I'm completely sure that it isn't ishikei(he was focusing mainly in Angel Beats! as far as I know), but his very good imitation. Anyway, for these who know how to access exhentai (if you see a sad panda, you don't know the trick ) the translated version : http://exhentai.org/g/282367/1e2d969b86/
I love it when artists use english characters.
I guess using English makes everything looking more smarter and more sophisticated ;O.
Now, I have only to track down the artist's name...