If you like perverted ecchi, then this is really top grade stuff. This anime is about a pair of brocon ecchi twin sisters who want to seduce their step brother, and spare no resource for it.
TV Series is ok (a part from a couple boring episodes), but OVA are legendary. If you watch the Karaoke episode, you will never forget it for the rest of your life. Before watching Kiss x Sis, I cannot even imagine perverted stuff like this. Thank you for expanding my horizons.
If instead you're a (boring) god-fearing little sheep, then go away and don't event watch it, because Jesus won't forgive you! :))). Please don't annoy us with useless reviews of stuff you don't understand and are not meant for you to watch, go back to watch superheroes movies and other 7-years old stuff like that. Thank you.