Ryunosuke Tsukue is an amoral samurai and a master swordsman with an unorthodox style. He is first seen when he kills an elderly Buddhist pilgrim who prays for death, a moment that makes clear he feels no real emotion or empathy. Later, he defeats an opponent in a fencing contest that was meant to be non-lethal, but the match turns into a duel after he coerces his opponent's wife to sleep with him in exchange for throwing the match and letting her husband win. The other man discovers the affair before the contest and, against that backdrop, receives a notice of divorce as a grim prelude to the clash.
During the match, Ryunosuke commits an illegal lunging attack after the judge proclaims a draw. Yet the better swordsman parries and delivers a single, decisive stroke with his bokken, sending his rival to the ground. He flees town amid the chaos, cutting down many of the vanquished man’s clan members as he escapes. The vanquished opponent’s ex-wife asks to join him on the road, a hollow sign of the life he now leads.
Two years pass, and to survive he joins the Shinsengumi, a semi-official police force made up of rōnin who support the Tokugawa shogunate through murder and assassinations. In every encounter, whether he is killing or at home with his mistress and their baby son, Ryunosuke remains emotionally imperturbable, a man who seems impervious to fear or doubt. Eventually he learns that the younger brother of the man he killed in the fencing match is seeking revenge, and a duel seems inevitable. But two events shake his confidence before any confrontation can occur: a botched assassination attempt brings him face to face with another master swordsman, Shimada Toranosuke, in action, and for the first time he questions whether his own skill is truly unbeatable. The same night, his mistress—oh, the unnamed woman who shares his life—tries to kill him in his sleep, and he kills her in the gardens, the sleeping child inside the house crying out as the violence unfolds.
He returns to the gang of assassins at an oiran house in the Shimabara district of Kyoto. In a quiet, haunted room, he begins to see the ghosts of all the people he has killed. He is haunted by Shimada’s admonition: “The sword is the soul. Study the soul to know the sword. Evil mind, evil sword.” The final blow comes when he realizes that the apprentice oiran sent to entertain him is the granddaughter of the pilgrim he murdered at the film’s beginning.
With this grim realization, Ryunosuke spirals into a frenzy, slashing at the shadows and attacking his fellow assassins as a growing crowd of enemies closes in. He kills dozens of gang members as the flames of the brothel burn around him. Bleeding and driven by rage, he lunges forward one last time, and the film ends with a freeze-frame of him caught mid-sword-slash.
