From Viz:
The trouble and fun began when ordinary teenager Tenchi Masaki inadvertently released the legendary demon Ryoko from his grandfather's shrine. Turned out Ryoko was actually a marooned space pirate! Since then, she's become Tenchi's unwanted houseguest, attracting a host of other troublemaking alien women: Ayeka, a haughty alien pricess; Sasami, her mischievous little sister; and Washu, Ryoko's mad-scientist "mother." Add Ryo-oh-Ki, an adorable little carrot-eating spaceship, and you've got one full Shinto shrine!