Koi Kioku is a quiet spaced-repetition app for learning Japanese — built for people who are tired of language apps that interrupt, upsell, and gamify more than they teach.
Download on the App StoreFree on iPhone · Kana & starter phrases free forever
Most drop-offs aren't your fault. When an app fills every session with ads, upgrade prompts, and busywork, stopping is the reasonable response. Koi Kioku takes the opposite bet: a short daily review, scheduled by an algorithm that knows when you're about to forget, and nothing else competing for your attention.
Every card is scheduled by FSRS, a modern spaced-repetition algorithm: you review a card shortly before you'd forget it, so minutes spent turn into memory that lasts. A single clear path takes you from hiragana and katakana through everyday words to JLPT N5, N4 and N3 — and you can step off into real-life situation decks whenever you need them. Nothing is locked behind a previous step.
Cards, progress, and review history live on your device and are never uploaded. Speech recognition for oral practice runs on-device too.
Study on the train, on a plane, anywhere. The free experience never needs a connection.
"Known" means a card you should still recall a week from now — not one you flipped once. Watch your real count grow through N5, N4 and N3.
Beni-sensei, a koi fish teacher, reacts to your answers in character — from fired-up coach to sharp-tongued critic to Kansai comedian.
No account, no trial clock
$59.99/year or $19.99/month
Prices in USD; local pricing may vary by region. Subscriptions auto-renew until cancelled — you can cancel anytime in your App Store settings, and access continues to the end of the paid period. Your learning data stays on your device whether or not you subscribe.
Yes. There are no ads and no advertising SDKs in the app. Koi Kioku is funded by the optional Pro subscription, not by your attention. See the privacy policy for the full picture.
At the beginning of the path: hiragana and katakana. The app schedules everything for you — you just show up for a short session each day. Both kana decks are free.
The path runs through JLPT N5, N4 and N3 vocabulary, and the progress screen shows how far you are through each level. The full JLPT level decks are part of Pro.
Nothing is taken away from your device. Cards and progress are stored locally, remain after a subscription ends, and are deleted only if you delete the app.
That's the whole ask. Beni-sensei handles the scheduling.
Download on the App StoreRequires iOS 17 or later