After working it out with some friends on Google+, we found the original doujin this picture was in on e-hentai: http://g.e-hentai.org/g/411332/e023ea74f0/?p=1 The artist is 單気筒, read Tankitou(?), and I believe they are part of the circle Black Rabbits (http://blackrabbits.blog.shinobi.jp/). Heres the japanese wiki on the artist: http://ja.wikipedia.org/wiki/單気筒 If someone can confirm this (because I'm not to sure of myself) and add everything needed to the tags (because i don.t know how).
The book this is from showed up translated on torrents a few days ago. I think the actual story art is by a different artist, but it's still really good. File name is: (C79) [Kacchuu Musume] Sweet Buns! 2 (K-ON!) [English] [Yuri-ism]
I can die now. I mean really this is so wonderful. It might just be my AC on, but the atmosphere here feels a little chilly. Just look, she's got rosy cheeks! I think it's safe to say she isn't horny in the slightest like that. That said, she's exhaling and it almost kind of looks like you can see her breath. I know that's just a problem with the scan though.