Thanks to the Ranma 1/2 FAQ for info on the last name!

KonatsuName: Kenzan Kontasu

Curse? Nope.

First Appearance: Manga Volume 35

History: Konatsu is really a boy raised mistreated, as a kunoichi (female ninja). Much like Cinderella, Konatsu has a horrid stepmother and stepsisters (which are very ugly) that he later leaves happily to work for Kuonji Ukyou, earning probably less than minimum wage. As he works for Ukyou, he is also in love with Ukyou, her being (I suppose) some sort of saviour from his mistreatment. Konatsu is cute, being very happy with very little in life thanks to his upbringing. So, in a way, Konatsu is like Sasuke, but a lot less irritating (At the end of volume 36, Ukyou tells Konatsu that they will be stuck eating bread with rice for a week, and he comments on how it is such a luxiorious meal ^_^).

More Konatsu on the Web:

The Ranma 1/2 Gallery's Page about Konatsu (more stats)

Click here for a summary of Konatsu's first appearance (Thanks to Joshua M. Cole for the translation).

Here is another summary of manga volume 36, part 11, thanks to Michael Wong and Xavier Hardy