judging by the fact that this is the ten desires cast, I think that might be Nue standing next to Kogasa.

It looks more like Yuka without the wings.

I dunno why but Yoshika reminds me of L, lol

Got really surprised about the artist. She was one of the best Touhou drawers in the TegakiE website.

Oh gosh, I couldn't stop myself from adding this to my dA favorites.
This picture is simply epic.