"Let me be the moon that keeps you safe, Sarang." Saebi was always an example, an independent person. Despite the circumstances she lived in, divorced parents, an abusive father, and a mother with her own priorities, nothing stopped her from educating and taking on the role of mother to Sarang, her younger sister. Sarang cannot live without Saebi's support. With an angelic face, advanced intelligence and a soul blessed with a gentleness that cannot be found in anyone else, she was always loved by those around her. The two sisters live for each other, until one cold January night, when fate exposes Sarang to the hardships of life, living for both of them.