Tenchi is an average guy who just accidentally freed the space pirate Ryoko after 700 years of captivity! Attractive alien girls from all across the galaxy are about to descend on Tenchi and make his life more outrageous than ever imaginable!

The demonic space criminal Kain has escaped from prison and destroyed the Galaxy Police headquarters. To ensure that the Jurai will not stop him, Kain travels back to 1970 to eliminate Tenchi's mother before he is even born. Now, Tenchi and the gang must travel to the past to stop him before he ceases to exist.

One day, Tenchi disappears in the forest near his house. Six months later, Ayeka and Ryoko locate Tenchi living in a city, but with a mysterious woman. What's more, Tenchi appears to have aged several years. Whenever Ayeka and Ryoko catch up to him, he disappears into thin air, apparently existing in a fabricated alternate dimension where he has no knowledge of his past.

Mayuka is a girl who appears one day and claims to be Tenchi's daughter. As the initial shock wears off, everyone in the Masaki household gets used to Mayuka's presence. However, things only become more interesting as Washu tries to discover Mayuka's background. What Washu found involves demon, the Prince of Jurai, and unrequited emotions.