Yataro Tanigawa, a one-eyed hired assassin, impresses yakuza boss Gomyo Kiyoemon with his skill. Gomyo hires Tanigawa as his bodyguard, or yojimbo, to protect him during an inter-clan conflict. Tanigawa quickly rises in stature in the clan, but finds his boss's enemies almost overwhelming.

Thief Yaheiji (Keizo Kanie) helped a dying young samurai (Hiroaki Murakami), after recovering, he lost his memory and returned to Edo under the name of Yataro Tanigawa. Yaheiji meets Yataro again in Edo, by which time Yataro has become a dark hunter (Hired Assassin). The boss of thieves to whom Yaheiji obeys is killed, and Yaheiji participates in the battle to take his place Yataro helps him defeat and save his life, and Yaheiji also tries to save Yataro from the world of assassins... The drama "Dark Hunter" is based on the novel by Shotaro Ikenami, who is best known for his TV series Onihei Hankacho, Kenkaku Shobai and Fujieda Baian's Shikake-nin. The film version directed by Hideo Gosha is well known, but this version is more faithful to the original.

Yaheiji, a bandit, rescued a samurai who was lying under a cliff. He was wounded with deep cuts by being attacked by someone and had no memory of the past. Yaheiji named him "Yataro Tanikawa", then left. One night, Yaheiji saw Yataro cutting down a person. Yataro still couldn't get his memory back and became a paid assassin under Seiemon. Yaheiji was scared and decided to help him recover his memory.