Leon Soryu attends Miyaji Academy as both student council president and captain of the cardfight club. Born into wealth with parents in politics, he carries an ingrained sense of responsibility and leadership. His younger sister Luna, a skilled cardfighter, also studies at Miyaji.

Leon displays a calm, analytical demeanor, approaching cardfights with meticulous strategy and foresight. This mindset initially leads him to view matches as purely tactical contests rather than emotional experiences. He maintains a formal, dignified presence consistent with his status.

A master of the Aqua Force clan, he specializes in multi-attack strategies demanding precise timing. His signature card, "Supreme Heavenly Emperor Dragon, Glory Maelstrom," reflects his commanding style. His deck overwhelms opponents through coordinated assaults and tactical superiority.

Leon’s perspective evolves through encounters with passionate fighters like Chrono Shindou. Their rivalry, particularly during national championship preliminaries, forces him to acknowledge emotion and unpredictable drive beyond calculation. While retaining strategic brilliance, he gradually incorporates passion into his approach.

He shoulders leadership duties with deep commitment, actively strengthening the cardfight club for competitions. This dedication sometimes manifests as high expectations for others—including Luna—rooted in his desire for their growth. Rivalries with fighters like Kamui Katsuragi push him to refine his skills. During the Gyze global crisis, he coordinates efforts and battles to protect the world, demonstrating strategic acumen.

Leon transforms from a purely analytical tactician into a fighter who values heart alongside strategy, without sacrificing intelligence or composure. His relationship with Luna deepens through increased trust and support.