Sakuya

Sakuya is a new character introduced in Tenchi in Tokyo which is also known as Shin Tenchi Muyo. She is the first character who Tenchi falls in love with. As you can imagine this does not go over very smoothly with the girls back at the house. Specifically Ayeka and Ryoko. While Sakuya is a normal human she is putting herself in danger by getting involved with Tenchi. After all he's on the hit list of many an alien villain. Not to mention the danger involved in getting in the way of Ayeka and Ryoko.
She is attending a college in Tokyo. She is one of the most popular girls in school and there's a lot of word going around the school about the new guy who has stolen the heart of the girl that has yet to be impressed.

Sakuya is a shadow (incarnation) of Yugi. This means that Yugi and Sakuya are the same person, sort of like Sasami and Tsunami. Yugi sent Sakuya to interfere with the bond between Tenchi and the girls. By doing this the crystals that make up the sword become less powerful. Sakuya has no memories of her childhood, parents, or even how she got to Tokyo because she never experienced these things.