The original continuity of the Tenchi Muyo! franchise, consisting of three six-episode OVA series and two special episodes. The spinoff series Tenchi Muyo GXP and Isekai No Seikishi Monogatari (aka Tenchi Muyo! War on Geminar) are a part of this continuity.The first series, released from 1992-93, was mostly introductions to the major characters, who join Tenchi's Harem via a Debut Queue. Episodes 5 and 6 bring in the first major villain, the space criminal Kagato. The second series, from 1994-1995, includes some major revelations about the characters' pasts and features a new villain, Dr. Clay. The third series, from 2004-2005, focuses more on the characters' families and resolves some lingering issues from the first two parts.
All There in the Manual: Masaki Kajishima released several Doujinshi and Light Novels expanding on the background of this continuity; part of the reason for GXP was to help explain some of this to the anime-only fanbase.)
Camp Straight: Seiryo Tennan, otherwise known as the pink-haired guy who almost marries Ayeka.
Chekhov M.I.A.: A very subtle example. In episode 4, Mihoshi's computer lists a few of Kagato's past crimes. If you pay attention to it as it fades into background noise, one of the crimes is the kidnapping of a "female student" from the Science Academy. Two episodes later, this turns out to be Washu (though of course she was actually a professor)
Mihoshi asks Washu if she is the students, and Washu face-faults. Her students are pranksters...
Insistent Terminology: Ayeka and Sasami's mother prefers her daughters calling her "Mommy". Ayeka is embarrassed about this, although her mother seems to be aware of this, not hesitating to deal with anyone who teases her kids over it.
No Export for You: Many Tenchi Muyo fans outside Japan don't view the entire series as a whole including the Doujinshi and Novels released by Kajishima-sensei. This causes them to miss out on important information, and the lack of this causes a severely ignorant case of Americans Hate Tingle.
The Other Darrin: Subverted in the 3rd OVA; Rebecca Forstadt had already replaced Ellen Gerstell as Mihoshi in Tenchi in Tokyo, as did Wendee Lee with Kiyone, who was previously voiced by Sherry Lynn (who continued her role of Sasami), Bob Papenbrook with Katsuhito and Nobuyuki, who were both previously voiced by Jay Hopper, and Mona Marshall had already replaced Petrea Buchard as Ryoko in GXP. Also played straight in the 3rd OVA with Mari Devon replacing Jennifer Darling as Lady Tokimi, although the latter did return to voice Ayeka. Michael McConnohie also replaced Jack Fletcher as D3.
In addition, all returning characters' voices were replaced with sound-alikes for their brief appearances in GXP. Of these replacements, only Mona Marshall as Ryoko became permanent, as the rest of the characters reverted back to their original voices for OVA 3. The only character voice to not be replaced is Rebecca Forstadt as Mihoshi, but even then, she was the SECOND Mihoshi. The original Mihoshi had retired years earlier.
Physical God(Sasami/Tsunami; also, OVA3 spoiler:Tenchi is revealed to be the earthly avatar of a being more powerful than the three goddesses who created the universe.)
Rake Take: Subverted in the first episode when Ryoko steps on a metal rake. She doesn't get hit in the face, she instead bends the pole by smacking it. This, however, leaves an opening for Tenchi to slice her wrist off.
Schmuck Bait: Deliberately used by Katsuhito in the first episode. He warns Tenchi not go down to the cave near the Masaki shrine, because he knows Tenchi will disobey and end up releasing Ryoko.