Brief Synopsis:(note: I'll only be covering mainly the OAV, there are some differences between this and the TV series)
Tenchi is just your ordinary high school in Japan who occaisonally spends time at his grandfather's shrine, which is located in the countryside outside of Tokyo. His life is pretty normal until one strange girl after another starts dropping into his life(Some of them literally DROP in!). All in all, he ends up with 6 or 7 girls who begin living with him, his father, and his grandfather at his father's house, which starts in Tokyo but ends up next to his grandfather shrine in the hills (I won't reveal how this happens, but you'll see!). From then on, they somehow get involved in one adventure after another. I'll list the major players down below so you can get a better idea of who the characters are. Also, almost everyone has some sort of special powers or abilities that stand apart from the others.
Name: Tenchi Masaki
Sex:Male
Age:18, I think
Special abilites: Able to use the sword of the Light Hawk(A kind of light saber), and can generate the Wings of the Light Hawk(3 shields that protect him).
Episode introduced:#1
Name:Ryoko
Sex:Female
Age:at least 2000 years old, but appears to be 18-20.
Special abilites: Can Fly, teleport(to any place she's seen), throw energy blasts, and create an energy sword similiar to-but as powerful as-Tenchi's sword. Can also pass through obstacles like walls and can use elements(like water) to create demon like monsters. Needs at least 1 of her 3 special jewels to use most of her powers, located on her wrists and neck. Though needs at least 2 to control any demon-creature she creates!
Episode introduced:#1
Name: Ayeka
Sex:Female
Age:At least 700, but appears to look 20
Special Abilities: Can summon and control guardians (they look like blocks of cut wood) that function as some sort of entrapment shield. Can also create a sort of force bubble shield and use invisible force blasts. Her two main guardians have personalities and are named Azake and Kamidake and are considerably bigger.
Episode introduced:#2
Name: Sasami
Sex:Female
Age: Also around 700 (she is Ayeka's little sister), but appears to be 8
Special abilities: Not real evident, but include having visions in her sleep and a link with Tsunami, the most powerful (and living) Jurai ship(and source of all Jurai power, I think). Has a special symbol on her forhead because of this.
Episode introduced:#2
Name:Ryo-Ohki
Sex:Unknown, but I think female
Age:Unknown, but reproduces itself when it is near death.
Special abilities: Ryo-Ohki is a cabbit, a kind of cross between a cat and rabbit (and as such likes carrots, lots and lots of them!). Can change into a spaceship form. Don't ask me how it goes from a little cabbit to a huge ship! Also, can pass through solid objects, at least on the second try. :)
Episode introduced: #2(in spaceship form) - #3 (in cabbit form)
Name: Mihoshi
Sex:Female
Age: 23
Special abilities: Mishoshi is a member of the galactic police, and as such has access to some impressive weaponary and devices. However, she is a quite a bit of a ditz and a klutz (Hey, she's got blond hair...ok, so it's yellow but check her roots!) No real special abilities, however I've heard it mentioned (and I agree) that her klutziness is a special ability. With it, she defeats enemies on accident and can and will wander into almost anywhere. Even into areas where someone's not supposed to able to get into! For instance, Washu(mentioned down below) has a lab in subspace and supposedly no one can get in without her knowing it. Naturally, when Mihoshi goes looking for Washu to tell her it's time for dinner, she somehow ends up in Washu's lab, much to Washu's surprise!
Episode introduced:#4
Name:Washuu
Sex:Female
Age:20,000 years old!(approx.), appears to be 12, but can appear to be older when she wants too
Special abilities:THE technical scientific genius of the entire galaxy(self-proclaimed and I have no reason to doubt her! Hey, how smart would you be after 20,000 years? :). She maintains a huge lab in subspace and can move the entrance to her lab around wherever she wants; currently it's located in Tenchi's house. Can create and use almost anything technical and can anticipate almost anything. Also has powers similiar to Ryoko's(hey, she's Ryoko's mother), but rarely uses them.
Episode introduced:#6 I believe
I'll add some more stuff later!