Missing each other due to misunderstanding in high school, the two of them returned to teach at their alma mater after graduating from college. After seven years, Muli Yang didn't recognize that she was the young girl An Xun. Now one of them is a gentle yet scheming male math teacher, and the other is an unromantic and poker-faced female physical education teacher. When they again meet each other, the things are still there, but men are no more the same ones, can they restart their relationship? And the secret of high school is gradually being disclosed...