Well, actually, to be more specific, Sega only let people adjust the breast size in Virtual-On Force if they pre-ordered the game.
Read all about it here:
http://www.examiner.com/video-game-babes-in-los-angeles/sega-allows-gamers-to-adjust-the-bust-sizes-of-female-characters --- I made a website where you can watch a live video feed of me playing video games. That might sound weird, but it's actually a lot of fun! evaxephon.com/stream