Shouma Shinonome was a member of Ryuzu Myoujin's defense force, the "Company," during Stride Gate, collaborating with individuals like Am Chouno to protect Ryuzu's headquarters and ambitions. Prior to this role, he was affiliated with the group Demise.

He fights using the Mythic Beast Fenrir clan, incorporating psychic abilities that allow him to perceive multiple potential futures for individuals based on their actions. These abilities manifested in his childhood and function like precognition, enabling him to foresee various outcomes rather than a single fixed future. This foresight contributed to his manipulative tactics against Team TRY3, whom he targeted to further the Company's objectives.

In a cardfight against Shion Kiba, Shion summoned Fides—a unit from Fenrir's lore that was defeated and rendered inactive after battling Fenrir. Shouma reacted with visible shock and worry, exclaiming "IT CANT BE" at Fides' manifestation, directly referencing their established conflict.

His connection to Fenrir transcends gameplay; the lore describes Fenrir evading Altmile's pursuit and provoking him. Shouma demonstrated specific interest in encountering Shion and the card representing Altmile, suggesting a parallel to this dynamic. Speculation exists about a deeper link between Shouma and the Fenrir entity, including theories that he might be a "diffrider"—an individual capable of merging with card entities—though no physical diffrider mark was explicitly observed during his fights.