Joseph, a former nursery school student, and Cheongmyeong, the son of former popular singer Hoseok.
Cheongmyeong and Joseph grew up in different environments, so it's hard to understand each other, but with the common denominator of music,
They become close to each other, and Cheongmyeong, who believed in no one, opens his heart to Joseph.
The song, which he wanted to play to Sun-ah, whom he loved in the past, is also presented to Joseph.
How will the song end?