"Boys are creatures whose sight will follow the girl they like wherever she is. And if there it comes the chance that the boy realizes that the girl is in danger, if he is able to save her they will feel the ultimate bliss in life" is something that Harisugawa Tetsu has pointed out, and true enough he has always been following with his eyes the girl named Satomi Mao.
Thanks to certain details in their childhood, Satomi has always been friendly with Harisugawa and she has a friendly budding relationship, completely unaware of Tetsu's feelings for her. Tetsu for his part preferred to play the friend part and keeps his feelings hidden for the sake of not endangering the closeness that they already have, ever since he was young Tetsu had believed that if he can build little by little a good relationship with Mao, he will get to the point where he can confidently confess to Mao and not get rejected, Tetsu has always been waiting for his one true chance without getting too close to Mao by accident.
At first it seems that this "stalemate" will never be broken; however, one day Mao sees a strange mirror in an thrift store and for some reason she feels that she must have that mirror. Mao buys the mirror without thinking twice about it.... But she is completely unaware that the mirror will change forever Tetsu's life as well as her own.