Twin sisters Lara and Kiki, heiresses of the Hoshino conglomerate, had lived comfortably in a luxurious mansion near central Tokyo, attended since high school by maid Maami and butler Tanaka. One day, returning home from school, they receive a letter from their mother, Tsumiki—the "Lady Queen" of the Hoshino family. Its contents are shocking, exposing a truth hidden from them since childhood. Their former father, Minoru, had betrayed Tsumiki and was consequently burned across his face and body with sulfuric acid, now kept alive in a maggot-like state in the mansion's basement. His death had not been due to a traffic accident, but punishment for his betrayal. Even more astonishing, Minoru had a secret child older than the twins—none other than Arita, Lara's current homeroom teacher. To promote the girls' independence, Tsumiki orders them to treat Arita as livestock, using him as their personal training tool. Having been raised under Tsumiki and Tanaka's strict BDSM discipline, Lara and Kiki immediately comply. With help from classmates Mio, Rui, Mai, and Mirei, they trap Arita, subject him to brutal torture, lock him in the gym storage room, and throw him into a public toilet. Unsatisfied, the sisters lure Arita to their home, imprison him in a closet, force him into oral servitude, and plot to transform him into a human golden toilet. Through this process, the full extent of Lara and Kiki's ruthless will—and Tsumiki's dark intentions—becomes chillingly clear.