Skip to content
JLPT N5Verb Forms

Irregular Verbs: する / くる(Group 3)

Japanese has just two truly irregular verbs: する (to do) and くる (to come). Their conjugations don't follow the vowel rules and must be memorized.

Grammar path · 練習

Practice this in the path

A short lesson: the pattern, its sentence anatomy, a quick quiz and a sentence to build.

Pro lessonUNIT 10 · VERB FORMS

Structure · 形

する and くる — memorize each form individually.

Examples · 例文

  • する → します / しない / した / して

    Suru → shimasu / shinai / shita / shite

    Do: polite / negative / past / te-form

    The core vowel changes (su → shi) across forms.

  • 来る(くる) → 来ます(きます) / 来ない(こない)

    Kuru → kimasu / konai

    Come: polite / negative

    The kanji 来 stays the same, but its reading changes: く → き → こ.

  • 勉強する → 勉強します / 勉強しない / 勉強した

    Benkyou suru → benkyou shimasu / benkyou shinai / benkyou shita

    Study: polite / negative / plain past

    Noun + する compounds conjugate exactly like する itself (su → shi).

Usage notes · 注意

  • The Power of する: attach する to a Chinese-origin or abstract noun to verbify it — 勉強 (study) + する = to study; 買い物 (shopping) + する = to shop.
  • Survival Tip: since there are thousands of "noun + する" verbs, mastering する conjugation instantly unlocks a huge portion of the dictionary.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones Irregular is tested against.

vsRegular う/る-verbs

Group 1 and 2 verbs follow predictable vowel/stem rules; する and くる do not — their stem vowels change irregularly (し/す, き/く/こ) and must be memorized.

More verb forms

Study Japanese grammar on LenGaki

Everything on this page, ready to study

  • 7,788 JLPT vocabulary words, N5 through N1, with readings and audio (N5 free)
  • 2,057 kanji with on'yomi, kun'yomi and stroke-order practice
  • 445 grammar points with examples and commonly-confused comparisons
  • Full-length N5 and N4 mock exams, timed, with real listening audio (N5 sets 1 and 2 free)