Question

Why did Tametomo commit Harakiri?

Answer 1

After Taira cut Tametomo’s left arm limiting the use of his bow and then he was banished to the island of Oshima. He committed seppuku.

Answer 2

Seppuku was used voluntarily by samurai to die with honor rather than fall into the hands of their enemies, (and likely be tortured), as a form of capital punishment for samurai who committed serious offenses, or performed because they had brought shame to themselves.