|Continuity||OVA (Tenchi Muyo! GXP)|
|Voice Actors||(Japanese:) Shigeru Mogi|
(English:) Tony Oliver
|Occupation||Galaxy Police Detective|
|Relatives||Mr. Yamada (father)|
Mrs. Yamada (mother)
Yoshiko Yamada (Sister)
Tenchi Masaki (Cousin)
Amane Kaunaq (co-wife)
Kiriko Masaki Jurai (co-wife)
Ryoko Balta (co-wife)
Neju Na Melmas (co-wife)
Kai Masaki (brother-in-law via Kiriko)
Mr. Kaunaq (father-in-law via Amane)
Mrs. Kaunaq (mother-in-law via Amane)
King Balta (great-grandfather-in-law via Ryoko)
Tenchi Muyo! GXP
Seina Yamada is a 15 year old boy at the beginning of the series. He is lifelong friends with Tenchi, Kiriko, and Kiriko's brother Kai. Before joining the Galaxy Police, Seina lived on Earth with his parents who run a small grocery.
Aside from Tenchi, Kiriko, and Kai, Seina has very few friends; mostly because he has what seems to be the worst luck in the universe. Minor disasters often occur in his presence, and anyone near him stays a good distance away from him. Seina's usual (lack of) luck almost ends when a spaceship nearly crashlands on his head at the Masaki residence. Its driver, the beautiful Galaxy Police Detective Second Class Amane, had meant to present Tenchi a pamphlet for joining the Galaxy Police, but mistakenly offers Seina the application instead, under the impression that Tenchi was training the boy.
His family persuades him - via forcibly nabbing his signature and thumb print - to fill out the application, with the hope that Seina would win a prize. When he wakes from sleep for the night, he finds himself aboard a spaceship, recruited to be the newest member of the G.P. Academy. He also meets Mitoto, the ditzy mother of Mihoshi and cleaning lady extraordinaire, before discovering his friend Kiriko is also a GP officer. From there, Seina is thrown into a plan to stop the Daluma pirate guild from taking over the galaxy.Initially, Seina's entrance into the GP was being fought against because he is apart of an underdeveloped planet (Earth), though he had the extremely helpful backing of galactic political figure Seto (aka the "Devil Princess of Jurai"), who took an instant interest in the boy. Lady Seto's interest in Seina comes from the fact that his luck attracted a large fleet of space pirates whom the GP were able to capture after dodging arrest for years. Seina also gained the backing of GP Board Director Airi. Initially, Kiriko is dead set against Seina staying with the GP out of her protectiveness for the boy, though she eventually relents while still being cautious with Seina remaining in space.
When Seina's bad luck was found to have an effect of attracting space pirates, the G.P. capitalized on it by placing Seina in command of one of the Decoy Fleet's newest ships, the Kamidake (which included systems designed by Tenchi's sister Tennyo). However, when the ship was irreparably damaged as a result of an encounter with space pirate Tarant Shank, Lady Seto then presented Seina with a ship designed by the greatest scientist in the universe, Washu, which was named the Kamidake II by Seina. The ship consists of the main ship body and a "cabbit" (cat/rabbit-like creature who acts as a biological computer unit) similar to the legendary Ryo-Ohki, named Fuku by Seina, meaning good luck, the complete opposite of Seina.Later, the ship became a hybrid, when under Lady Seto's supervision, it was fused together with Kiriko's second generation Juraian Royal Tree Mizuki (enabling it to generate Light Hawk Wings for protection). The main pod, which houses the royal tree in a Juraian Royal Tree ship, was used for the fusion.
Much like Tenchi, all of the girls in Seina's new out-of-this-world life; Amane, Kiriko, child-like high priestess Neju, and gentle former space pirate Ryoko, all fall for Seina and fight for his attention and heart.
Kiriko's love for Seina comes out in the open after basically having a hand in raising him, though at times she feels inadequate to the other girls; Amane, in the beginning, used Seina as the butt of her jokes, and used her sex appeal to play pranks on him and to push Kiriko and Erma's (who was really Ryoko in disguise) buttons, but gradually gained true feelings for him. Ryoko, a noble and infamous space pirate, also fell in love with Seina after running into him again and again throughout space because of his magnetic attraction to space pirates. After the Daluma Guild situation, Ryoko quit being a pirate and vowed to serve Seina for the rest of her days and was allowed to join the G.P. and the crew of the Kamidake; Neju, a 2000 year old high priestess (though she resembles a 10 year old girl), considers Seina her big brother and challenges the other girls for his attention. She continuously claims that she intends to marry Seina when she "grows up." Being that she is a target for kidnapping and assassination, it was decided that she would join the G.P. Academy and train aboard the Kamidake under Seina.
Battles with pirates and resulting revelations
During the time Seina commanded the Kamidake and Kamidake II, he was earning an equivalent to a fleet commander's salary. However, because he was still a cadet, that money was kept in a special account until he graduated and was given what he would normally earn. The interest the money accumulated, however, was forwarded to his family on Earth. It was so much money that the Yamada family used it to build a huge new home, as well as building a huge supermarket in place of their small grocery. While Seina was visiting Tenchi back on Earth, Amane, Kiriko, Ryoko Balta, and Neju, who was visiting at the time, worked at the Yamadas' supermarket, where they were worked until exhausted.
It was later in the series when Seina, who was trying to rescue Fuku from rogue elements of the Galaxy Army, was found by a tribe of Wau, who mistake him for their savior and threw him into an ancient mecha (which bears a striking resemblance to Zinv of Dual! Parallel Trouble Adventure'). Somehow, Seina was able to activate the mecha, which he used to save not only Fuku, but also cabbit clones made from Fuku's cells by Tarant, who had allied himself with the rogue G.A. faction. Angered by this, Seina fought Shank and his allies. But in doing this, the mecha was able to integrate itself to the Kamidake II, which was captured with Fuku. And even more startling, the mecha formed Light Hawk Wings, which are usually generated by the Juraian Royal Treeships, even though it was not bonded with Mizuki.
Afterward, it was revealed by Emperor Azusa, Empresses Funaho and Misaki that the mecha has as its power source, a first generation Jurai Royal Tree seed, with the seed bonding itself with Seina. As a result, Seina is now third-in-line to the Jurai throne, behind Prince Yosho (Tenchi's grandpa) and Tenchi. Thus, a marriage between Seina, Amane, Kiriko, Ryoko, and Neju was arranged for political reasons. Seina is initially very disposed against what he thinks is an attempt to force the girls into marrying him, but is later persuaded otherwise after he learns that they are doing so out of their own free wills.
However, before the ceremony could begin, two incidents occurred. First, Shank broke into Seina's dressing room, hoping to kill the boy. Luckily, Shank's impatience gets the best of him and Seina was able to subdue him. Also, Seto's ladies-in-waiting - Gyokuren, Hakuren, Karen, and Suiren - who were actually agents of the Renza Federation seeking to use Seina's abilities to rid their home from marauding pirates, kidnapped Seina into their small ship, and began to molest him in a public broadcast to ensure their non-Galactic Union organization's survival. As a result, the four are included into the marriage, or at least the crew of the Kamidake II, as it patrols for pirates and illegal activities in space.
Masaki Kajishima (original creator of Tenchi Muyo!) wasn't entirely pleased with the work done on GXP. As such, he began writing the GXP story in novel form. The novels are canon and Seina seems unchanged. The novels follow the story closely with the only exception that the novels go more in depth than the anime.