Anyone know what series this image belongs to? Could be anime, manga, or even a visual novel, I'm not sure.
The original uncropped image is from Dorei Kishi 1 「奴隷騎士Ⅰ」, a Fate/stay night hentai manga by the doujinshi circle KUSARI. On a prior page is printed


  陵辱連鎖シリーズ＋オリジナルイラスト集


which translates to:


  Ryoujoku Rensa Series + Original Illustration Collection


Ryoujoku Rensa is another hentai manga by KUSARI, based on the 2005 eroge novel of the same title. It is clear that the image is an original illustration.