looks like there's good light work on those photos, i think she herself is taking them and posting them in order to rack up popularity, either that or Vampire coz u know, they can just get there, doesnt explain the light work doe
Selfies seem to be a pretty easy, straightforward theory. The girl in question also didn't seem particularly worried at all about it. Wonder if they'll subvert it.
Seeing as their are no new characters introduced that could be the perpetrator i'm guessing that the girl was doing lewd photos to boost her popularity.