D.C.: Da Capo, Koi Kaze Recommendations
Both dealing with an incest theme (Da Capo to a lesser extent). They're both cute, and serious at times (Although Koi Kaze is almost always very serious).
It's hard to explain, but I highly recommend Da Capo to anyone who liked Koi Kaze. As for Da Capo fans, Koi Kaze is [i]true[/i] incest (you know what I mean if you watched Da Capo), but if you think you can handle Koi Kaze, definetly give it a shot.