The plot is straight forward; Ako and Riko help Kieta pass his entrance exam into high school. What you see on the outside is what you get. There isn't anything hidden underneath the story-line, but even so the anime is able to deliver many things along the way; from entertainment to its viewers to splendid characterization of its characters. In every episode, Ako and Riko would do something different to get affections from Keita, and each time the things they do are hilarious while other time they are more perverted thus making the contents border-line hentai. It might be great for fan service, but deals a lengthy blow to the anime in a sense that it provided a scene that did not benefit the story-line, but rather pro-long that specific episode. As I mentioned earlier, some scenes were did not enter the realm of border-line hentai thus it was a great source of comedy and made the anime enjoyable. On there other hand, characterization was good since the anime was able to individualize each character in their own specific group thus each character had their own specific feature, so if someone ask me to recall a character on their trait---doing it would be an easy task.
In terms of art, the anime is ranked average due to the fact that it can be found in most harem anime, but there were moments in the anime when the art shown improvement such as in the "ecchi" moments. The art for Ako and Riko is fascinating; the way they look is appealing and make them stand out from the rest of the other characters thus they added a kind of uniqueness to the anime. The opening song was fine, but th ending song is a different story. The ED song was very catchy and easy catches one attention and you can't help it but to listen it to the very end. Along with the ED animation, how can one resist?
In the end, Kiss x Sis is a pleasant anime and for people who enjoy ecchi moments and a good slice of life.
