YES first time since 2008!
I'm guessing acoustic "Song 4 U" or a track from "again". (Possibly a song from the third release IF it's a mini album)
Possibly coupled with an old hit since it's a) her 15th anniversary b) she did that in 2008 c) she needs to gain casual fans back with the recent scandal
Hoping she won't sing "how beautiful you are", that's no use right now
EDIT: Omg Nana Mizuki is performing, too! First the summer festival, now the regular FNS. Proud of her
She's finally getting on normal TV shows, she used to ONLY perform on Music Japan, now she got Kouhaku and FNS.