I was randomly surfing through some ljs once again and I found this piece of treasure waiting to be discovered.
"Rakuen"... This is not the download link as I'm not the owner of the file being shared. It's just the link to the journal posting a download link to the song.
If you care to read the comments posted, it isn't the "Fight Song" they released. It's actually Nino's song that Arashi re-wrote and became "Fight Song"...
I don't know much about the song either but it's another piece of heaven for me. ^_^