Tennan, Seriyou

天南静竜

When Juraian Emperor Azusa visits Earth and attempts to bring his daughters Ayeka and Sasami back home, they refuse, wanting to stay with Tenchi. Still resentful that Tenchi's grandfather (and the emperor's own son) Yōshō abandoned Jurai to marry an Earthling, Azusa reluctantly agrees, but only if Tenchi can defeat his chosen fiancé for Ayeka in a duel. This "worthy suitor" is Seiryō Tennan, son of one of Jurai's wealthiest families. Flashy and possessing an exaggerated sense of style (he rigs his own light show and cherry blossoms for special effects), Seiryō views the situation from a skewed perspective, believing the princesses are confined in a dump worse than a prison cell. He takes it upon himself to "liberate" Ayeka from forced labor and the barbarous Tenchi, considering it his, or rather, "any civilized person's" moral duty.
Boastful, Seiryō thinks it would be wise for Tenchi to concede—not wanting to "bully the weak"—and begs him not to worry, claiming he won't use his full power. Some time before the duel is set to begin, the group makes predictions on who will win: the majority side with Tenchi, Azusa favors Seiryō in "less than a minute", and Washū places an unorthodox bet on Mihoshi.
It turns out Washū was unusually perceptive. Mihoshi's shuttle crash-lands in the Masaki family lake before the match begins, swamping the deck of the house and leaving a dazed Seiryō to be washed back into the water. As a result, Tenchi wins by default, and Seiryō loses his chance at an arranged marriage.
His "defeat" is so humiliating for Seiryō that he develops a personal hatred for all Earthlings, a grudge that continues into Tenchi Muyō! GXP. He holds a teaching position at the Galaxy Police Academy and immediately develops a distaste for the human Seina Yamada when he becomes a cadet.
Seina becomes Seiryō's nemesis, constantly foiling his endless idiotic plots for revenge (mostly through Seina's streak of bad luck). Having rebounded from his missed shot at Ayeka, Seiryō becomes infatuated again with childhood acquaintance Amane, despite being frequently and violently rejected; her attachment to Seina only deepens his hatred for the young captain, so much so that in Episode 6, Seiryō withholds the necessary body augmentation that Seina needs to at least survive life at the academy. However, Mikami Kuramitsu finds out and assigns Seiryō to clean toilets... with her niece Mitoto supervising. Seiryō is brash and overconfident, often severely embarrassing himself through acts of sheer incompetence. However, he is also an accomplished fighter and is quite proficient with a lightsword.
After Amane allows him to be captured by the enemy in Episode 9, Seiryō learns in Episode 18 that the Daluma pirate guild has signed a supply contract with the Tennan family. Seiryō follows his father's orders to assist the pirates and becomes the captain of the Daluma guild's anti-Seina Good Luck Fleet. In a stunning display of idiocy, he names his flagship Unko, which could mean "Luck Bringer" in Japanese... but also translates as "poop".
After fighting the G.P. ship Kamidake II to a standstill twice, Seiryō then challenges Seina to an official duel. However, during the duel, Seina trips on a piece of candy and pulls off Seiryō's belt, exposing his red bikini briefs and costing Seiryō another match by embarrassment.
At the end of the series, Seiryō works as the head waiter at a space station behind Earth's moon, where Seina's wedding is being held, as the station is owned by the Tennan family. While there, he encounters space pirate and former captor Kyō Komachi, and proposes to her after revealing that it is her birthday.