Character Arc
Yu Mi-ji is one of the identical twin sisters at the heart of Our Unwritten Seoul. Once a promising sprinter, she was forced to step away from competitive athletics after an injury and now lives a free-spirited, unhurried life in the rural hometown of Duson-ri, helping care for the family without a firm plan for her future. Warm, instinctive, and outwardly easygoing, she carries quiet disappointment over the path that was taken from her.
When the sisters agree to secretly swap lives, Mi-ji steps into her twin's demanding corporate job and the relentless pace of Seoul. Pretending to be Mi-rae, she confronts pressures, expectations, and slights that her sister had long absorbed in silence, and she begins to grasp how much striving and self-denial her twin's seemingly enviable city life actually required.
Over the course of the series, the swap becomes a path to self-discovery. Mi-ji learns to value her own resilience and to redefine success on her own terms, while the experience deepens her empathy for her sister and reshapes the bond between them. Park Bo-young plays Mi-ji as the more openhearted of the two sisters.