Asylum. It is a Wonderland filled with peculiar residents. The Mad Hatter who always wears a hat, the Cheshire Cat who constantly smiles, the Queen who bosses everyone around, and the Caterpillar who can only squirm. Into this mysterious land comes Alice, a girl with a love for imagination. In 1889, England, while the serial killer "Jack the Ripper" is causing an uproar, Alice and her companions are living their usual strange days at an asylum on the outskirts of London. Then, one day, as Alice and the others are playing croquet, a commotion occurs. "The caterpillar is dead!" Only four people could have killed the caterpillar: Alice, the Mad Hatter, the Cheshire Cat, and the Queen. Alice is shocked, the Mad Hatter is confused, the Cheshire Cat smiles, and after some thought, the Queen solemnly declares, "If the culprit is among us, they must be caught immediately. We need to identify and restrain them." Everyone nods in agreement and decides to discuss the matter."

The year is Genroku, during the reign of Tokugawa Tsunayoshi. In a remote, snowbound village deep in the mountains, a body is discovered. The scene is gruesome—flesh from chest to abdomen has been savagely torn apart, as if by a relentless saw. Someone mutters: "The Saw Demon... It must be the Saw Demon’s doing..." As the cold rain continues to fall, sealing the village from the outside world, hidden motives and quiet fears begin to intertwine.