On a ten-year training mission with his father in China to perfect his martial arts skills, Ranma fell into the Jusenkyo cursed Spring of the Drowned Girl and as a result turns into a buxom teenage girl (Ranma-chan) when splashed with cold water. He returns to boy form (Ranma-kun) when splashed with hot water. Ranma
will do anything to be rid of the curse and return to normal.

Ranma is generally an insensitive lout, but a skilled martial artist and incredibly strong. The only one capable of besting him regularly is Master Happosai and Cologne. He is heir to the School of Anything-Goes-Martial-Arts and will do literally anything to win a competition. There is no depth to which he will humiliate himself to win.

He is engaged to Akane Tendo and lives with his father at the Tendo's. He also attends Furikan High School with her and Nabiki Tendo. Ranma-kun is chased after by girls and by the fourth season he has managed to rack up a total of three finances and have several others chasing after him. This ability has also generated numerous enemies. Although he says that he can't stand an ‘uncute tomboy' like Akane, he becomes fiercely jealous when another guy shows her attention.

Ranma only has one fear - cats. When confronted with a cat he becomes stricken with fear, however, if he is unable to get away, his fear psychologically transforms him into a vicious cat, unleashing his cat fist technique 'Cat-Fu'. Cat-Fu renders Ranma invincible, enabling him to defeat anyone and anything (i.e., Happosai and Cologne). He may only be calmed down to normal by laying in Akane's lap.

He also has the habit of standing on his opponent's heads in greeting.

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