This one is a spinoff from Kore ga Watashi no Goshujin sama. The story is about a school, Shiritsu Yurihime Gakuen, an all girl school specialized in preparing maid for the otaku moe industry. Of course, the leader is no less, a Nakabayashi, a heavy-class otaku with unlimited asset to burn for while seven generations.
Our main heroine this time is Mochida Natsumi, a girl with hentai mind as worse as Yoshitaka and luck as bad as Izumi. She came with the ambition of building harem of imouto. But life is not as beautiful as in those harem love comedy genre anime/manga, because in this school, all the girls are well educated in otaku business.
Her couple is Kitamura Kiriko, a.k.a Mitsuki 2. Cute, innocent (looks) and demonic personality to the bone and teeth. She's also Natsumi's roommate, imouto, as well as goshujin sama.
Kore de anata wa imouto no dorei to iu nasakenai jyougou wo te ni ireta no yo ♥
(with this, you've got yourself the miserable title as "sister's slave" isn't it ? ♥)