Kanji Library
VerbsJLPT N1

恋する (koisuru) conjugation

JLPT N1 Irregular verb (Group 3)transitive (takes を)intransitive

to fall in love with, to love

恋する (こいする, koisuru) is an irregular verb. Only する and 来る are truly irregular, and every learner meets them in week one. Every form below is tappable — hear it, then say it back.

Conjugation table

FormPlain (casual)Polite (~ます)When you use it
Dictionary / plain
koisuru

koishimasu
The form you look up. Also the casual present and future.
Plain negative
koishinai

koishimasen
“doesn’t / won’t”. From here it conjugates like an i-adjective.
Plain past
koishita

koishimashita
The casual past — same ending as the te-form, with た/だ.
Plain past negative
koishinakatta

koishimasendeshita
“didn’t”. The negative past, still i-adjective-shaped.
Te-form
koishite
The connector: requests, linking clauses, ~ている.
Progressive (~ている)
koishiteiru

koishiteimasu
“is ~ing”, or an ongoing resulting state.
Desire (~たい)
koishitai

koishitaidesu
“want to ~”. Behaves as an i-adjective.
Volitional
koishiyou

koishimashou
“let’s ~” / “I think I’ll ~”.
Potential
koidekiru

koidekimasu
“can ~”. What you could do; the object often takes が.
Passive
koisareru

koisaremasu
“is ~ed”. Also the honorific and the suffering passive.
Causative
koisaseru

koisasemasu
Make or let someone do it.
Causative-passive
koisaserareru

koisaseraremasu
Be made to do it — the long one.
Imperative
koishiro

koishitekudasai
Blunt order. Use ~てください in real life.
Prohibitive
koisuruna
“don’t!” — dictionary form + な.
Conditional (~ば)
koisureba
“if ~”. General rules and hypotheticals.
Conditional (~たら)
koishitara
“if / when ~”. The everyday conditional.

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Why it conjugates this way

Only する and 来る are truly irregular, and every learner meets them in week one. See the full rules on the verb conjugation guide.

Kanji in this verb

Other JLPT N1 verbs

All JLPT N1 verbs →