Yan Tang has secretly loved her next-door neighbor, Jiang Baiyu, for many years. Because of their childhood engagement and their families' arrangements, the two begin living together. As they grow closer, Yan Tang gradually realizes that Jiang Baiyu does not see her as merely a little sister. Jiang Baiyu, meanwhile, moves from restrained affection and quiet care to openly expressing his love. After overcoming misunderstandings and outside conflicts, and uncovering the truth from nine years ago, the two finally confirm that their love has been mutual all along and get married.