Rengoku no Karutagura

Mysterious demonic ceremonies at Seirei Academy make transfer student Yuriya Yuuki a target of suspicion among his classmates. One evening, he spots a girl wandering outside his dormitory window and follows her into the night. There, Yuriya comes across a book that lets him summon the demon Belial. Belial invites him to make a contract, drawing Yuriya into the mystery surrounding the ceremonies.