Male Korean Piano prodigy He dreams about one day impressing his Grandfather with his skill of playing the piano, but gets hit with constant disapproval from his lack of musical sentiment. With his family pressures and high expectations, he becomes deeply immersed into making him proud no matter what. Kang Pio is a strikingly handsome and composed young pianist, with a tall, slender build, neat dark hair, and a naturally elegant presence. His restrained expressions and calm, almost unreadable gaze often make him appear distant, especially when he is concentrating on music. Even when surrounded by other students, Pio carries himself with quiet discipline—as though he is constantly measuring himself against an impossibly high standard. His relationship with Choi Jeong-yo is at the heart of his story. Though they are opposites—Pio is precise and controlled, while Jeong-yo is instinctive and emotionally expressive—their differences bring them closer. Jeong-yo teaches Pio to experience music more freely, while Pio helps Jeong-yo find confidence in his own talent. Their friendship develops into a powerful bond, making their eventual separation especially painful for Pio. To Pio, Jeong-yo is more than a rival—he is the person who understands the part of him hidden beneath his perfectionism.

Kang Ji-hye is Kang Pio’s devoted but demanding mother, who recognized his exceptional piano talent from an early age and dedicated herself to supporting his musical career. She is deeply invested in Pio’s success and, above all, wants him to earn the recognition of her father, the renowned conductor Kang Seung-woon. However, when Choi Jeong-yo enters Pio’s life as both a close friend and a gifted musical rival, Ji-hye becomes increasingly anxious about Pio being surpassed. Her determination to protect Pio’s position—and her insistence that he remain the best—becomes an important source of tension between Pio and Jeong-yo, placing pressure on Pio’s friendships and his own understanding of music.

Female Korean 17 years old A viola major at Korea Arts High School, Hong Jae-in is a bright, warm-hearted young musician with an unusually sensitive ear and perfect pitch. She has the ability to recognize musical notes and performances with remarkable precision, making her especially perceptive when it comes to the emotions hidden inside a piece of music. Unlike students who measure music through rankings and technical perfection, Jae-in searches for something that genuinely moves her. Jae-in carries a naturally cheerful presence. Her expressions are open and lively, and she often brings a softer energy into an environment dominated by intense competition and pressure. Beneath that brightness, however, she is musically discerning and surprisingly perceptive; when she hears something extraordinary, she knows it immediately. She has known Kang Pio since childhood and is one of the people closest to him. Pio's piano playing has fascinated her since they were young, and her extraordinary hearing allows her to recognize his playing almost instinctively. She understands the perfectionism behind his music and becomes one of the few people who can see beyond his polished exterior. When Choi Jeong-yo enters her musical world, Jae-in is immediately captivated by the raw, unconventional quality of his playing. Rather than judging him by his background or status, she responds to what she hears. Her recognition of Jeong-yo's talent helps bring him closer to the school and, eventually, into the complicated orbit shared by herself, Pio, and Jeong-yo.