[3][4][5] Okada Izō is a rōnin born into poverty who joins the Kinnō-Tō [ja], a group of Imperial loyalists based in Tosa and headed by Takechi Hanpeita.

He is then ordered to assassinate the aristocrat Anegakōji Kintomo [ja] outside the Sarugatsuji using the sword of Tanaka Shinbei.

During his interrogation over Anegakōji's death, Tanaka commits harakiri after his recovered sword is presented to him as evidence.

As Hanpeita becomes increasingly determined to succeed in his plan to become daimyo of Tosa by eliminating his opponents, it becomes necessary to sacrifice Izō, which he does by betraying him after he is arrested as a rōnin by the Aizu Mimawarigumi and later by trying to poison him with amygdalin-drugged sake (座枯らし).

Izō survives, but, disillusioned, confesses to his murders for the Kinnō-Tō, and is condemned to crucifixion.