Missing Piece

High school girl Ai had a strange dream about a childhood past in which she was rescued by a little boy who promised to protect her. The dream seems like a fragment of her memory but she does not have any recollection of the past. Things start to get stranger when there is a guy in her class whom she does not recognize at all. It seems that everyone in the class knows about Akizuki Tooru except for her. Sensing something strange about Tohru, Ai went to conduct an investigation on him and found t...