During the Edo period in Japan, acupuncturist Dr. Baian (Ken Watanabe) uses his skills to kill or cure. In fact, Baian often accepts payment to extinguish evildoers — but only so that he can use the money to minister to the innocent sick. Think Robin Hood with needles and blades instead of a longbow. During the day, Baian (Ken Watanabe) 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 with an undeniable skill and precision. Is based on a series of books by Shotaro Ikenami.