Seppuku

From Turtledove

Seppuku is a form of Japanese ritual suicide by disembowelment. A second was present to decapitate the suicide, and spare them the further pain of the disembowelment. In later years, the second was allowed to use a pistol. Seppuku is also known in English as hara-kiri, a term regarded as gross and vulgar in Japanese.

Commander Minoru Genda committed seppuku in 1943 when the United States reconquered its territory Hawaii from Japan.