"Mononoke" is a supernatural horror anime that delves into the world of spirits, curses, and human emotions. The protagonist, known only as the Medicine Seller, is a mysterious and enigmatic figure who travels through feudal Japan, exorcising malevolent spirits known as mononoke. To defeat these entities, he must uncover their Form, Truth, and Reason—three essential elements that reveal the spirit's nature and origins. The Medicine Seller wields a mystical sword, which can only be drawn once these elements are fully understood.

The series is structured into five distinct arcs, each focusing on a different mononoke and the human circumstances that gave rise to them. In the first arc, "Zashiki Warashi," the Medicine Seller encounters a haunted inn where a pregnant woman and her unborn child are tormented by a vengeful spirit. The second arc, "Umibōzu," takes place aboard a ship plagued by a sea spirit, revealing the dark secrets of its passengers. The third arc, "Nopperabō," explores a cursed household where faceless spirits reflect the family's hidden guilt and betrayal. In the fourth arc, "Nue," a noblewoman's jealousy and obsession manifest as a monstrous creature. The final arc, "Bakeneko," ties back to the Medicine Seller's origins, as he confronts a cat spirit linked to a tragic tale of betrayal and revenge.

Each arc is meticulously crafted, blending psychological horror with intricate storytelling. The Medicine Seller serves as both an exorcist and an investigator, unraveling the complex emotions and moral ambiguities that bind humans and spirits. The series emphasizes the interplay between human actions and supernatural consequences, often highlighting themes of guilt, regret, and the cyclical nature of suffering. The animation style, characterized by vibrant, surreal visuals and a distinctive use of color and pattern, enhances the eerie and otherworldly atmosphere.

"Mononoke" stands out for its unique narrative structure, rich symbolism, and exploration of the human psyche through the lens of supernatural phenomena. The Medicine Seller remains an enigmatic figure throughout, his motives and past shrouded in mystery, adding to the series' intrigue. By blending folklore, horror, and psychological drama, the series offers a compelling and thought-provoking examination of the darker aspects of human nature and the spirits that arise from them.