Kujibiki♥Unbalance

Chihiro has been cursed with bad luck all his life, but all that changes when he wins a mysterious lottery that earns him a spot at the prestigious Rikkyoin High School, a strange place where everything is decided by chance - even who gets appointed to the student council. Although Chihiro has drawn the winning ticket, this is no ordinary honor. Each day the student-council members must risk their lives to save the school from various forces of evil.