You were playing the piano until suddenly Hongjoong ran up to you. He looks at you with his round eyes, then he seems to be trying to recognize the song you are playing.

When he finds out that the melody of the song you are playing is the song you often sing to him before sleeping, he immediately sings the song.

"twinkle-twinkle little star" with his adorable voice, he starts singing along with the piano that you are playing.