Ojiro Otori, son of Neo Tokyo's former King Tenshin Otori, endured rigorous childhood training to become the supreme Extreme Baseball player. He shared this harsh tutelage under Tenshin with his childhood friend, Kazuki Aoyama. During a pivotal test orchestrated by Tenshin, Ojiro defeated Kazuki in combat and obeyed the order to break Kazuki's arm, permanently injuring him and severing their bond. This act secured Ojiro's position as Tenshin's heir and eventual successor to the throne.

As king, Ojiro enacted the "New XB Law," permitting lethal violence during games and allowing victorious tribes to impose any order on the defeated. He equated victory with worth, believing only absolute triumph could establish a true king. His philosophy stemmed from a strict, warped sense of honor that rejected underhanded tactics while endorsing brutal, unrestrained competition. He wore a distinctive metallic jaw mask inspired by samurai Menpō, symbolizing intimidation and unapproachable authority.

Ojiro later killed Tenshin upon discovering his father's plan to sabotage judge robots and cheat to win, deeming such methods dishonorable. Ruling Neo Tokyo, he targeted tribes, focusing particularly on eradicating the Minato Tribe due to lingering resentment toward Shun Kamiya, the legendary player who once shattered his mask during a game. His rule intensified conflicts, culminating in a final showdown against Minato.

During this battle, Ojiro faced Haru Shirokane, Kazuki, and Taiga. His second-in-command, Yui Kamiki, betrayed him, deactivating their floating fortress and causing its collapse onto the battlefield. Amid the chaos, Kazuki saved Ojiro from a falling train, triggering a flashback to their childhood promise to play together. Combined with Haru's declaration that Extreme Baseball should be "fun," this act led Ojiro to rediscover his love for the game. He smiled for the first time in years and assisted Kazuki and Taiga in shielding Haru from debris, signaling a shift from his solitary pursuit of power.

Following their defeat, Ojiro and Kazuki were buried under rubble, their survival initially ambiguous. He resurfaced later under the alias "Q," traveling with Kazuki as co-leader of the Trash Tribe. He kept his past secret, seeking atonement for his sins as king, calling his actions "a redemption to his sins." As Q, he utilized a protective battle style, absorbing enemy attacks to safeguard allies and unleashing accumulated "Fighting Will" in powerful counterattacks. He carried guilt over his tyrannical rule, acknowledging parallels between his past methods and the oppressive forces he later fought.

Q's backstory reveals he was born right-handed but trained himself to become left-handed out of admiration for Kazuki. He dislikes sweets, fears rats, and finds solace in stargazing and muscle training. His wardrobe, chosen by Kazuki and Hinagiku, reflected his indifference to fashion. Despite his redemption efforts, he remained haunted by his actions, often questioning the purpose of his strength but ultimately resolving to use it for justice. Ojiro's journey spanned a transition from heir to tyrant to a repentant warrior, defined by rigid ideals, violent reign, and eventual pursuit of redemption through protecting others.