How to say "craze" in Japanese

• ブームJLPT N1approx.Common
  noun, noun (suffix)A craze in the sense of a temporary wave of public enthusiasm — something suddenly and widely popular, like a fad or boom that everyone takes up for a while.
  小型車こがたしゃのブームは終おわろうとしている。↗

  The small car boom is ending.
• 流行りゅうこうJLPT N3approx.Common
  suru verb, intransitive verb, no-adjectiveA craze as what is in vogue at the moment — the prevailing fashion or trend people are following; it presents the thing as part of current style rather than as a sudden boom.
  あの種しゅの服ふくが今いま流行りゅうこうだ。↗

  That kind of dress is now in fashion.
• キチガイCommon
  noun, noun (suffix)For the everyday sense of 'craze', a passing fad, this is not the word you want: it means an obsessive enthusiast and is a highly offensive term for a madman; usually written in kana.

For a craze as a public fad or boom use 「ブーム」; for what is currently in fashion use 流行; 「キチガイ」 is an offensive word for an obsessive maniac, not a popular fad, and is best avoided.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• ブームboom
• 流行りゅうこうfashion
• 熱狂ぶりねっきょうぶりcraze
• 流行り物はやりものfashionable thing
• 流行りはやりfashion
• きちがいmania
• 熱ねつzeal
• 狂きょうmania