Sora was lying in front of a hospital. He was seriously injured, and when he was about to die, a nurse, Yagami Yu, helped him.
He was sent into an emergency ward, and he met a beautiful woman, Mikage Reika. She was a director of the hospital, and she asked him to become a test subject. Because he didn't have any relatives, he accepted it. Then, Yagami Yu was supposed to take care of him.
Since that day, his fate had changed a lot.

(Source: AnimeNfo)