Zheng Qingyan never expected that Jiang Yan, her online first love whom she broke up with two years ago due to lying about her age and blocked in a fit of anger, would turn out to be the substitute teaching senior for her university Foreign Literature History course. One is a freshman class monitor, and the other is a graduate student under a professor, and official business forces the two to grow close again. She thought he already had a girlfriend, but he stayed by her bedside when she was sick; she thought that relationship had long been let go, but he held her hand in the blackout corridor and proposed making up. Until they fell in love again, she gradually learned that he had wanted to wait for her to graduate back then, but the promise failed to be delivered. The first love missed by two years finally continued to write its answer in this reunion.