The sadistic daimyo Tadanaga Tokugawa has decreed Japan's first martial arts competition using real swords, a move that appalls even his most loyal retainers. However, when spectators realize the opening match pits the one-armed Gennosuke Fujiki against the blind and lame Seigen Irako, even those with the strongest objections declare the contest a farce and view the combatants' deformities as an affront to their station. Most attendees are unaware of the deep-seated hatred Gennosuke and Seigen hold for one another, which stems from their struggle to become the heir to the insane samurai Kogan Iwamoto, leader of the notorious Kogan-ryuu dojo. Their once-cordial rivalry for control of Kogan-ryuu and the hand of Kogan's daughter, Mie, quickly turns violent when one of the young warriors angers the master, triggering a chain of events that eventually leads to their severe injuries. Shigurui chronicles the decisions that led Gennosuke and Seigen to this desperate point, as well as the many lives ruined by the brutality of samurai culture.