Hitokiri

Hitokiri is any one of numerous samurai in Japanese history who were amazingly strong and considered undefeatable by normal people. Hitokiri literally means "Person Slayer", but is better translated as assassin.

One of the most prominent Hitokiri was Kawakami Gensai[?], said to be totally undefeatable. Kawakami Gensai was the character model for Himura Kenshin in the anime Rurouni Kenshin.