The canonical genderswapped version of Saotome Ranma. In the series Ranma 1/2, Ranma is cursed 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).