hara-kiri

noun3

1. •
   Ceremonial suicide by disembowelment, as by slicing open the abdomen with a dagger or knife: formerly practised in Japan by the samurai when disgraced or sentenced to death.
2. •
   Suicide or any suicidal action.
3. •
   (figurative) An act against one's own interests.

   • Regarded logically, therefore, Japan’s decision to go to war made no sense. It was hara-kiri. — 1982