Cake and Seeiw have been friends as far as they can remember. Cake is very outgoing and has a lot of friends while Seeiw is very shy and barely speaks to people he's not used to being around. Despite their different personalities, they are very close. By being next-door neighbors since they were born, they became an essential aspect of each other's lives. However, as they become older, things change and so do the way they see each other.

Ranma Saotome, 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 into a girl and a cute, well-built redhead 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 Akane Tendo, a girl who hates boys.