The eternally lost boy. Ryoga has no sense of direction and can get lost crossing the street. When they were children, Ryoga and Ranma went to school together. Every day in the cafeteria, lunch was considered a war (it being a boys' school). Ryoga seemed to always be in reach of the very last bread of the day, but Ranma always just beat him out to it. Ryoga challenged Ranma to a duel in the vacant lot next to Ryoga's house. He promptly got lost on the way there. Ranma waited three days for him to show up but went home and left on a ten year training mission with his father. Ryoga eventually got to the lot, but believing Ranma had ran out on him, he swore to track him down to conclude the duel. Following them to China, Ryoga was accidently pushed in to the Jusenkyo cursed Spring of the Drowned Black Piglet by Ranma-chan. As a result, Ryoga now becomes a small black pig when splashed with cold water. He blames Ranma for this curse and swears to destroy him.

Ryoga is literally the strongest man in the world. He carries a steel ribbed Asian umbrella and throws razor sharp bandannas. Tracking Ranma down to his high school, they fight but Ryoga is splashed and changes into a small black pig. Akane discovers him and adopts him as a pet, naming him P-chan. As a result, Ryoga falls in love with Akane but is too shy to tell her his true feelings. Ranma, feeling sorry for him decides not to tell anyone of Ryoga's curse. Therefore, Akane, sometimes to the point of stupidity, never discovers that Ryoga is P-chan.

Ryoga now jealously hates Ranma because he is Akane's finance and is constantly challenging him, but when both their interests are served is willing to team up with him. Ryoga is not the sharpest tool in the shed. Ranma-chan has successfully fooled Ryoga into believing she was his long-lost finance and his little sister to keep Ryoga and Akane apart. Ryoga is a tragic figure but has high morals and hates to see anyone weak picked on.