It starts on a rainy day when Ranma learns he's betrothed, and he doesn't take it well. Regardless, his father drags him into the ordeal, literally kicking and screaming.
Switch to the Tendo Dojo, home of the betrothed. There live the three sisters, one of whom is supposed to wed this unknown boy. And they are worried, eager, and completely bent about it (Kasumi, Nabiki, and Akane, respectively). But they don't get much more thought about it until the aforementioned Ranma is brought through the front door, kicking and screaming.
Oh, and he's a girl.
The Tendo patriarch quickly deciphers this and passes out. Akane, the youngest daughter, is oblivious to the panda and her father, though. She's more concerned about her older sister, Nabiki, feeling up poor Ranma to justify refusing to be married to another girl (as well as secretly coping a feel to satisfy her lesbian tendencies). And so she offers to spar with girlish Ranma to let off some tension. Ranma hesitantly accepts.
So they spar. And by spar I mean Ranma dances around Akane. And she acknowledges this, and expresses that she's glad Ranma is a girl dancing instead of a boy, because she knows that it will make her the uke in bed by default (note the trend I'm building on the Tendo daughters, here).
This of course, floors our hero. Who ponders it over a hot bath.
That Akane walks in on.
By the way he's a boy, now.
Panic. Violence. Lolmedy.
And this is how Ranma 1/2 begins. a seven-season, 12 OVA, two movie, 38-volume manga epic about the boy who becomes a girl when splashed with cold water. And the girl that loves to beat on him. And the girls that would love to be his baby's daddy. And the numerous antagonist that are really mad at the fact that they can't get the girls that are so willing to throw themselves into Ranma's sack.
Let's not forget the panda, though. :3
In other words, it's all about Ranma's misery. From the multiple fiancees, to the feuds held over everything from women to bread, every minute is jam-packed with Ranma's misery, embarrassments, and eventual victories.
Ranma is, of course, the key character. He's been training since he could crawl in the Saotome branch of the Anything Goes school of martial arts. But his father is an idiot, greedy, cowardly, and a swindler. Out the gate, Genma puts Ranma into a compromising deal in order to really start his training. And over and over again, through the harsh punishments that the fat man referred to as "training", Genma has done neglectful and evil things to the poor boy. Including and not limited to: multiple fiancees, stupid, berserk training techniques, trading the boy for food (see the icon keywords, they do not lie), stunting his education, and cursing him on several different occasions. Truly, Genma is one of the Worst Anime Fathers of All Time (it's arguable that he is leagues above heartless bastards like Patrick Zala and Gendo Ikari. Because none of them bonded with their offspring.)
But Ranma's a toughie, and beats on his father regularly. And becomes one hell of a martial artist. And, most confusing of all, he's high-spirited. And happy-go-lucky. He gets his worry points, and is prideful, but he's not a rolling ball of depression, despite all that's been done and all he has done to himself in the name of pride, honor, and the art. This includes getting away from his mother for training by signing a fucked up contract that says if he does not return as a "man amongst men", he has to commit ritual suicide.
Really, for the hysterical junk he has to go through, he's very upbeat about it all. He's also pretty dependable when someone's in a jam, and doesn't like having to pick on opponents weaker than himself. Something of an honorable martial artist, or as honorable as the Anything Goes school can allow him to be.
But of course he's got to vent, and what he doesn't take out on dear old dad, usually ends up spilling over into one Tendo Akane's direction. She is the one that eventually gets engaged to him, despite her kicking and screaming. And hitting Ranma over the head with a table. And she indulges him in kind, often getting into arguments with Ranma that gives them their own rating in terms of domestic disputes (which might explain why the cops never, ever come around).
He does bond with her, though, and does a lot of stupid things to protect her, as well as a lot more to tease her (the Romeo and Juliet debacle, as well as the Golden Pair battle come to mind). To those not in the know, Ranma and Akane are the old school Inu-Yasha and Kagome. Only if Kagome were more violent.
And then there are the numerous cracked satellites that orbit their strange relationship: Hibiki Ryouga, the boy who gets lost easily, takes massive damage, and sleeps with Akane in pig form (see: Jusenkyo Curse). Shampoo, a Joketsuzoku warrior Ranma is technically married to because he beat her in combat for a free meal. Mousse, Shampoo's eternal fanboy. Cologne, her great-grandmother who's just fuggin' amused by ALL OF THIS. Happousai, creator of the Anything Goes style, and master of the Ecchi Intent. Kuonji Ukyou, Ranma's childhood BFF who is also engaged to him. The Kuno family, who bring their own speshul brand of insanity to the table.
Really, it's a never-ending circus. Rivalries, silly plots and sillier plot objects, and martial arts styles you never ever heard of, before (Martial Arts Cheerleading, Tea Ceremony, Skating, Gymnastics, Take-Out, etc). All that and some bad cooking. ♥
Okay, so one time, Ranma actually went to school. Shock and horror, really. And in this school, the lunchtime was a literal war zone. Like Oliver Twist meets American Gladiators. Everyday, they would somehow run short on food, so everyone not strong, fast, and tough enough to get fed just went hungry.
Ranma, fortunately, met the prerequisites.
Unfortunately, some people don't like being lower on the food chain. Hibiki Ryouga is one of these people. Everyday, Ranma beat Ryouga out in getting food, and everyday, it pissed him off more and more. Not that Ranma cared--it's never personal when it comes to his stomach, after all.
But all of this eventually came to a head. Hibiki would no longer stand for Saotome getting his daily bread. And so he challenged: Open lot, behind the Hibiki residence.
He trained for it, got psyched up, and promptly got lost over the next week trying to find it.
...
Oh, I forgot to mention: Ryouga has the worst directional sense in the history of EVAR. Couldn't find his way out of a bathroom stall with a GPS unit surgically grafted to his eye.
This meant that Ranma spent three days in the place of the duel, waiting. And waiting. And waiting. And then he gave up and found something else to do.
But Ryouga showed up on the fourth day, mad as a hornet. And decided to track Ranma all the way to China. And Jusenkyo.
And their relationship gets worse. :3
Wandering the cliffs of Jusenkyo, an at-that-point uknown angry girl was chasing down a panicky, fleeing panda. And she blindsided Ryouga. Who fell into the spring of drowned piglet.
His life was hell from then on in. And this is how he reunites with Ranma, ready to tear him a new one because he couldn't let go of a silly bread feud that went awry.
Again, not that Ranma cared. He actually considers Ryouga a good friend and very decent sparring partner. He hardly hold ill will over the murderous rage that the young Hibiki possesses. Except when it comes to Akane.
This is explained because Ryouga tracked Ranma to the Tendo Dojo (don't ask how, it will only hurt your head trying to figure out why he knew where to look in the first place), and fought him on a rainy night. The same night that Ranma found out about Ryouga's curse. And Akane didn't.
Instead, she found a little black piglet to boobsquish and undress in front of. Which, of course, is a double irritant for Ranma. He CAN'T tell Akane that her pet P-chan = Ryouga, out of an honor promise he made with the boy. Not that he hasn't indirectly tried, on numerous occasions.
Plus, the eternal lost boy has something of a huge crush on Akane, which further drives Ranma up the wall.
This enflames their rivalry. When these two box, buildings collapse and mountains get indentations. Ryouga is a walking powerhouse, and takes tank-denting punches like people pop tic tacs. Ranma is fast, and while not a slouch on power, has tomes of skill over the more erratic Hibiki. And then they went and got direct ki attacks, which just made things helluva worse.
Yet, despite all of this, as well as Ranma's constantly teasing, confusing, and just plain outwitting Ryouga, they are indeed BFF. Go figure.