In senior high, they missed each other because of a misunderstanding and after graduating, they return to their alma mater as teachers. The male lead can't recognize the female lead because seven years have passed!? An insensitive cold female PE teacher, and a two-faced smiley male math teacher, meeting once again. Things remaining the same but people changing, can the feelings that once died come back again? Meanwhile, the secret from senior high is slowly revealing itself...