Zatoichi runs afoul of some evil fugitives, working for a corrupt law official.

A decapitation at the hands of the shogun's monstrous misbegotten son kicks off the action and draws nomadic Nemuri Kyoshiro (Raizô Ichikawa) into more sword-fighting adventures when he's blamed for the beheading. Meanwhile, the head-chopper's mother is busy knocking off the shogun's lawful heirs to secure the shogunate for her son.

Blind swordsman Zatoichi, jailed briefly, is implored by another prisoner to aid him in proving his innocence of a crime for which he is sentenced to death. Zatoichi is reluctant to get involved, because he knows how often such involvement has led to trouble in the past. But events conspire to thrust him repeatedly into involvement, and gradually he comes to believe in the man's innocence and determines to free him.