This is also a Doujinshi released on Comiket 75 Big Sight Tokyo December last year. The artist or illustrator, Tsubasu Izumi (和泉つばす, Circle name: Hisuitei, 翡翠亭) is one of my favorite one who has done lots of works, say, Akane-Iro ni Somaru Saka. Most of her (his?) works are outstanding and you may want to drop by the blog.