Takeshi Nanase is an ordinary high school boy who has a somewhat dark past. However, one day, he comes across a girl named Mui Aiba, in a uniform he has never seen before, collapsed on the school campus. This encounters changes Takeshi's destiny completely. Mui tells Takeshi that she is a magician, and she apologizes, for she turned Takeshi into a magician, too. What Takeshi once knew as one world is actually two — the world where magicians live and the world where humans live.