#040 of Atomic Bunko/Atomic Pocketnovels. It is said to be a rework of previously stuff posted on the author's website (I can't confirm this tho), so it might be familiar to some readers.
This is not my scan, everything is neat except the cropping. (Usually I don't tend to crop too much in order not to cut off contents from the very edge, however, this will of course leave some black spots.)
info on mugi: http://doujinshi.mugimugi.org/book/569376/
digital ver: http://www.dlsite.com/books/work/=/product_id/BJ013633.html/