K.K. Faire
From Nookipedia, the Animal Crossing wiki
"K.K. Faire" (ハイサイけけ, Hello K.K.) is a K.K. Slider song that is old-fashioned, traditional, and sounds much like traditional folk music from Okinawa and the Ryukyu Islands of Japan. The instruments appear to be mainly traditional Ryukyuan instruments, such as the Sanshin (banjo-like instrument), as well as the voice of an elderly man singing lead (K.K. Slider's vocal parts), with occasional cheerful chants (the high wind instrument) that are often heard in traditional-style dances at festivals. Cheri and Truffles can be seen on the cover. Antonio, Rasher, Cyrano, Chico, Fang (in Animal Crossing), Rory, Shinabiru, and Violet play this song on the stereo in their homes.