Nanase Takeshi is an ordinary high school student with a somewhat traumatic past. While one might describe him as diligent, the truth is that he is deeply concerned with others' opinions of him. For reasons unknown, he is dating his childhood friend, Isoshima Kurumi, but apart from that, he is a fairly typical guy. One day, however, he encounters a girl in a uniform he has never seen before, who has collapsed on his school grounds. She is Aiba Mui, and her arrival triggers a series of strange incidents. She once stated, "to be honest, I'm a magic user and sorry... I turned you into one too."