The plot starts ten years ago when childhood friends Ryouta Murakami and Kuroneko set out to prove the existence of alien life. But a tragedy strikes; there is an accident which gravely injured Ryouta and kills Kuroneko. In memory of his dear friend, Ryouta now searches the night sky every night in the hope that his friend was right about the existence of aliens.
Back to the present, we find that Ryouta is a top student at his school and currently the only member of the schools Astronomy Club. Everything he believes in gets challenged one day when a new transfer student joins his class, a girl named Neko Kuroha. She is a dead ringer for his old friend Kuroneko, and even her name sounds similar and there is something strange about her… She has superhuman strength and predicts death. He becomes entwined in a world of magic and witchery; his life will change in a new direction forever.