Ryoga and Ranma were classmates in junior high. Ranma had a habit of grabbing away food before Ryoga could eat it; for this offense, Ryoga challenged Ranma to a fight in the vacant lot behind his house. But Ryoga, who has absolutely no sense of direction, couldn't find the appointed place until four days later. By this time, Ranma had gone off with his father on a training expedition to China.
Ryoga followed after Ranma and eventually found his way to Jusenkyo. There, a pigtailed girl chasing a panda knocked him off a cliff and into one of the cursed springs. He transformed into a small black piglet. The panda then tried to cook him for dinner. Fortunately, boiling water reversed his curse before he could be eaten.
Ryoga eventually found Ranma back in Japan and tried to kill him several times for revenge. He ended up in Akane's room in his cursed form, and she adopted him as her pet P-chan. Ranma soon discovered the truth, but his honor wouldn't allow him to tell Akane.
Personality: Ryoga is in love with Akane, but he has been unable to express his feelings to her. He is terribly shy when it comes to women, partly because he feels that they would never love him with his curse. He still hates Ranma, though now it is more due to their rivalry over Akane. They are able to work together when necessary, though not without a certain amount of distrust and friction.
Appearance: In human form, Ryoga is a big muscular guy. He wears a yellow headband with random black squares. As P-chan, he is a very cute, very small miniature black pig. The bandana becomes a collar in this form. He has fang-like teeth, even as a human.