Ranma is the story of a boy who went on a training trip with his father to China. There he fell the the cursed spring of Jusenkyo, and now he turns into a girl when he gets wet. That's not his only problem, thanks to his father he was engaged at an early age with one of Soun Tendo's 3 daughters. Upon arriving back in Japan the Tendo family realize about Ranma's curse. Akane being the youngest one is picked to be his(her?) future wife.

Ryoga is Ranma's greatest rival, he also fell to into the cursed spring of Jusenkyo. He turns into a small black piglet. Ryoga loves Akane but is too shy to tell her. Fortunately for him Akana adopts him as a piglet and calls him P-chan. Akane doesn't know Ryoga and P-chan are the same and Ranma promised him not to tell her. Ryoga is constantly traveling and has a terrible sense of direction. He often gets lost in the weirdest places.

The story of Ranma doesn't go through many significant changes so the characters can be taken from almost any point in the series.