Ranma Satotome is cursed by the mystical waters of Jusenkyou to turn into a very attractive, female version of himself. This happens to him any time he is doused with cold water. As one might imagine, this causes some problems for him.
When he was very young, his father Genma promised his best friend and training partner, Soun Tendou, that his son would be married to one of Soun's daughters. As part of the marriage agreement, Ranma would inherit the Tendou family's dojo, and take up where Soun and Genma had left off.
Soon after, Genma took Ranma on a series of training journeys throughout Japan and China to teach the youth the ways of "Anything Goes Martial Arts". Ranmas' mother, Nadoka, missed her son horribly. Even though she missed him, they agreed on the basis that Genma thought that his mothers' tender love would ruin the young martial artist, because it make him soft and weak. So, Ranma became a fearsome martial artist, equal if not better than his father. Along with all the other styles of martial arts, Ranma learned and became very skilled in Kempo, an acrobatic discipline. It was on the last of these journeys that Ranma and his father both acquired curses from Jusenkyou.