After their request to form an occult club is denied by the arrogant student council president Kozono Nami, a group of students discovers an ancient magic book brought by a new transfer student, Kitami Reika. When a spell to induce public nudity works with shocking success, the group realizes the grimoire's power is real, triggering a chain of erotic and supernatural events that begin to unravel the lives of the students.
The Rose Cross club utilizes an ancient magic book to manipulate others and prepare for a dark ritual to summon the Devil on Walpurgis Night. After betraying and sacrificing the innocent Kitami Reika to fuel the ceremony, the group manages to open the Gate of Orkus. As the ritual reaches its bloody climax, a demonic entity emerges, offering a sinister contract to those desperate to survive.