Notes:

dA source
Naver source

The artist notes that this was done 3 to 4 weeks prior, but did not post until now because it may be too explicit, what's with being New Year's and all that. Maybe he/she felt it was too soon to post such dark image (the artist have been posting some dark images in recent posts in his Naver blog).

Also, Naver source has not-in-camcoder mode, if you dare.