Koehiyori Privacy Policy

Last updated: October 8, 2026

This policy explains how Roamcraft handles information in Koehiyori, an app that delivers letters written by AI and read with synthesized speech. The app is currently available in Japanese only.

1. Operator and contact

Roamcraft (person in charge: Yuya Tsuru)
MIEUX Shibuya Bldg. 8F, 5-3 Maruyamacho, Shibuya-ku, Tokyo 150-0044, Japan
[email protected]

2. Information we collect and why

Account information: email address, sign-in provider identifiers, user ID and email verification status, for authentication and account management. Passwords are managed by the authentication service.
Profile: nickname, interests and favorite things, to personalize letters.
Diary entries and memories: entries, dates and short AI-extracted memories, to select topics and generate personal letters. Writing a diary is optional.
Letters: generated text and audio, dates, read/playback status and saved-for-later status, for delivery, playback and history.
Settings and notifications: morning/evening times, time zone, notification permissions and notification tokens, for scheduling and push delivery.
Consent and purchases: consent time and policy version, trial start time, purchase identifiers, store transaction information and subscription status, for consent management, trial eligibility, purchases and restoration. We do not collect payment card numbers.
Usage and operations: diary saves, opens, playback, notification feedback, API usage, processing results, timestamps and hashed user IDs, to improve quality, investigate issues, prevent abuse and manage costs. Infrastructure providers may process technical information such as IP addresses.
Support: your messages and contact details, to respond, verify identity and handle privacy requests.

3. External services and information sent

Google Gemini API — text and memory generation: Receives the necessary parts of your profile, diary entries and extracted memories. Entries are processed to extract memories; relevant entries and memories are selected for letters. We do not send your entire diary history for each letter. User IDs, notification tokens, account email addresses and purchase information are not included as AI input fields. Information you type into free-text fields may still be sent as part of that text. Gemini API terms.
ElevenLabs — speech synthesis: Receives generated letter text, not the original diary or list of memories. Letters can nevertheless contain information derived from your diary or profile. ElevenLabs privacy policy.
Firebase / Google Cloud — authentication, storage, delivery and operations: Processes account details, profile, diary, memories, letter text, settings, notification tokens, consent, subscription and usage records. Push delivery uses Firebase Cloud Messaging. Firebase privacy information.
Cloudflare R2 — audio storage and delivery: Processes generated audio and storage identifiers. Audio is stored privately and delivered through expiring URLs after authentication. Cloudflare privacy policy.
RevenueCat / Apple App Store / Google Play — purchases and subscriptions: RevenueCat receives purchase identifiers and store transaction information to verify subscription status. It does not receive diaries, letter text or audio. The stores process payments. See the privacy policies of RevenueCat, Apple and Google.

4. AI consent and model training

Before use, we explain the recipients, information and purposes and obtain your consent to AI processing. This includes processing any diary entries you choose to write. If you do not write an entry, no diary entry is sent. Withdrawing consent in Settings stops subsequent AI processing and prevents app use. It does not automatically delete stored data; request deletion separately if desired.

We do not intentionally supply user data for AI training. Our operating policy is to use Gemini API Paid Services, whose terms state that prompts and responses are not used to improve Google's products. Limited retention may occur for abuse prevention and other permitted purposes. External providers, including ElevenLabs, handle retention and use under their contracts, settings and linked policies. We do not promise zero retention or zero training use across all providers.

5. Service providers, disclosure and overseas processing

We engage the listed providers as needed to fulfill these purposes. Except where permitted by law, we do not disclose personal data to third parties beyond these purposes without consent. We do not sell user data.

Providers may process or store data outside Japan, including in the United States, where privacy laws differ. The linked policies describe their handling and safeguards. Where required by law, we provide information and obtain consent for overseas transfers or establish safeguards through contracts or other arrangements. Contact us for information about processing locations and safeguards.

6. Retention and security

We retain profiles, diaries, memories and letters until deletion by the user, service closure or a similar event. Delivered letter text and audio have no automatic expiry and remain after a trial or subscription ends. We will announce data handling arrangements before service closure.

Operational logs, support correspondence and records needed for contractual or legal purposes are kept for the period needed to respond, prevent abuse and fulfill obligations. External providers' own retention policies apply to their records and backups.

We use authentication, access controls and encrypted communications to protect information. Our policy is not to include full diary entries, memories, letters or profile free text in application operational logs.

7. Deletion, access, correction and other requests

Deleting a diary entry also deletes its extracted memories. Use Settings → Privacy → Delete diaries and memories (「日記・Memoryを削除する」) to delete them together. Previously delivered letters are not rewritten.
Use Delete this letter (「この便りを削除する」) to delete its text and audio.
Use Settings → Privacy → Delete all data (「すべてのデータを削除する」) to delete your account, profile, diaries, memories, letters and audio.
After deletion, we retain a hash derived from a verified email address or sign-in provider identifier, together with the trial start time, to prevent repeated trials. We also retain the deleted user ID and deletion timestamp to prevent recreation of deleted accounts. These records have no automatic expiry and do not include diary text or audio.
If you cannot access the app, or wish to request account/data deletion, access, correction or suspension of processing, contact support. We may verify your identity and respond in accordance with applicable law. Never send a password.

Deletion is processed progressively and retried after failures. Records required by law may be retained as necessary. Account deletion and consent withdrawal do not cancel subscriptions. Cancel separately through the store where you purchased.

8. Age and information you enter

We limit the service to adults aged 18 or older to comply with the age requirements of Google Gemini API, which generates the letter text. See the Gemini API age requirements.

The service is for adults aged 18 or older. Do not use it if you are under 18. Do not enter other people's personal information, passwords, payment details or confidential information unnecessary for generating letters.

9. Policy changes

We will announce changes and their effective date on this page or through the service. If a material change to recipients, purposes or other terms requires consent by law, we will seek renewed consent.