: Mary, a bright scholarship student from a modest background, arrives at Hyakkaou only to realize that academic merit is secondary to gambling prowess.
: To survive, Mary teams up with her childhood friend Tsuzura Hanatemari , a "pet" who has lost her gambling spirit, and Yukimi Togakushi , the president of the Literature Club, to establish their own gambling den.
: On her first day, Mary is challenged by Kokoro Aiura and nearly falls into debt, which would force her into the "House-pet" status—a system of social servitude for students who cannot pay their debts.
: Mary faces off against Sachiko Juraku , a sadistic Student Council member who is fascinated by Mary and wishes to break her spirit and make her a permanent "pet". Media Adaptations