If you’re looking for how to say “piece of shit” in Japanese, there isn’t a single perfect one-to-one phrase—the intensity and nuance depend on context. Here are common equivalents, from direct to more natural insults:

Direct / Strong Insults

  • クソ (kuso)
    Literally “shit.” Often used like “damn” or “crap,” but can be harsh depending on tone.

  • クソ野郎 (kuso yarō)
    Closest to “piece of shit” or “shitty bastard.” Very insulting and aggressive.

  • クズ (kuzu)
    Means “scum” or “worthless person.” Common and sharp insult, less vulgar than “kuso yarō” but still strong.

Slightly Softer or Situational

  • 最低なやつ (saitei na yatsu)
    “A terrible person” or “the worst kind of person.” Less crude, more socially acceptable.

  • ろくでなし (rokudenashi)
    “Good-for-nothing” or “worthless person.” Old-fashioned but still used.

Example

  • あいつはクズだ。
    “That guy is a piece of shit.”

Important Notes

  • Japanese insults are highly context-sensitive; tone, relationship, and situation matter more than the word itself.
  • Strong insults like クソ野郎 can sound very aggressive and are rarely used in polite conversation.
  • In everyday speech, people often choose milder phrasing or imply insults indirectly.

If you want, I can tailor it for anime-style, casual slang, or something that sounds more natural in real-life conversation.