the anime revolves around high school boy Ryōta Murakami, who cannot forget his female childhood friend whom he let die in an accident. Feeling that he must fulfill their promise of proving the existence of aliens, he has continuously looked up at the starry sky as a member of the astronomy club. One day, a girl named Kuroha Neko who looks exactly like his childhood friend appears as a transfer student. She displays supernatural strength when saving Ryōta from a foreseen accident. It turns out that Kuroha is a magic-user that has run away from an alien research lab. From then on Ryōta supports these magic-users, hoping to live normal lives regardless of being pursued. How will Ryōta's life change now?

the director of this anime is the same as elfen lied