Justine Waddell does her first nude scenes in Mishen (2011) a Russian movie. Justine has about five minutes of intense sex/nude scenes mostly showing her butt. For much of the nude scenes she covers her breasts with her hands and her face is obscured. However we fleetingly see her face and body in several scenes including two full frontal scenes, which suggest all the nudity is done by her.
Clips at some of the usual sources.