The Medicine Seller traverses feudal Japan, on the hunt for malevolent spirits referred to as "mononoke". His expertise in the occult makes him a formidable adversary, but prior to vanquishing these entities, he must first uncover their Form, Truth, and Reason, as well as wield the potent Exorcism Sword. Before proceeding to the ultimate phase of destroying the spirit, the Medicine Seller must undergo a perilous initiation that involves meticulously analyzing his psychological state and scrutinizing the nature of the mononoke. While on his mission, the Medicine Seller finds an old-fashioned inn where Shino, a pregnant woman, seeks shelter. Despite the proprietor assigning Shino to the last unoccupied room, the room is plagued by a group of deadly mononoke known as the Zashiki Warashi. Using his intuition, the Medicine Seller delves deep into these vicious spirits to determine their Form, Truth, and Reason, and prevent them from claiming more lives.