Main •
Song Kang as Kang Bi-o : A man who is regarded as a potential competitor for the top three piano competitions globally, having continually achieved first place in both academic pursuits and piano proficiency. •
Lee Jun-young as Choi Jeong-yo : Born into a tough family, he neglected his talents. But when he arrives at Korea Arts High School, he runs into the piano genius he was once totally into. •
Jang Gyu-ri as Hong Jae-in : A viola major who possesses a keen musical sensibility and an exceptional ability to recognize melodies. However, her pursuit of music that resonates with her is an ongoing challenge.
Supporting •
Kim Joo-hun as Do Hyeon-soo •
Yoon Se-ah as Kang Ji-hye •
Jung Jin-young as Kang Seung-woon, Bi-o's grandfather ==Production==