Jun is an aspiring teacher who has non-blood-related twin imoutos, Koruri and Chidori. One day their mother and older sister tell him that they are actually succubi. Succubi require a man’s essence to become adults and they wish that that he will help Koruri and Chidori become adults. He gets help from chibi teacher Tsubame to enter the girls-only boarding school that they are attending. For his precious imoutos, he will do anything...