Busujima Tanehisa, a human possessing extraordinary vitality, is recruited by the succubus Lima Grimalkin to serve as an instructor for "failed" succubi who have never experienced human semen. Armed with a magical bell that forces obedience, Tanehisa begins the re-education of the proud and stubborn Iko Baikon. Despite her initial resistance, Iko is quickly overwhelmed by pleasure, beginning her transformation into a craving pervert under Tanehisa's intense guidance.