Privacy Policy
Last Updated: September 29, 2026
AI Diary (the “App”) is provided by Professional Effect Inc. This Privacy Policy explains how the App handles information. For our corporate policy, see https://www.pro-effect.jp/privacy_policy/.
1. Information We Handle
The App handles the following information to provide services and improve user experience.
1.1 Account Information
- What: Email address, user ID, display name
- How: Through Firebase Authentication during user registration
- Where: Firebase (Google Cloud Platform)
1.2 Diary Data (On Device)
- What: Diary content, attached images, conversation logs, creation timestamps
- How: User input within the app and conversations with AI
- Where: Only on your device (Local database: SQLite)
Important: We do not store diary bodies or images on our servers. In the normal path, conversation content and profile details are sent to the Google Gemini API through our server (see 1.6). The app does not contain an API key.
1.3 Profile Information (On Device)
- What: Nickname, birth date (for age), gender
- Where: On your device
- Use: Included in AI prompts for chat and diary generation
1.4 Points and Purchases
- Points: Balance and history (may use Firebase Firestore)
- Purchases: Subscription status via RevenueCat / the App Store
1.5 Voice Data
- What We Collect: Voice input during voice conversation mode
- How It's Processed: Speech recognition uses the OS standard functionality (Apple Speech Framework on iOS, Google Speech Recognition Service on Android)
- Data Storage: The App does NOT store any voice/audio data. Voice is converted to text in real-time, and only the transcribed text is stored as conversation logs on your device.
- OS-Level Processing: Speech recognition processing may be performed on Apple or Google servers. The handling of voice data in such cases is governed by each company's privacy policy.
- Text-to-Speech (Read Aloud): AI responses are read aloud using the OS standard text-to-speech feature. No data is sent to external servers for this purpose.
1.6 AI Conversation Data
- Normal path: Conversation and diary text are sent to the Google Gemini API through our Cloud Functions. We send conversation content, profile details, and cue summaries for sources you turned on
- API key: The app does not contain a generative AI API key. The key stays on our server
- Storage: We do not store generated text on our servers. Diary bodies and conversation logs stay on the device
- When the cloud is unavailable: A supported device uses its OS model (Apple Intelligence on iOS, Gemini Nano on Android). That conversation is not sent to a generative AI API
1.7 Optional On-Device Signals (Deferred Permission)
We request OS permissions only when you turn each source on in Settings—not at first launch. Denying all of them still leaves the traditional conversation diary fully usable.
- Calendar (EventKit, etc.): Same-day event titles/times used on-device as diary cues
- Photo Library: Metadata only (e.g. capture time). Image bytes and thumbnails are not read or sent
- Health (HealthKit): Steps, sleep, and workouts are read-only (no write). Detailed numbers are converted to qualitative labels on-device
- Storage: Aggregated signals stay on your device
- Off-device: In the normal path, cue summaries are sent to the Gemini API with the conversation. When the cloud is unavailable and the on-device model is used, cues stay in that on-device prompt. Raw calendar/photo/health payloads and image binaries are not stored on our servers
2. How We Use Information
We use the collected information for the following purposes:
- Providing app functionality (diary creation, voice conversation diary creation, management, viewing)
- Providing text input via speech recognition
- Reading aloud AI conversation content
- User authentication and account management
- Operating the points system and preventing fraud
- Providing AI-powered diary generation services
- Using optional on-device signals (calendar, photo metadata, health) as diary cues
- Improving app quality, fixing bugs, and developing new features
- Customer support
- Responding to violations of terms of service
3. Third-Party Services
The App uses the following third-party services. Each service processes data according to its own privacy policy.
3.1 Firebase (Google Cloud Platform)
- Information Shared: Account information, points information, device information
- Purpose: User authentication, database management, app stability improvement
- Privacy Policy: https://policies.google.com/privacy
3.2 Google Gemini API and the on-device model
- Normal path: Conversation content, profile details, and cue summaries are sent to the Google Gemini API through our Cloud Functions. The app does not contain an API key. We do not store generated text on our servers
- When the cloud is unavailable: Apple Intelligence or Gemini Nano on a supported device handles the request. That conversation is not sent to a generative AI API
- Terms of Service: https://ai.google.dev/gemini-api/terms
3.3 Apple Speech Framework / Google Speech Recognition Service
- Information Shared: Voice input during voice conversation mode (real-time processing only)
- Purpose: Converting speech to text (speech recognition)
- Data Storage: The App does not store voice data. OS-level processing is governed by each company's privacy policy.
- Apple Privacy Policy: https://www.apple.com/legal/privacy/
- Google Privacy Policy: https://policies.google.com/privacy
3.4 AdMob (Advertising Service)
3.4 RevenueCat
Important: Diary bodies and images are not stored on our servers. In the normal path, conversation content is sent to the Google Gemini API through Cloud Functions. When the cloud is unavailable, an on-device model processes it instead.
4. Data Storage Location and Retention Period
4.1 Local Data (On Device)
- Applies To: Diary content, attached images, conversation logs
- Retention Period: Until you uninstall the app or manually delete the data
- Backup: You can export data using the export function and save it to any cloud storage (Google Drive, iCloud, etc.)
4.2 Cloud Data (Firebase)
- Applies To: Account information, points information
- Retention Period: Until you delete your account
- Deletion Method: Execute "Delete Account" from the settings menu in the app to delete all cloud data
5. Data Security
The App implements the following measures to protect your information:
- Secure user authentication via Firebase Authentication
- Access control through Firebase Security Rules (preventing unauthorized points modification)
- On-device storage of diary bodies (not stored on our servers)
- HTTPS encrypted communication
- Regular security updates
6. Your Rights
You have the following rights regarding your personal information:
6.1 Right to Access and Export Data
- Export diary data in JSON format using the "Backup" function in the app
- View account information from the settings screen
6.2 Right to Modify and Delete Data
- Edit or delete individual diary entries
- Delete all local data using the "Delete Data" function in the app
6.3 Right to Delete Account
Execute "Delete Account" from the settings menu to delete:
- Account information stored in Firebase
- Points information and history
Note: Diary data stored locally will remain on your device. To completely delete it, also use the "Delete Data" function.
6.4 Right to Data Portability
- Transfer data to other devices using exported JSON files
7. Children's Privacy
The App does not have age restrictions. However, if users under 13 years of age use the App, parental consent must be obtained.
8. Changes to This Privacy Policy
This Privacy Policy may be changed without notice due to legal amendments or service changes. In case of significant changes, we will notify you through in-app notifications or email.
The latest Privacy Policy is always available at:
9. Contact Us