Koi Kioku is a Japanese learning app built around one idea: memory that lasts. Beni-sensei, your koi fish teacher, guides you through spaced repetition (FSRS) that schedules each card at exactly the right moment.
FREE FOREVER
• Hiragana & Katakana — complete recognition decks
• First Words & Emergency phrases
• Smart review scheduling that adapts to you
• A daily goal you set yourself, and a streak freeze each month if you miss a day
• Home Screen and Lock Screen widgets — see what's due without opening the app
• Works fully offline — your learning data never leaves your device
KOI KIOKU PRO
• Every deck unlocked — all levels and situations
• AI decks: type any topic ("ordering at a cafe") and get a 20-card deck made for you
• Oral practice: answer out loud, and Beni-sensei reacts in character — choose her personality, from fired-up coach to sharp-tongued critic to Kansai comedian
• Ask anything about Japanese while you study — or tap "Why?" right on an answer for an instant explanation
• Learning insights: review forecasts, accuracy trends, and your hardest cards
• 5 streak freezes a month instead of 1 — miss a day without losing your streak
• Audio on every card
A PATH, NOT A PILE OF DECKS
Follow one clear route from kana through everyday words to JLPT levels, and step off into real-life situations — restaurants, trains, hospitals — whenever you need them. Nothing is locked behind a previous step.
PROGRESS YOU CAN TRUST
"Known" here means a card you should still recall a week from now, not one you flipped once. Watch your known count grow, see how far you are through N5, N4 and N3, and find out which situations you're ready to practice. Collect badges along the way — and once you've earned one, it stays earned.
STUDY THAT FEELS ALIVE
Multiple exercise types (choice, listening, cloze, typing, matching), correct/wrong sounds, streaks, and a mascot who actually cares whether you remember.
PRIVACY FIRST
Your cards and progress stay on your device. No ads, no tracking, no analytics SDKs. Speech recognition for oral practice runs entirely on-device — audio never leaves your phone.
Subscription: Yearly $59.99 or Monthly $19.99. Auto-renews, cancel anytime in Settings.
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