Otome wa Boku ni Koishiteru doujin(Behind Moon - The Maiden Raping My Sister). Halfway through Mizuho and Takako seem to have had their genders reversed. Is this /d/?
Nevermind lol.
http://rapidshare.com/files/45739095/The_Maiden_Raping_My_Sister.rar
I wish this was translated.