Plot synopsis: Children from influential families in politics and businesses attend the Hyakkaou Private Academy. There, the hierarchy are classified by a series of games. Students that win are on the ruling side and the ones who lose become slaves. One day, a mysterious girl, Yumeko Jabami, transfers to Hyakkaou. She looks pure and pretty, but she's actually a compulsive gambler and seeks out the thrill of taking calculated risks.