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. Chihiro's luck is about to be put to the test yet again, and one wrong move could mean death!
(Source: Manga)