During the day, Dr. Baian is the friendly and trusted village acupuncturist. At night, he becomes Baian, the assassin. Using his acupuncture needles as weapons, he takes on deadly assignments, killing evildoers with an undeniable skill and precision.
Baian and Hikojiro are hired to take on a revenge killing for a dying noblewoman, who wishes them to assassinate the psychotic low-rank samurai who cruelly murdered her daughter-in-law.