Tenchi_synopsis

Tenchi is an average Japanese high school student. Until, that is, he unleashes a demon that was imprisoned in a cave 700 years ago by his ancestor Yosho by taking the Master Key, a sword that Tenchi thinks is "a rusty old piece of junk", which he then manages to break on a rock with a warn on. The demon he releases is Ryoko, The Devil Caller. She uses him to let of steam for being trapped in cold, dark cave for 700 years, but is beaten by Tenchi when the Master Key activates as a light sword. He goes home, seeing as he's just wrecked the school, but finds her sleeping in his bed.
Tenchi is soon joined by an entourage of cute alien babes:
The princesses of Jurai, Ayeka and Sasami who came to earth in search of Ryoko who is responsible for the disappearance or Ayeka's fiance. Ayeka's ship is destroyed in the battle with Ryoko, and they are stranded, but choose to stay when the king and his wives arrive to take them home.
Mihoshi, member of the Galaxy Police and total ditz and bubble head. Nuff said.
And Washu, the number one genius scientist in the universe, insistent on making Tenchi her Little Guinea Pig.
Finally, Ryo-ohki, who technically is a spaceship, but comes in flat pack, in the shape of a cabbit. Likes hangning around with Sasami and pretending to be a hat ^_^
Also making an appearance in the OVA, movies and other spin off series, Kiyone, Mihoshi's long suffering partner.

In this wacky house, Ayeka and Ryoko fight constantly with each other for Tenchi, Sasami cooks a lot, mihoshi just drifts around, Washu does her science thang, and Tenchi tries not to get caught up in it! Along the way, they fight the infamous space villain Kagato, battle with the evil Dr Clay and sort out all the rest of the problems that come with being the grandchild of the first crowned prince of Jurai.