The film tells the story of Niiro Tsurichiyo (Mifune) as the illegitimate son of a powerful nobleman, and the way of his life that made him a swordfighter but also a social outcast. He joins forces with the multiple clans against the Lord of Hikone, Sir Ii Kamonnokami Naosuke. Ii is the right hand of the shogunate and brought upon himself the wrath of the Satsuma, Mito, and Choshuu provinces after making an unpopular choice for the appointment of the 14th shogunate. Many critics arose after the controversial appointment, and Ii initiated the Ansei Purge to quiet critics of his choices. This, in turn, led to an assassination plot hatched by the three provinces in order to remove Ii from his position of power. The shoguns also weeding out Ii's spies from the plot. The film is based on a novel, which in turn was inspired by the historical Sakuradamon incident, in which the feudal lord Ii Naosuke was assassinated outside the Sakurada Gate of Edo Castle.
