Sumika lives with her remarried husband, his son, and her biological son—a family of four. Despite both being divorced once before, they could have been happy, if not for one underlying "issue." However, when her husband begins living apart for work, that problem escalates, threatening the family's stability. Faced with this crisis, Sumika makes a decision that drastically alters their future. Influenced by this incident, the two sons grow closer, forming a deeper bond as true brothers.