The retired Shōgun's youngest son, Lord Nariatsu, crosses into the neighboring Oshi fief while he's hunting.
Angered by this gross injustice, Chief Retainer (Chamberlain) Tatewaki approaches childhood friend, Sengoku Hayato, and asks him to avenge their Lord's murder.
They follow Nariatsu to Edo (feudal Tokyo) where they are joined by Ido Daijuro, a rōnin (wandering samurai) with a thirst for revenge against lords after tragic injustice to his family.
Hayato and his ten followers plan to ambush Nariatsu with his large escort as he travels from the brothels of Edo to the safety of his castle in the Tatebayashi fief.
As they are about to attack, Hayato receives a letter from Tatewaki ordering him not to kill Nariatsu, because Councilor Mizumo has told him that the council is likely to reverse the decision to abolish the Oshi fief.
His wife, Lady Orie, has already committed jigai in anticipation of Nariatsu's death and the retired Shōgun's wrath.