The series is set in the year 2086, ten years after magic is revealed to the world. Tōta Konoe is a young boy who has always dreamed of leaving his home village and find out what lies atop the high tower in the capital. But his teacher and guardian Yukihime claims that it will only be possible once he defeats her, a feat that seems impossible for him. However, once Tōta is mortally wounded by a bounty hunter coming after Yukihime's life, she reveals herself as a vampire and saves his life by transforming him into one of her kind. Thus begins Tōta's adventures in the world of immortal beings in a society where magic and technology are highly advanced to the point of being almost indistinguishable.