Also, just looking at pictures of her in the past shows that her love of huge lips is nothing new.
If I may:
2006:
http://www.greatful-days.net/reflect...p?image_id=989
Infamous A-BEST 2 from 2007:
http://www.greatful-days.net/reflect...?image_id=2030
GUILTY cover, 2008:
http://stylejapan.files.wordpress.co.../12/guilty.jpg
Undated, but it's nothing recent for sure
http://7hotasiangirls.com/d/34973-2/...llery+_21_.jpg
So those are just a few things I found in like 5 minutes. I really think that either a) it's just something she's always gone in and out of being into, or b) her lips are naturally bigger and her makeup artists want to show them off.
I don't really think this is collagen because her lips don't ALWAYS look like that. Just sayin'.