From Nookipedia, the Animal Crossing wiki
Kazumi Totaka (戸高 一生, Totaka Kazumi), born August 23, 1967, is a video game composer. He composed various songs from Nintendo games, including "Totaka's Song". He is also the voice of K.K. Slider. In fact, K.K.'s Japanese name is based off Totaka's name. In Japan, last names are pronounced first, so it would sound like Totaka Kazumi. If his name is abbreviated in Japanese, it is Totaka K., similar to Totakeke, K.K.'s Japanese name.
Kazumi Totaka is also known for voicing Yoshi in the Mario series, which he has done since the game Yoshi's Story in 1997. When he is a composer for Nintendo games, he often secretes "Totaka's Song" within them. He put "Totaka's Song" in all of the Animal Crossing series games under the song title "K.K. Song," which is a secret song that can be obtained only by asking K.K. Slider.