Ooooo, neat! I was wondering if she was based off of anything. A lot of the Ten Desires cast felt kinda wierd to me because it didn't seem like their physical appearance were based off of much (unlike most Touhou characters), though I figured most of them probably had an inspiration SOMEWHERE that I just didn't know about. This seems to be the one for Seiga here.
A lot (maybe not all, of course) of the differences look like they can be chalked up to the perspective.