First in line to marry Princess Ayeka. Seiryo was authorized by the Jurian Emporer Azusa to marry his eldest daughter and become first in line for the throne.

Before Yosho left Jurai never to return, Yosho was going to marry Ayeka. Although Yosho disappeared mysteriously. 700 years after his disappearance Azusa became concerned that he had no male heir. Azusa selected Seiryo a scarcely trained memeber of the royal family to marry her. Azusa hates Tenchi and doesn't want to see the grandson of his deserting son become Emporer.

Seiryo himself is a conceited, insensitive, and possibly has homosexual tendencies. All though he is somewhat skilled in the art of Jurain swordsmanship, he is definately nobody that should be sitting on the throne. Most of his powers focus around making his appearance better and cannot be used for any type of combat.

He is defeated when he challenges Tenchi to a dual. The winner would get Princess Ayeka's hand in marriage. With all the girls rooting for him, Tenchi got his sword and was getting ready to fight Seiryo. Tenchi didn't want to fight Seiryo, but the girls all wanted him to for their own reason. But just before the battle began, Mihoshi came plummeting out of the sky and landed in the lake. This caused a giant tidal wave which washed Seiryo away. No word as to whether or not he survived, although he was seen floating in the lake shortly after possibly simply unconcious. They probably brought him back with them regardless of his losing the dual.

From Tenchi GXP:

Seiryo does posses a superior mind and excellent fighting prowess, but his over the top nature usually sabotages any of his grand designs. As punishment for an unspecified infraction, the bombastic and outlandish Seiryo is more than eager to take out his frustrations on the new Earthling recruit, Seina. Typically the people of Earth are considered not ready to accept the duties and rigors of being a member of the Galactic Police, something Seiryo reminds Seina of all too often. Seiryo considers himself superior in every way and is not afraid to tell anyone so, especially Amane, whom he desires more than anything else.

This info was excerpted from the Tenchi Muyo GXP website