The Medicine Seller wanders old Japan hunting mononoke, vengeful spirits formed when a human grudge fuses with a wandering ayakashi. Before he can draw his blade against one, he must uncover three things: its Form, the Truth behind the tragedy that created it, and the Reason it turned monstrous. Each encounter drags him into a fresh haunting, where he questions the living and the dead until the mononoke's true nature is exposed enough to be cut down.