User blog comment:IamJakuhoRaikoben/Sorcerer Magazine, Issue 21: September 2013/@comment-4449950-20131006091718/@comment-4449950-20131006094248

I'm scared that if I give you a hint it'll become waaaay too obvious =/ But then again, as I said it just hits me in the face every time now...

But fine, here's a clue:

When I first saw the image I thought somebody in the Image Guild had stuffed up.

There you go ^__^ Alas, to double check I re-watched the ep and it's there too, so it's not the IG, rather the actual animators.