If you look, she's putting a lot of her weight on her back against the wall at the moment. And since it's after sex, won't be much bow chika bow wow left for a while.
Awesome pic. Be sure to play the actual game, available in English at http://www.jlist.com/s/p014 . Story by the creator of Kana Little Sister, art by the illustrator of the Certain Magical Indes novels. Yes, it's awesome.