Katsuyokei: Conjugation

Japanese Forms & Drills

Only for iPhone

Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.

iPhone

Verb forms come from rules, not from memory. Drill them until 書いて arrives before you have finished thinking about it. Katsuyokei drills Japanese conjugation until it becomes automatic. Knowing that the te-form exists is not the same as producing 書いて without stopping to think. The first is understanding; the second is a reflex, and a reflex is built by repetition and feedback, not by explanation. WHAT YOU PRACTICE Verb classes — godan, ichidan, and the irregulars. Including the verbs that look like one class and behave like another: 帰る, 入る, 走る and 切る end in -る and are godan, and that is exactly where most mistakes live. Every form you actually need: polite ます forms, the plain negative, the plain past, the te-form and its sound changes, conditionals, potential, volitional, imperative, prohibitive, passive, causative, and the causative-passive along with its spoken contraction. Adjectives too — both kinds, including いい, which stops behaving like an adjective the moment you negate it. FIVE WAYS TO BE ASKED Pick the right form from four options. Type the form yourself. Name a form you are shown. Name the conjugation class. Take a conjugated word back to its dictionary form. The app moves you along that ladder on its own: a form you have just met starts with multiple choice, because typing something you have never seen is guessing, not practice. WHEN YOU GET IT WRONG You see the transformation, not a red cross. 書く → 書か + ない → 書かない, with one line explaining the rule underneath. No paragraphs in the middle of a session. WRONG ANSWERS THAT TEACH The distractors are the mistakes learners actually make. Practice the te-form of 帰る and you will be offered 帰て — the answer you would give if you thought it were an ichidan verb. MASTERY YOU CAN TRUST Three lucky answers do not show mastery, and five hundred wrong ones do not either. Progress is measured per form and per verb class separately, because the te-form of an ichidan verb and the te-form of a godan verb ending in ぐ are not the same skill. Sessions lean towards whatever you keep getting wrong. SESSIONS THAT FIT Five questions by default, fifteen in a longer session. A minute or seven, one tap from opening the app. No setup, no daily quota to configure, no streak to protect at midnight — the streak survives a missed evening and breaks after a missed day. ENGLISH AND POLISH Interface and content switch independently, so a Polish menu with English grammar terms is a normal combination rather than a compromise. PRIVATE BY CONSTRUCTION Everything stays on your device. No account, no sign-in, no analytics, no advertising, no tracking. The app makes no network requests at all apart from handling the purchase itself. It works in aeroplane mode. FREE AND PREMIUM Levels 1 and 2 are free in full — enough to reach the te-form, which is the point at which Japanese starts connecting into sentences. Premium is a single purchase that opens levels 3 to 5, the full vocabulary pool and weak-form practice. No subscription. Also from the same author: Kaname — Japanese Grammar, for when and why a construction is used, rather than how to build it.

  • This app hasn’t received enough ratings or reviews to display an overview.

The session bar is full when the counter says you are done The bar counted finished questions while the label counted the one in front of you, so at „7 / 7” it still had a sliver left, and on the first question it was empty. Two ways of saying the same thing, disagreeing by exactly one question, half a centimeter apart. Reduce Motion now switches this app's animations off Seven things moved when you tapped them — readings appearing, translations appearing, level sections folding open — and all seven ignored the iOS setting. For some people that motion causes nausea and dizziness, so it is not a matter of taste. With Reduce Motion on, the same taps do the same thing, immediately and without travel. If clearing your progress fails, the app says so Resetting is the one thing here that cannot be undone, and it was the one thing that could not report a problem: the app closed the dialog and said nothing, whether it had cleared anything or not. A failure would have surfaced days later, on the progress screen, with no way to connect it to what caused it. Purchase messages follow the language you picked in the app Choosing Polish inside the app left a few sentences behind in the phone's language — the purchase errors, and the mastery bar labels read out by VoiceOver. They were reaching for the system's translations instead of the app's, so one screen could end up in two languages at once.

The developer, Jakub Dwojak, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

    Privacy practices may vary, for example, based on the features you use or your age. Learn More

    The developer has not yet indicated which accessibility features this app supports. Learn More

    Seller
    • Jakub Dwojak
    Size
    • 3.3 MB
    Category
    • Education
    Compatibility
    Requires iOS 18.0 or later.
    • iPhone
      Requires iOS 18.0 or later.
    • Mac
      Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
    Languages
    • English and Polish
    Age Rating
    4+
    In-App Purchases
    Yes
    Copyright
    • © 2026 Jakub Dwojak