Lin Xiao is a top-performing student in his class. After a mock exam, he sees Xu Niannian, who scored at the bottom, hiding in the hallway wiping away tears, and casually tells her not to give up and that they will see each other at Jiangcheng University. He thinks it is just a casual comfort and forgets about it after saying it. However, what he does not know is that this casual remark is written into Xu Niannian's diary, kept in the heart of a girl passing by, and taken as a goal by someone else who silently cares about him. Three years later at school enrollment, Lin Xiao discovers that every casual word he said has been taken completely seriously by all of them.