Kareshi Kanojo no Jijou aka KareKano aka His and Her Circumstances.
A bit older and licenced I believe, but very good. Finishes a bit weak though since at the ending of the series the manga had not finished yet. Stupid Gainax go back and cover the rest of the manga!
Second Koi Kaze for a "serious" romance anime. However, the relationship between the protagonists is VERY taboo. Many people cannot watch this series for that reason, but if you just evaluate the show on merit alone it is very well done.