There are several reasons affecting/helping NANA's sales:
1) the hardcore NANA manga fans (trust me it's huge in Japan)
2) it's "NANA" singing it...
3) one member of GLAY composed the song
4) the author of NANA wrote the lyrics
If ayu can get 160K at least on the first week (like BLUE BIRD), then ayu will have more chance to get no. 1. If the sale sucks (like Startin'/BTB), I think NANA may get no. 1..
so why take the risk? I'm sure there should be other safer release dates other than NANA/REIRA weeks..
Btw... GLAMOROUS SKY's second week was like 90K.. so probly this time she may manage to get over 160K copies on the first week...
