In case you are new to the world of Tenchi Muyo!, you will notice one major pattern in the series - All of the titles begin with "No need" (No need for an arch rival, no need for a carnival, etc.) This plays off of the fact that Tenchi Muyo means No need for Tenchi, who is the main character in the story. Tenchi Universe is a hillarious comedy about a young man named Tenchi who gets an unexpected visit...An alien ship crash lands near his home.
The story begins with a space ship crashing near Tenchi's home. The inhabitant of the space craft is a young woman named Ryoko. Ryoko plays the role of an adventurous, yet somewhat innocent prankster. She has an affinity for Tenchi and hangs all over him. We learn that the reason the ship crashed is that Ryoko was being chased by another ship. The inhabitant of that ship is a pretty, but ditzy space detective named Mihoshi. Mihoshi points out that Ryoko is far from innocent (she's actually a space pirate who's wanted bt the law.) Ryoko easily outsmarts the dizzy cop on more than one occasion. A day or so later, another ship lands. This is the ship of princess Ayeka of the planet Jurai. She is Ryoko's mortal enemy, and she too takes a liking to Tenchi. (The bouts these two have are outrageous!) Princess Ayeka's landing was followed by the landing of Sasami, Ayeka adorable little sister.
The fun doesn't stop there. One day, Ryoko stumbles upon a cave which Tenchi's grandfather points out to be the home of a demon. They were advised not to enter the cave. Being the rebellious and adventurous type, Ryoko enters the cave and drags Tenchi with her. The two stumble upon a large, crystalline structure which they assume is the demon's home. Suddenly, Ryoko is overcome by an urge to educe Tenchi, as just as she approaches him, Ayeka, Mihoshi and Sasami find them. Needless to say, Ayeka is pissed. She and Ryoko begin to argue and in the heat of battle Ryoko breaks the crystalline structure. (We find out here that Ryoko is VERY strong!) A female figure rises from the rubble. Enter Washuu, a genius scientist who was exiled from her home planet because she made a few planet destroying weapons. Washhu also moves in with Tenchi, which makes his father really happy.