TV-Series
Description
Jūjirō Oni, a third-year at Okayama Oku High School, serves as a key competitor for Japan's U-17 World Cup team. Originally placed in the U-17 Camp's 5th Court, he deliberately stayed in lower courts to strengthen other players, earning the moniker "The Gatekeeper from Hell." This strategy reflected his goal to elevate Japan's overall tennis strength, despite possessing skills rivaling the camp's top-ranked players.

Standing 187 cm tall with a muscular build, Oni possesses distinctive long, dark red hair and noticeably jagged canine teeth, contributing to his rugged, intimidating presence. Off the court, he reveals a softer side, particularly around children. His drive to become Japan's top player originated from promises made to orphans he frequently visited, aiming to see their happy reactions to his success.

Oni joined the U-17 Camp two years prior as a first-year. He engaged in a fierce match against future captain Byoudouin Houou, achieving the Kishin (Ogre God) state to return Byoudouin's powerful shots. Oni won 7-6, leaving Byoudouin with a scar from a ball strike. He then maintained an undefeated streak as Japan's top player for a year before voluntarily stepping down to mentor others.

At the camp, Oni enforced strict standards, expelling high schoolers who lost to middle schoolers in initial tie-breaks. His first on-screen match was a 6-0 victory against Momoshiro Takeshi, where he used a racket with only two strings to demonstrate devastating power. He later initiated a Team Shuffle match after middle schoolers dominated the 5th Court. With the match tied, Oni substituted himself into the deciding game, defeating Takei Toshio 6-0 and securing the 5th Court's promotion to the 3rd Court.

Oni's original position as Japan's No. 5 representative was later confirmed. He reclaimed this rank by defeating Kazena Kaji, who had held the spot during Oni's absence from international play. During the "Genius 10 Challenge," he faced Kintarō Toyama in a badge match. Despite Toyama's initial lead and improved abilities, Oni won the first set 6-3 after accessing his full power for the first time since becoming the Gatekeeper. The intense match pushed both to achieve the "Pinnacle of Perfection," with Oni ultimately prevailing.

At the U-17 World Cup semifinals against Germany, Oni played Singles 1 against Jürgen Borisovich Volk. He secured a comeback victory (4-6, 7-6, 7-6), advancing Japan to the finals and highlighting his role as the team's decisive closer.

An all-rounder with a dominant right arm, Oni wields the FISHCER MAGNETIC TOUR 100% racket and wears Head Adapt 1105t shoes. His playstyle overwhelms opponents through sheer power and relentless pressure, often culminating in the Kishin transformation during critical matches. This state enhances his shot precision and force, enabling returns of advanced techniques like Byoudouin's.