Sasami is the youngest of the Tenchi cast (well, eight and 700 years of being cryogenically frozen) and my second favorite Tenchi character. She comes from Jurai (don't we all) and is Ayeka's little sister (doesn't really look it, does she?) so she is also a member of the Jurai royal family.She's always playing with Ryo-Ohki and is just about as carefree as Mihoshi.
Even though she's the youngest (sort of, even though she's over 700 years old) she's the one who does the cooking. She first appears in ep. 2 of the Tenchi Muyo! RYO-OHKI series with some sort of cute white squiggily pet of hers. Tenchi was locked in a cell (that's supposed to be prison?? Man, most heavenly cell I've ever seen) and she lets Tenchi out because she wants him to play a game with her. He gets in big trouble (and so does she) but she enjoys it all very much.
As for Sasami 700 years ago... that's a little mysterious. When Jurai was being attacked by the 'space pirate' Ryoko, she found a room full of Jurai's trees. Naturally, she went around talking to the trees, saying hello and all that, enjoying herself while her lady-in-waiting was getting an ulcer worrying about her. She got a little close to the edge of one of the platforms, and she would've been okay if it hadn't been for a ship that hit the side of the building and shook the whole place. She plummeted to her death.
At least, what would've been her death, if it hadn't have been for our (second) favourite goddess, the great and powerful (and beautiful) Tsunami.
Tsunami assimilated with Sasami to keep her alive, and all went just fine until seven hundred years later, when Sasami began to wonder just who she really is. She thinks of herself as Tsunami's creation, but she is the real Sasami. Don't worry, this all gets cleared up in episode #8 of the OVA series.
Anyway, she and Ryo-Ohki are always playing together and for some reason they're so cute together it just looks ever so very right.
Sasami is in love with Tenchi (as are all the other girls) but she seems to have a better chance even though she's younger than him. For one thing, she's nicer than either Ryoko or Ayeka, she's smart and a good cook, she's cute, and since she's assimilated with Tsunami when she grows up... she'll look like Tsunami! (Now this is interesting, eh?)
Sasami has gotten to be the main character in some of the most interesting (and best) episodes in all of the Tenchi Muyo series'. For example, in episode #18 of the TV series (No Need for a Ghost!) she got to play opposite the most popular one-time Tenchi character to date, Mirei. Mirei is a girl who 'lives' on one of the ships in the Sargasso Sea, a place in space full of dead/wrecked ships. When they were in the Sargasso sea they spent the night there. In the night, a strange girl named Mirei comes to Sasami and brings her aboard one of the 'Dead Ships.' Sasami befriends Mirei (the girl) and it turns out that Mirei is a ghost. They have a great time, and there are some parts of this episode which are particularly touching and cute, it's one of the best of the more emotional episodes. (I like the sticker thing, don't you?)
Sasami also got to star in her own series of special episodes, the two episode special entitled 'Pretty Sammy , Magical Girl.' I'm afraid I don't know much about this one, but I do know that in theses eps. Sasami can transform into 'Pretty Sammy', which is like Sasami only with a different costume and rather, eh, interesting 'super powers.'
Sasami always seems to be saving Tenchi when everyone else forgets about him, and always seems to be doing, eh, stuff with him that Ryoko and Ayeka want to be doing (like exchanging bites of sweet potatoes with him and getting to sleep over in his room {along with me, the great Washu.})
They have a special relationship right now, and when she grows up it should be interesting to see how their relationship develops...