the Service.
• Data transmitted to the AI analysis services (OpenAI, Anthropic): deleted after a limited period under each provider's data retention policy. By default it is not used to train AI models (see Section 5).
• Crash diagnostics and usage data: retained until the retention period of the respective analytics tool (Firebase Crashlytics / Analytics) expires. After account deletion, data already transmitted remains within those tools until their retention periods expire, although it is deleted from the databases we manage.
• Purchase records of the paid plan (subscription): retained by the purchase-management provider (RevenueCat) and by Apple under their respective policies (see the exceptions in Section 8).
• Audit records of data access by our operators and systems: we retain the fact that our operators or server programs accessed your records (your user ID, the identifier of the record accessed, the type of access (read or write) and its search conditions (such as record type or date range), the time, and who accessed it) for at most 400 days, so that we can verify after the fact whether any insider viewed or tampered with records improperly. The content of the records (such as symptom descriptions or values) is not included. Your own reading and writing of your records from the app is not recorded. These audit records remain until the retention period expires even after you delete your account (see the exceptions in Section 8).

8. Your Rights (Disclosure, Correction, Deletion, and Suspension of Use)

You may request disclosure, correction, addition, deletion, suspension of use, or suspension of third-party provision of your personal information.

• Deletion: you can delete your account from the app's settings screen. When you delete your account, your record data held by us — including the analytics copy of your in-app feedback — is deleted promptly. The following are exceptions that remain after deletion:
  • Subscription purchase-management information: RevenueCat, Inc., our purchase-management provider, retains your user ID whether or not you made a purchase, and your purchase status if you did (no health or symptom records are included). If you made a purchase, Apple also retains transaction records. Also, deleting your account does not automatically cancel your subscription. To stop being charged, cancel it yourself in the App Store subscription management screen.
  • App usage data: data already transmitted to the analytics tool (Firebase Analytics) before deletion is removed from the databases we manage, but remains within the tool until its retention period expires (no health or symptom records are included).
  • A record that your account deletion was completed (your user ID and the deletion timestamp only): retained permanently to prove that deletion was completed and to prevent writes from resuming with old credentials after deletion (it contains no health or symptom records or other content).
  • Audit records of data access by our operators and systems (your user ID, the identifier of the record accessed, the type of access and its search conditions, the time, and who accessed it only): retained for at most 400 days so that we can verify after the fact whether any insider viewed or tampered with records improperly (see Section 7; they contain no health or symptom records or other content).
• Disclosure, correction, suspension of use, and other requests: please contact us at the address in Section 1 (support.seren@gmail.com). After verifying your identity, we will respond without delay as required by law. No fee is charged.
• Complaints: complaints about our handling of personal information are accepted at the contact in Section 1. You may also consult the Personal Information Protection Commission of Japan (https://www.ppc.go.jp/).

9. Security Measures

We take the following measures to prevent leakage, loss, or damage of the collected information and otherwise manage it securely.

• Technical measures: encryption in transit (TLS) and at rest. Access controls (through Firestore Security Rules, each user can access only their own data — no one can access another person's data). Safety checks on AI responses (multi-layered checks designed to prevent the output of medical advice)
• Organizational and personnel measures: access to the collected information is limited to us (the developer/operator), and handling practices are reviewed regularly
• Physical measures: data is stored on an access-controlled cloud platform (Google Cloud / Firebase) (see Section 5 for storage regions)
• Supervision of service providers: providers are selected after confirming their security standards and data-handling terms, and are appropriately supervised under their terms and data-processing conditions
• Awareness of the external environment: for providers located outside Japan, we take security measures with an understanding of the data-protection regime of the relevant country (see Section 5)

10. Children

The Service is intended for persons 16 years of age or older, and we do not intend for persons under 16 to use the Service or to collect personal information from persons under 16.

11. Tracking

• The Service does not perform tracking for advertising or behavioral targeting (tracking users across apps).
• The Service does not provide a web-browser-based service, so there is no context in which it would respond to browser "Do Not Track" signals.
• We do not share collected information for third-party advertising.

12. Revisions

We may revise this Policy as necessary. For material changes (such as additions to the information collected, the purposes of use, or the recipients), we will announce the change on the Service and, where necessary, ask for your renewed consent.

13. Note on AI Use

The Service's AI features assist in organizing your records and in conversation; they do not provide medical diagnosis, treatment, or advice. See the Terms of Service for details.

14. Language

The Japanese version of this Policy is the original and controlling version. This English version is a translation provided for reference, intended to convey the same content as the Japanese version. If there is any discrepancy between the Japanese version and any translation, the Japanese version prevails.