Jian Jian once thought that only those who were good enough to build a hard shell could not be hurt, but for the warmth provided by poor student Li Muyu, she maintained a dangerous relationship with him. In the self-righteous promise that they will never separate, Yu Qian and Yu Yu, a pair of brothers and sisters, quietly integrated into their lives. Is "birds of a feather flock together and people divide into groups" the law that governs this world? Are the promises made in the past still true? At the same time, the simple and harsh family environment has turned around with the appearance of another mysterious woman. What impact has she brought to the simple life? Can I continue to stick to the absolute that I believed in when I was young?