Yumeko is invited to the Traditional Culture Research Society's clubroom just in time to witness Mary lose a high-stakes bet and adding 40 million yen to her debt. Yuriko Nishinotōin, Mary's opponent, a Student Council member and president of the Culture Club, then challenges Yumeko to the Life or Death game, introducing her to the only right of the Pets: to challenge anybody of their choosing to an "official match", which Mary had done just now...