Story (3/5) : I'm not to strict by giving it 3/5, the plot is in the description but the show doesn't follow the plot or is not developed. Instead they throw us random fillers + the female lead is the typical tsundere (violence for no reason, refuses to admit feeling, jealousy, have absolutely no skills and reason to be liked by the male character). The main lead, for some reason, gets exited when seeing his sister in sexy clothing. The worst is that the other characters are acting accordingly : they try to separate the brother and the sister when they could get in "hot situation". I don't mind this kind of comedy, but for crying out loud their suppose to be siblings, instead of doing comedy effect with this, they should add dramatic romance instead. It just doesn't feel realistic.
Dialogue (2/5) : It's craps
Animation (3/5) : It's very average for a 2008 anime
Entertainment (2/5) : First two episodes, you are exited to see what'll happen next, later on it's filled with boring parts and stupid classic fillers.