hara-kiri

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.

On the downfall of his power in 1867 he was urged by one of his Council to save the honour of his family by a voluntary suicide. He flatly refused to do so and left the room, whereupon his faithful adviser retired to another part of the castle and solemnly performed the hara-kiri.

Suicide or any suicidal action.

...the report that was issued at the time officially blamed a disgruntled crewman who had been accused of theft and may have decided to do the ultimate hara-kiri, but quite how you prove that I don't know...

An act against one's own interests.

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

They are haunted by the spectre of the 1984 election, when Mr Walter Mondale committed hara-kiri by acknowledging the need to raise taxes if America were to get its economy straight.