ung Da Jeong and Hong Dae Yeong have been married for almost two decades, raising their twins together. Despite appearances, their life is far from ideal, filled with Dae Yeong's incessant nonsense. When he gets fired, and Da Jeong can't take it anymore, she files for divorce. This drastic step forces Dae Yeong to reflect on his life and all his regrets. Suddenly, he transforms into an eighteen-year-old with the same middle-aged mind. Renaming himself Ko U Yeong, he enrolls in his children's school, gaining a new perspective on life.