Four ninja are hired to fight against the Shogunate’s plot to abolish the Gamo Clan, the regional barons struggling to reinstate their young heir Tanemaru as their Lord.

Aging samurai Hanshiro Tsugumo arrives at the home of Kageyu Saito and asks to commit a ritual suicide on the property, which Saito thinks is a ploy to gain pity and a job. Saito tells Tsugumo of another samurai, Motome Chijiiwa, who threatened suicide as a stratagem, only to be forced to follow through on the task. When Tsugumo reveals that Chijiiwa was his son-in-law, the disclosure sets off a fierce conflict.

While her son, Kichi, is away at war, a woman and her daughter-in-law survive by killing samurai who stray into their swamp, then selling whatever valuables they find. Both are devastated when they learn that Kichi has died, but his wife soon begins an affair with a neighbor who survived the war, Hachi. The mother disapproves and, when she can’t steal Hachi for herself, tries to scare her daughter-in-law with a mysterious mask from a dead samurai.