After a life-threatening accident leaves him critically wounded outside the hospital doors, Sora receives lifesaving aid from nurse Yagami Yuu. In the emergency ward, he encounters the facility's director, Mikage Reika, who extends an offer for him to serve as a test subject for new procedures. Lacking any family connections, Sora accepts the proposal, placing his recovery in Yuu's capable hands and setting his destiny on an unforeseen path.