Ogami Itto is a master swordsman who holds a position of high power in the Tokugawa Shogunate. Highly trusted by the Shogun, he serves as the official decapitator, assisting lords and samurai who have been ordered by the Shogun to commit seppuku.

One day, Itto’s wife and members of his household are brutally murdered by a clan seeking to avenge their lord’s execution, which had been carried out by Itto. In the wake of the attack, two items are left in Itto’s home: his unhurt infant son, Daigoro, and a symbol meant to signify Itto’s betrayal of the Shogun.

Disgraced by the false symbol, Itto is labeled a traitor and forced to forfeit his position. He becomes a ronin, wandering the country with his son, searching for the men who killed his wife, seeking to clear his name and avenge her death.