Morning letter
A little nod to yesterday.
Your interests and small moments from your diary give Hiyori something to remember and bring up in a future letter.
Morning. Evening.
A little letter.
A familiar voice.
Write a little about your day, whenever you like. Hiyori, an AI character, remembers moments from your diary and sends personal voice letters in Japanese.
Listen to Hiyori Plans and free trialiOS / Android · Coming soon · Japanese only
WITH A LITTLE VOICE
A little hello from Hiyori.
Get a feel for the voice in your letters. Listen to a short sample in Japanese.
Hiyori is an AI character with a synthesized voice, not a real person.
Sample transcript (Japanese)
はじめまして、ひよりだよ。朝のおはようも、夜のおつかれさまも。これから、あなたに声の便りを届けるね。なんでもない毎日が、ちょっと楽しみになったら、うれしいな。
An ordinary day.
A letter just for you.
Evening letter
Something to write about tonight?
A familiar topic or a prompt to reflect on your day. Set separate delivery times for morning and evening.
Your diary
A line, whenever you like.
Writing is optional: one entry a day, up to 500 characters. Letters still arrive on days you do not write, and you can listen again later.
A LITTLE EVERY DAY
Try seven days with a little voice in them.
7 days, all features
Your free trial never turns into a paid subscription automatically.
¥980/ month, tax included (Japan)
If you want to continue after your trial, purchase the monthly plan. Purchased subscriptions renew automatically every month.
- Two voice letters a day: morning and evening
- Personal letters informed by your diary and memories
- Keep delivered text and audio without an expiry date
The trial starts with your first delivered letter. When the trial or paid period ends, new generation stops; delivered letters remain. Cancel through the store where you subscribed. Deleting the app or account does not cancel your subscription.
Purchase and cancellation details ↗Know where your diary goes.
The profile, diary and extracted memories needed for your letters are sent to Google Gemini API. Generated letter text is sent to ElevenLabs for speech synthesis; audio is stored in Cloudflare R2. Letters may include information derived from your diary.
Consent to AI processing is required before use. Delete diary data or withdraw consent in Settings. Withdrawal stops AI processing and prevents app use; it does not automatically delete stored data.
Read the privacy policy →Before your first letter
Do I need to write every day?
No. Write whenever you want to. Without a diary entry, Hiyori draws on your profile and interests.
Can I talk with Hiyori in real time?
Koehiyori delivers morning and evening letters. It does not provide live voice calls or chat.
Does turning off notifications stop letters?
No. During your active trial or subscription, letters are still generated and available in the app. Generation and notifications may be delayed by connectivity or service conditions.
Why is the app for adults aged 18 or older?
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. The app and voice letters are currently Japanese only. Sign-in and consent to AI processing are required. It is not a medical, diagnostic or counseling service.