That song is just so out of place with the rest of the soundtrack, that I figured it must have a story. Most of the special event music that is horrifically out of place came from other games. (Like Chu Chu Rocket, Samba De Amigo, Nights, etc.) The whole thing with this is bizarre, especially since the disk to even hear the song is completely unobtainable (yet bundled with blue burst).
Since I have several partial answers, I'm thinking of giving two partial prizes. One to srojasq for trying everywhere and one to gore_u for the confirmation of the music contest. However, it hasn't even been 24 hours since I posted this. If I haven't gotten any more responses by Wednesday, I'll just give out prizes to you two.