Fujieda Baian is admired during the day as a skilled acupuncturist. However, at night, he is a highly skilled assassin, taking on contracts to quietly eliminate those whose existence is deemed toxic to society. Baian's latest target, assigned by his boss Otowa, is Shirakoya Kikuemon, the head of a powerful organization in Osaka.

In the past, Baian had been indebted to Shirakoya, but due to a conflict involving the swordsman Kosugi Jūgorō, their relationship has turned adversarial. After his lover is abducted, Shirakoya storms into Edo. With his life now targeted, Baian resolves to confront Shirakoya in a desperate final showdown.