A mysterious man called the Medicine Seller travels along feudal Japan, uncovering and slaying evil spirits called "Mononoke".

Mononoke follows a wandering, nameless character known only as the "Medicine Seller". The series is composed out of 5 story arcs, each featuring the medicine seller as he tries to solve the mystery behind the existence of various Mononoke, evil spirits that still linger in the human world. He combats them using his vast knowledge of the supernatural, but a Mononoke can only be slain after he uncovers its form (Katachi), the truth behind its appearance (Makoto) and the reason for its unusual behavior (Kotowari).—Anonymous