In the original OAV series, Tenchi Masaki's troubles begin when he accidentally breaks a seal imprisoning the demon (and space pirate) Ryoko! After 700 years stuck under a rock, Ryoko's naturally bad temperment is even worse, and she wants to take it out all on poor Tenchi! While he's still fearing for his life, he meets Princess Aeka of Jurai, who happens to consider Ryoko her mortal enemy. The two girls get into a huge battle with their mammoth spaceships, and end up stranded on Earth after both ships are destroyed. Tenchi now has to deal with a powerful demon, a depressed homesick princess, and a younger, constantly cheerful princess (Sasami) - all under his roof!
Meanwhile, Tenchi alien heritage is revealed and his mysterious destiny is set into motion when the dangerous space criminal Kagato appears! Hot on his heels is Galaxy Policewoman Mihoshi, but since she's a klutz and a ditz, she's less than useful in capturing her quarry. The brilliant (but weird) scientist Washu appears on the scene with surprising revelations about Ryoko's origins, and aids Tenchi in saving the world from Kagato's destructive plans. Tenchi's full potential is revealed in the stunning formation of the legendary "Light Hawk Wings," which can only be produced by members of the Jurai Royal Family. The incredible event answers questions while bringing up entirely new ones that may change Tenchi's world completely.
In the continuation of the OAVs, romance is in the air, and as the Masaki household quiets down, the girls begin competing for Tenchi's affections! When things seem to be settled, the evil scientist Dr. Clay appears and creates a clone of Ryoko ordered to assassinate Tenchi. However, it's up to Washu and Tenchi to confront Dr. Clay and reveal his ulterior motives under the supervision of Queen Tokimi, a supernatural being with a mysterious interest in Washu.
The fun starts all over again in the Tenchi Muyo television series! This story takes place in a different universe from the OAVs, so the girls' relationships are slightly changed. In the first TV series, Ryoko's arch-nemesis Nagi is introduced and the truth about Tenchi's grandfather and his connection to Jurai is revealed! In the second TV series, better known as "Shin Tenchi Muyo" or "Tenchi in Tokyo," Tenchi starts a new life in Tokyo, leaving behind his chaotic home in the country and meeting new friends - most notably, Sakuya Kumashiro, a cute and energetic classmate. Soon, Ryoko and the other girls follow Tenchi to the big city to keep an eye on him. A suspicious new villain name Yuugi befriends Sasami, but seems to have a special connection to Sakuya.
The three Tenchi movies each follow after a series. The first movie, "Tenchi in Love," Tenchi starts to disappear! Deciding that something happened to Tenchi's mother in the past, the entire gang travels back in time to save Tenchi's existence! In the second movie "Daughter of Darkness," the mysterious Mayuka, calling Tenchi "Daddy" and causing a lot of problems in the Masaki household. She seems to be involved in a plot of revenge on Yosho, Tenchi's grandfather. In the third and last movie, "Tenchi Forever," two years have passed since the end of the second TV series and Tenchi continues to go to school in Tokyo. However, he has no memory of everyone back at home, and he is now living with a girl! Ryoko, Aeka, and Washu must figure out what has happened before Tenchi is lost to them forever!