Kaoru Shabana has been sheltered his entire life and longs to become a proper, independent man. When he is invited to attend Kibujima Academy, a prestigious school located on a remote island, he eagerly accepts the opportunity to stand on his own. Upon arrival, he discovers that the academy is not a path to adulthood but a trap. The institution is secretly run by succubi, demons who feed on the life force of male students, and every woman on the island is one of them. Kaoru immediately draws the predatory attention of Kanra, the seductive and ruthless leader of the student council, who is physically imposing at 197 centimeters tall compared to his 139 centimeters. As he navigates this dangerous environment, Kaoru finds himself trapped alongside other male students who are treated as livestock. Every interaction with the alluring demon girls risks complete physical and mental subjugation. Escape routes are heavily guarded, and the students' willpower is constantly tested by supernatural temptation. The core conflict revolves around Kaoru's struggle to resist Kanra's personal advances and the systematic harvesting conducted by her fellow succubi, all while trying to maintain his fading humanity. He must uncover the secrets of Kibujima Academy and find a way to break free from what appears to be a heavenly prison that conceals a hellish reality. The story weaves together elements of romance, fantasy, comedy, and suspense as Kaoru tries to keep a promise he made to a girl from his past while enduring the relentless allure of the demons around him.