Why does Ranma change into a girl?

The premise was a solution to a writer’s problem. After two series with female protagonists, Takahashi conceived Ranma ½ as a martial-arts manga that ties every part of everyday life to fighting, and she wanted a male hero this time, but worried about writing one. The answer, in her account, “just kinda popped into [her] head”: make him half-female. The switching mechanism came from the cloth noren curtain at a bathhouse entrance; she considered having Ranma change every time he was punched before settling on water, and water required the cursed springs of Jusenkyo to be in China, the only place she felt could hold such a thing.

Asked by Animerica in 1993 whether the sex-changing theme was meant to enlighten a male-dominated society, she declined the premise of the question: she does not think in societal agendas, she said, and had simply wanted “a simple, fun idea”, as a child she had felt that humans turning into animals might be fun, like a fairy tale. Her editor initially asked for a more dramatic series; she felt that register was not hers, though she has acknowledged that drama arrived in the work anyway toward the end.

One more of her rules survives into both anime: sitting in on the voice auditions, she insisted that male and female Ranma be played by different actors whose gender matched the form.