Genres: comedy, romance
Themes: Ecchi, Incest
Age rating: Mature (May contain sex, drugs, and extreme graphic violence)
Plot Summary: Keita has two older step-sisters, Ako and Riko, but since they aren't related by blood, they love him in a lustful way. After a mishap at school, Ako and Riko finally confess their love to him. Keita dislikes the thought of seeing them other then brother and sister, but as he tries to enter the same school as his sisters, he slowly becomes attracted to them. Kiss x Sis, a new anime announced over the weekend, based on a manga about sisterly love. And not just any kind of sisterly love, but a double step-sisterly love! That might sound a bit like Onegai Twins, but judging by the manga alone, the Kiss x Sis anime should be a lot more ecchi. Hopefully, anyway.
*Good to know:
The original "romantic incest comedy" manga series, authored by Bow Ditama (Mahoromatic), is still ongoing, and so far it's been compiled into 2 volumes. As Zepy puts it, Kiss x Sis is "one of those manga that lies in the border between eromanga and normal manga". And you can certainly see why, if you take a look over the first chapter, available for online viewing.
KissxSis Manga -> http://www.megaupload.com/?d=5YH9X5DW
>> We're still waiting for any kind of details about the Kiss x Sis anime. !!!