Fairly sure this is a nude_filter, as there doesn't seem to be any official source. There is an official clothed ver. though.
Edit: Looks like it is, there was multiple versions posted on yande.re. The original thread it was posted seems to confirm that aswell (At least from what google translate is giving me)

Looks like you're right. Flagged it.

I'm guessing the original is out there somewhere, as konachan has a cropped wallpaper ver. of the image.

It seems like there is an ero artbook coming out tomorrow that may contain this. The preview pictures only seem to show the clothed version though.

Considering the quality looking awfully like a digital image rather than a scan, makes me wonder if the author/jumpsquare posted this.
Would be great if someone could actually to a quick translate of the posters posts in the original thread to confirm. Google translate only does so much :x
Edit: More preview images. Still not showing this image though..

DakuTree said:
ero artbook coming out

o_o Holy shit what a surprise.

It's a shopped version of an image that was first used on a poster and subsequently included in the new artbook.