A story about the joys and sorrows of the young generation born in the 1990's. It follows four people who have a secret that they keep. Because of an incident when she was in high school, Luo Xi transformed into a submissive and weak person when she entered university. Li Xin discovers that Luo Xi was the hero who saved him in the past, so he sets out to help her regain the part of her that she lost. Their youth is filled with embarrassing moments, but in each of their hearts is a secret. When it comes to family, friendship and love, what choice will they make?