Kaeru

Kaeru is a calm, focused way to learn Japanese grammar, from your first particles to JLPT N1.

Over 400 grammar points are laid out like a train map. Each JLPT level is a line and each point is a station. Learn one or two new points a day, then keep them with spaced-repetition reviews that bring each point back just before you’d forget it.

ONE DAILY ROUTINE
Today shows exactly what to do:
• Learn: today’s new grammar, with clear explanations and example sentences, then a short quiz
• Review: grammar that’s due, as fill-in-the-blank sentences
• Flashcards: your own decks
• Immerse: reach your daily study-time goal
One button always takes you to the next step, and your streak counts any study you do.

REVIEWS THAT TEACH
• Type the missing grammar. Romaji turns into kana as you type, and Japanese keyboards work too.
• Sentences rotate, so you learn the grammar instead of memorising one example.
• Furigana on every sentence.
• Gentle “Close!” retries for near misses like typing “wa” for は.
• Undo a slip with one tap.
• Scheduling uses FSRS, a modern spaced-repetition algorithm.

BRING YOUR FLASHCARDS
Import decks exported from Anki (.apkg / .colpkg) with their media and review history, and study them alongside your grammar. You can also make your own cards and decks, and export them back out.

TRACK YOUR STUDY TIME
A simple start/stop timer for immersion, study or your own activities, with daily and weekly totals and a 7-day chart. You can start and stop it from Siri and iOS Shortcuts without opening the app.

MADE TO KEEP YOU GOING
• Kaeru the frog cheers you on
• Friendly reminders timed around when you usually study
• Light and dark mode

PRIVATE BY DEFAULT
Kaeru works fully offline with no account. If you want, sign in with Apple, Google or email to back up your progress and pick it up on another phone. No ads, no tracking.