The heroine and the hero's parents are good friends, and the hero is the heroine's big brother next door. From the first time she went to the male protagonist's house, the female protagonist felt that she was on a path of no return, and all the feeling of loss was given to him. Compared with her enthusiasm, he only regarded it as the ignorance and impulsiveness of the little sister next door. When she swore to him, "I like you," he would always ruffle her hair and say to her, "You are still young. When you grow up, brother A Xing will be old." But when did it start? When she called him to tell her troubles, he had the idea of protecting her so that she could be carefree...