Leon Sōryū hails from the Soryu family, former rulers of the seas through their bond with Planet Cray's Aqua Force clan. After Aqua Force's mysterious disappearance, the family lost power, stranding Leon, his childhood friends Jillian Chen and Sharlene Chen, and their chieftain on a remote island. Driven to restore his clan, Leon struck a pact with the entity Void. In exchange for PSY Qualia, he agreed to aid Void's plan to erase Royal Paladin, Shadow Paladin, and Kagero by capturing their leaders Blaster Blade, Blaster Dark, and Dragonic Overlord. This alliance positioned Leon with antagonistic forces during the Asia Circuit arc. Leading Team Dreadnought alongside Jillian and Sharlene, Leon competed in the Vanguard Fight Asia Circuit to sabotage efforts to rescue Cray's lost clans. His manipulations culminated in a confrontation within the subspace between Earth and Cray. There, he defeated Toshiki Kai but was ultimately bested by Aichi Sendou. This defeat shattered Void's influence, freeing Leon to assist Aichi in rescuing the captured leaders and restoring balance. Though Takuto Tatsunagi revoked his PSY Qualia, Leon retained his innate ability to sense and command wind, confirming his bloodline's rekindled bond with Aqua Force. Leon subsequently transitioned into an ally. During the Link Joker invasion, he encountered Reversed fighters and confronted a corrupted future version of himself, embodying his internal struggle. Overcoming this manifestation through his bonds with allies marked his full atonement. His development emphasized valuing companionship over solitary ambition, notably mentoring Naoki Ishida in season 4 by training him on the Soryu island and entrusting him with Aichi's well-being. Leon later appeared in the G series as Aqua Force Clan Master in Magallanica, guiding new fighters like Jaime Alcaraz and Chrono Shindou. His commitment to expanding Aqua Force's global influence remained a driving motivation. Leon's cardfighting centered on Aqua Force, utilizing units like Blue Storm Dragon, Maelstrom and later Blue Storm Supreme Dragon, Glory Maelstrom. His strategies relied on precise attack sequencing to activate skills such as rearguard-standing and retirement effects, often forming high-power columns. Deck adaptations reflected his growth, shifting from versatile setups to critical-focused builds featuring Glory Maelstrom's Ultimate Break, which restricted defensive options. Physically, Leon typically wore formal attire with blue-and-white motifs, symbolizing his clan. In the V Series timeline, he appeared younger, donning a blue jacket with gold accents while retaining his blond hair and purple eyes. His calm, analytical demeanor persisted, though he evolved from aloofness to approachability, particularly in mentoring roles. His signature wind manipulation ability, initially conflated with PSY Qualia, was later clarified as a hereditary trait distinct from Void's influence.