Soulful K.K.
From Nookipedia, the Animal Crossing wiki
"Soulful K.K." (けけゴスペル, K.K. Gospel) is a K.K. song. It plays a soulful piano with another instrument giving it almost a blues feel or someone wondering about life. 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.