In the Edo period, a 7-year-old girl is abandoned by her mother in a thunderstorm, and is blinded by a thunderbolt that falls close to her. Yasuke protects her, and becomes her foster-father, until he is killed by some roving men. A Ronin named Ukita protects her next, and teaches her to use a cane-sword for her protection. Combined with her good hearing, her fencing will prove fateful for her enemies (a rapist, cheating dice players, and bandits) as she tries to protect another girl who was sold into slavery by her indebted father.