Satomi Mao is Tetsu Harisugawa's childhood and first guy friend. This was due to the accident that happened to both of them during their childhood, where Harisugawa saved her and instead got hit by the car that was supposed to hit Mao. The same incident happened after several years though Mao was saved, Harisugawa was sucked into a mirror, which Mao bought at a store near the incident happened. This made Mao thought of taking responsibility of Harisugawa.