The disgraced shogun’s executioner, Ogami Itto, continues his journey along the Demon Way with his young son, Daigoro, in their concealed weapon-laden baby cart. Traveling through the Japanese countryside, they are stalked by underwater ninjas from the Yagyū clan before Ogami encounters a ronin named Kanbei. Kanbei, a masterless samurai burdened by a dishonorable past, challenges Ogami to a duel that ends in a draw, leaving Kanbei’s obsession with a true fight to the death unresolved.

Seeking refuge at an inn, Ogami witnesses the plight of a young woman forced into prostitution. When she kills her abusive pimp in self-defense, Ogami intervenes not with his blade, but by voluntarily enduring torture on her behalf to satisfy the yakuza who own her contract. His stoic endurance earns him the gratitude of the brothel’s owner, who hires him to assassinate a corrupt and sadistic chamberlain. The target is a high-ranking official whose cruel whims have destroyed the lives of many, including the brothel owner’s sister.

As Ogami prepares for the mission, he finds his path complicated by the chamberlain’s attempts to hire him for a counter-assassination and by the persistent presence of Kanbei, who has aligned himself with a trio of brutish mercenaries responsible for a horrific rape and murder that Ogami could not prevent. The narrative builds toward a massive confrontation on a mountainside, where Ogami and Daigoro face the chamberlain’s personal army of nearly a hundred soldiers. In the climactic battle, the baby cart reveals its hidden arsenal, including mounted firearms, as Ogami carves a bloody path through his enemies. Just as the battle seems won, Kanbei arrives demanding the duel to the death that was previously denied to him, forcing the two master swordsmen to resolve their deadly rivalry.