The middle-aged teacher with a strong sexual appetite, Busujima Tanehisa, is ensnared by a succubus from another world named Lima Grimalkin. While immobilized by a spell, Lima starts to masturbate him, and due to his overabundance of sexual desire, she assigns him the task of re-educating succubi who have failed their exams. He is introduced to two failing succubi, Iko Bicorn and Ruku Orcus, who initially display a rebellious attitude but are subdued using mysterious tools. And so begins the re-education through orgasms of the arrogant, dark-haired succubus, Iko!