I don't think it's ever been confirmed who the artist is, but it's most likely Fujisaka Kimihiko, who's responsible for the majority of Drakengard artworks, and who was in charge of the designs for 3 afaik.
Also, why is it flipped.

IronSavior said:

Also, why is it flipped.

While I don't know for sure, I'm guessing it's to bypass duplicate check as most of the uploader's posts were dupes.