Ranma 1/2 is a manga by Rumiko Takahashi, who also made Maison Ikkoku and InuYasha. It's a very famous manga and anime, who was on French TV when I was young, so all my friends now the anime. But I only read the manga and watched few episodes few years ago...
In fact for this drawing I had an example and just copied it. Same for some drawings about InuYasha, Satan from Nora (another manga) and Momiji from Fruits Basket (another manga). I'm watching at the true drawings, made by the artist, when I draw them, so it's a little different than my other drawings... It's why they seem so good.