Tenchi Muyou! Ryououki

Tenchi Masaki grows up hearing that an ancestor once used a sword to seal a demon inside a cave seven centuries ago. Curiosity eventually draws him inside, where he removes the legendary blade and releases the prisoner himself. The "demon" is actually Ryouko Hakubi, a powerful space pirate who has been trapped there for centuries.

When the sword awakens a hidden power within Tenchi, Ryouko takes an immediate interest in him, and one extraordinary visitor soon leads to another: Jurai princesses Aeka and Sasami, Galactic Police officer Mihoshi, and the brilliant Washu. Tenchi's rural home suddenly becomes the center of alien rivalries, family secrets, and powers he never knew he possessed.