Akatsuki Ousawa was pulled into the fantasy world of Alayzard, where he defeated the Demon King and earned a name as the Rogue Hero for his independent, womanizing ways. He then chooses to return to Earth, a world where people have been crossing into other realms for thirty years and the few who come back keep their powers. Akatsuki does not return alone: he brings Miu, the defeated Demon King's daughter, and passes her off as his little sister to hide who she really is. The pair enroll at Babel, a school meant to train returnees to use their abilities for humanity's benefit, though its real aims are unclear. There they face a hostile, powerful student council, while trouble from Alayzard's defeated Dark Cult is far from settled. The action fantasy leans heavily on ecchi content.