Sun Feng is a junior high school classmate of Li Xiaohong. He has always had a crush on Li Xiaohong. But because Sun Feng is a timid, cowardly and honest boy in the class, he has never been appreciated and favored by Li Xiaohong.

Once, hooligans came to the school to outflank Li Xiaohong, and Sun Feng stepped forward in desperation. He summoned up great courage to help Li Xiaohong scare away the hooligans, but he still dared not confront them head-on. On the one hand, he is a girl he likes, and on the other hand, he is a rogue who wants to get back at the girl. In desperation, Sun Feng had to shoot the bricks in his hand at himself.

In the classroom, Li Xiaohong bandaged the wound for Sun Feng who helped him. In his speech, Sun Feng confided his heart to Li Xiaohong, and was favored by Li Xiaohong. From then on, the two had an ambiguous and subtle feeling.

After communication, Sun Feng learned that Li Xiaohong loved butterflies, so he went to Xiangshan alone on a weekend, trying to catch some beautiful butterflies to surprise Li Xiaohong. Unexpectedly, he lost his virginity and died after being rescued.

When Li Xiaohong learned of Sun Feng's death, she was heartbroken and couldn't control herself, which left an indelible mark on her heart. That mark is like a dead butterfly, beautiful but regrettable. It existed in Li Xiaohong's heart for a long time, until she met a young biologist, and her fate seemed to begin to thaw like a river in early spring. ......