Tenchi Muyo! (天地無用! Tenchi Muyo!), is an anime and manga series about a boy named Tenchi Masaki and the alien women that love him.

The original series, Tenchi Muyo! Ryo-Ohki, was a six episode OVA (Original Video Animation or Direct-to-Home Video) series; released in Japan in 1992–93. As its popularity grew, it spurred a seventh episode (also known as the Tenchi Special) and the standalone Mihoshi Special. In 1994-95, the second OVA series was created and released, featuring episodes 8–13. From 2003 to 2005, a third OVA series was released, with episodes 14–19, centering around the three goddesses introduced in the second OVA series. This is then followed by a special twentieth episode which centered around some of the remaining plot threads towards Tenchi's mother, as well as Noike, who was introduced in episode 15. The series can be somewhat confusing to newcomers because it has several continuities, although due to later creative changes many consider the original OVAs 'true' canon.

Before the popularity of series like Love Hina, to American fans Tenchi Muyo! set the benchmark for a series with a somewhat meek but kind male lead surrounded by attractive but often bizarre women, an anime subgenre (harem comedy) which would later become common. The TM franchise is also well-known in having a manga developed after an animated version was released, when typically the reverse is true.

Tenchi Muyo! was one of the early successes for AIC, the animation company behind it, which went on to create El-Hazard, Battle Athletes, Oh My Goddess!, Dual! Parallel Trouble Adventure and many other anime series. The main artist for the series is Masaki Kajishima.

The name of the manga is a play on words. Tenchi muyo (天地無用?) in Japanese means "This way up", a phrase written, for example, on boxes to show they should not be upturned. The word muyo also means "unnecessary", thus with a lead character "Tenchi" this name could also mean "unnecessary Tenchi" and is more often than not translated to "No need for Tenchi" (even so far as the episode titles for the "Universe" series to have the running gag of having the titles start with "No need for...")

The three major series continuities are Tenchi Muyo!, Tenchi Universe, and Tenchi in Tokyo. The first series, TM!, is the original OVA (Original Video Animation) which introduces the core characters. The other two are spin-offs that utilize the same characters, with the addition of Kiyone Makibi, though the backstory is quite different from the original OVAs. The first of the spin-offs was Tenchi Muyo! TV (also known as Tenchi Universe), in 1995; it is a twenty-six episode TV series that retells the original series differently. This anime was one of few anime to be broadcast on PBS member station KTEH San Jose, according to the ANN.

Tenchi in Tokyo (Shin Tenchi Muyo! in Japan) is a 26-episode anime series produced by AIC and Pioneer Animation (now Geneon Entertainment) in 1997. It is one of the many spinoffs from the Tenchi Muyo! series. It aired in North America on Cartoon Network's Toonami block starting in the fall of 2000.

Unlike the previous series, the second TV series is completely unrelated to the initial concept of Tenchi Muyo! and is completely different from the OVAs and first TV series. A couple of changes are that Tenchi and his grandfather are not related to Jurai's royal family, and the secret behind the Masaki family in this series is to protect the Earth from evil as Planet Guardians. Many of the returning characters were also given completely different personalities that makes them different from the previous series. One final new change is that all the girls are introduced in the first episode and then in episode 7 to show how they all met Tenchi, rather than introducing them separately as shown in the previous series.

- From Wikipedia