Basically, the protagonist is Saotome Ranma, a 16 year old martial artist who spent the great majority of life training in the arts. Along the way, his idiotic (I really don't like him) father, Genma drags him to the Cursed Springs in China called Jusenkyo. Should you fall into one of the many springs there (and given Murphy's Law, Ranma and his dad DID fall in), you get turned into whatever drowned in the spring last whenever hit by cold water. Hot water changes you back.

NOW, on top of the fact that Ranma's now cursed to turn into a redhead girl, he managed to pick up at LEAST 4 contant fiancees, and at LEAST 4 mortal enemies (all of whom are in some way related/love one of the previously mentioned fiancees) and his idiotic panda of a father (guess which Spring Genma fell into?) keeps pushing him to marry Akane, (one of the 4) a tomboy who seems to like to mallet Ranma over the head at the slightest mistake (ahh... anime...).

Chaos and mayhem soon follows, etc. etc. and there's just too much about his life to list, so I'll stop now. :)

Ranma 1/2 is copyrighted to Takahashi Rumiko and other respective owners. No infringement intended.