きちがい

noun, noun, used as a suffix

mania; craze; obsession; enthusiast; fanatic

Used as a suffix or standalone noun to indicate an extreme obsession or enthusiast. Often derogatory or self-deprecating, e.g., 釣りきちがい (fishing nut). Less sensitive than sense 1 but still informal and potentially offensive.

• 彼かれは筋きんトレきちがいで、毎まい日にちジムに通かよっている。

  He's a workout fanatic and goes to the gym every day.

• あの人ひとはゲームきちがいだから、話はなしが合あうよ。

  That person is a game maniac, so you'll get along.