Soulful K.K.
From Nookipedia, the Animal Crossing wiki
Soulful K.K. is a K.K. song. It plays a soulful piano with another instrument giving it almost a blues feel or someone wondering about life. It looks like it is in a church. Its name may get confused with K.K. Soul sometimes. Yuka, Marina, Tipper, Dora, Pierre, Spork and Apollo will play this song if they have a stereo system in their house. Spork and Apollo also appear on the album cover, along with Deirdre, Kitty, and K.K. Slider himself.