"Lee Sunwoo is a prominent character in the Japanese manga ""Onsaemiro."" He appears throughout the series and plays a critical role.

At the start of the story, Lee Sunwoo is introduced as a talented pianist. He is the son of a wealthy family and is well-regarded by his peers in the music industry. However, Lee Sunwoo is also known for his cold and aloof demeanor, which makes it difficult for others to get close to him.

Despite his success as a pianist, Lee Sunwoo harbors a deep-seated anger and resentment towards his parents. They pressured him into pursuing music, despite his desire to pursue a different career path. As a result, Lee Sunwoo feels trapped and is searching for a way out.

Fortunately, he soon finds an unlikely ally in the form of the main character, Kim Yoora. She is a skilled singer who is also struggling to find her place in the world. Together, the two of them form a bond and work to support each other through their struggles.

As Lee Sunwoo spends more time with Yoora, he begins to open himself up and reveal more of his personality. He is revealed to be a caring and compassionate person, willing to put others' needs before his own. This helps him to form close relationships with other characters in the story, despite his initial reservations.

Over time, Lee Sunwoo's talent and hard work pay off, and he becomes a successful composer in addition to his work as a pianist. He also reconciles with his parents and starts to forge a new path for himself.

Overall, Lee Sunwoo is a complex and fascinating character in ""Onsaemiro."" His journey from a cold and guarded pianist to a compassionate and successful composer is one of the highlights of the story, and his struggles and triumphs are sure to resonate with readers."