Learn the system behind every Japanese verb.
Katsuyō teaches verb conjugation the way it actually works: one pattern of vowel rows, a few sound changes, and a handful of exceptions. Then it drills them with short games and brings each form back just before you forget it.
Free. No in-app purchases. iPhone, iOS 17 or later.
One verb, five vowel rows
Every godan verb conjugates by sliding along a row of the kana chart. Here is 書く (to write).
- a-rowか書かないnegative
- i-rowき書きますpolite
- u-rowく書くdictionary
- e-rowけ書けるpotential
- o-rowこ書こうvolitional
What's inside
Built for conjugation, nothing else
The godan system
Learn the rows once and every godan verb follows. Sound changes for the て and た forms (書いて, 読んで, 待って) and the irregulars する, 来る, 行く are taught as rules, not as lists.
FSRS reviews
Each verb and form is scheduled with FSRS, a modern spaced-repetition algorithm. Fast, correct answers push a card further out. Mistakes bring it back sooner.
Furigana and romaji
Turn furigana (kana above kanji) and romaji (Latin letters) on or off independently, so the app keeps up as your reading improves.
The verbs you need first
Verbs from the N5 and N4 levels across 17 forms, from ます and ない to conditional, passive and causative.
“Why?” and a weekly plan
After a wrong answer, tap “Why?” for a short explanation of the mistake: wrong vowel row, a missed sound change, the ichidan rule on a godan verb. Each week the app suggests a plan aimed at your weak spots, which you can accept or keep your current one.
No signal needed
Everything runs on your iPhone: lessons, all six games, reviews, explanations and your weekly plan. The app never connects to the internet.
Six drill games
Tap, swipe and trace. No typing.
- Pick the FormPick the right form. Every wrong option is a real, common mistake.
- Match PairsMatch dictionary forms to their conjugations and clear the board.
- Swipe SortSwipe each verb into godan, ichidan or irregular. It catches the tricky ones like 帰る.
- Chain LadderConjugate the previous answer, not the dictionary form.
- Kana TraceDrag through a grid of kana in any direction to spell the answer.
- Boss GauntletA mixed final round at the end of each unit, with lives and a boss to beat.
Privacy
Your progress stays on your iPhone
- No accountNothing to sign up for. Open the app and start.
- No ads or trackingNo analytics, no ad networks, and no data sold.
- On-device progressReviews, streaks and settings live only on your iPhone.
- Nothing leaves your iPhoneThe app makes no network requests and collects no data. Read the privacy policy.