The Ghost of Curses Past.

This is a strong story taking the theme that, when Happosai split Ranma into male and female parts, the female part lived rather than was destroyed as in the episode.

In this story the female part, Ranko, was basically abandoned by everyone else. People were ultra-excited about Ranma being male permanently and most of the people mistreated Ranko. Finally, Ranko had enough and left to live on her own.

Ranma, though, is seriously injured by Kuno (who is arrested, finally), and Akane tells Ranko that Ranma is in need of a kidney transplant and she is the best choice Ranma has. She refuses and throws Akane out.

Later, it's revealed that Ranko did volunteer to donate a kidney, and when Akane finds out she insists that Ranko come back to live with them. Nodoka is willing to adopt her as a daughter, but there's still the problem that Ranko still has Ranma's feelings for Akane.

It's a problem solved when Akane uses the same device to split herself into male and female parts, allowing Ranko to be with a male-type Akane, and Ranma to be with the girl-type Akane.

I think it's a good story. I actually disliked the episode in which Ranma's female half was split off; it made it appear that she was totally evil rather than just his female persona. This story also makes sense in the way that the family behaved towards Ranma and were not nice towards Ranko. Kasumi's basically the only really sensitive person in the entire group.

I also like the way Nodoka really loves Ranko and adopts her, finally bringing the girl the happiness she deserves.