From Nookipedia, the Animal Crossing wiki
Spring Blossoms is a K.K. Slider song. It first appeared in Animal Crossing: Wild World if the player put an invalid song name. The song reappeared as a secret song in Animal Crossing: City Folk. When the player puts in the song's name, K.K. Slider will talk about a character named June. The music is originally from Cherry Blossoms Festival theme from Dōbutsu no Mori and Dōbutsu no Mori +. None of the villagers have this song.