The 16-year-old heroine Li Duan was in her first year of high school when she met Chen Chen who had traveled from the future. Chen Chen has the power of any door. He just wants to go back to the past and protect Li Duanzheng. He wants to make up for the guilt he feels towards Li Duanzheng. In three years, Chen Chen became a mathematics teacher and stayed with Li Duanzheng. A very interesting story happened. Because of Chen Chen's three years of protection, Li Duanzheng's life changed. The hateful head teacher Wang Ke caused great harm to Duan Zheng, but with Chen Chen's protection, she had the best high school youth life. This may not be a story with a perfect ending, but I will do my best to meet Chen Chen's expectations.
Intention: Give us a chance to protect someone, even if we have no results, even if I disappear, I just want to protect you.