Because there is a sentence in the poem, which was given to Yan by Yan's girlfriend before her death, and Xu Dunhe, the boyfriend of Ruijing, the girlfriend of the school beauty, also found this poem, which he thought was related to her death. By chance, Xu Dunhe met Park Canhong, a bully on campus. Xu Dunhe saved him and made a "friendship contract" with that man. The two agreed that Xu Dunhe was responsible for protecting the man from bullying, and the man mainly helped Xu Dunhe find the truth about the death of his girlfriend Ruijing and catch the real murderer.
The ending of the play is very perfect. They found out the cause of Ruijing's indirect suicide and the murderer who caused her suicide. In fact, he is usually the most cowardly person. The man told him that in every friendship, everyone will have their own difficulties, everyone will be vulnerable and need encouragement and comfort. Everyone has their own worries and anxieties, as well as their own misfortunes in friendship. So each of them got his own happiness. The male examiner was admitted to his favorite university. Yan bravely told her parents about her favorite major, and Xu Dunhe also let go of her ex-girlfriend Rui Jing.