Saotome Ranma, a teenage martial artist, and his father Genma travel to the 'cursed training ground' of Jusenkyo in China. There, despite the warnings of the Chinese guard, they fall into the cursed springs. From now on, whenever Ranma is doused in cold water, he turns in to a girl, and a cute, well-built red-head at that. Hot water changes him back into a man again, but only until the next time. To make matters worse, his father engages him to Tendo Akane, a girl who hates boys.
This is basically the same as "Birdy The Mighty DECODE", only that it was made long before the other series (This in 1996, DECODE in 2000), has different art, the plot has some minor changes, and has everything packed into 4 episodes (OVAs).