The canonical genderswapped version of Saotome Ranma. In the series Ranma 1/2, Ranma is cursed so that whenever he gets soaked with cold water he transforms into a girl. He's able to revert back to a man when soaked with hot water.
In terms of appearance, she very closely resembles Ranma's male form, but has red hair as opposed to black hair, is about a head height shorter, and of course has female primary and secondary characteristics (breasts, body shape, etc).
In situations where she appears alongside her original male self, the dual persona tag should be used.