Missing Piece

A high school student named Ai experiences a recurring dream of being rescued as a child by a boy who vowed to protect her, though she has no memory of this past. The situation becomes more confusing when a classmate named Tohru Akizuki appears to everyone except her. Curious about him, Ai investigates and discovers that the school has no record of his existence. After questioning him, Tohru reveals he is an ESPer who has secretly entered the school to look into a series of drug-related deaths. Ai becomes involved in his investigation, leading her into a series of dangerous events.