Natsuki Orsiko
Natsuki Orsiko was a supposed "manga-ka" (manga artist) who, according to her deviantART profile, lived on a chicken farm in Japan. However, her "art" was actually images from various HCG games, with a "pencil drawn" effect applied, most likely with Photoshop. The images that weren't from HCG games were pathetically bad MSPaint jobs - her reason for the quality being so bad was that they were drawn "really quickly". /b/, being the patriotic art fans that they are, exposed her as a fraud by compiling a large amount of evidence and comparing her "drawings" to the original CG images from the game companies' sites. This was promptly posted on her DA account, which was deleted, as well as her second account, apparently created after the first one was deleted.
It also turned out she didn't live in Japan, and was most certainly not Japanese. Orsiko isn't actually a Japanese word, for one.
Since then, Anonymous has helped to expose a few similar "artists" on DA, due to it's vast collective knowledge of almost every HCG game in existence.