
The reason I am focusing more on
NA・GA・RA is because that was the first song performed by Idoling members at TIF. What took me a bit to figure out though, is WHO sang it. Two of the original members of GizaGiza Idoling graduated- Koizumi Rumi (Jan 2009) and Michelle Miki (Mar 2009) -cutting their numbers down by half. So at first I thought maybe the company simply added girls to fill in their place, meaning that Fonchi and Miyake would have still performed.
I felt really lame when I figured it out, because it was glaringly obvious. If you look at the image up there (a screenshot of the video playing on my computer, cause,
oh yes, I have it downloaded), in the lower right hand corner above the song's title on the blue/yellow strip it says
'フリフリアイドリング!!!' So it ended up being Furi (フリフリ) performing Giza (ギザギザ) 's song at TIF.