Sota Azuma is a male teenager with green hair cut to ear length and brown eyes. His friendless childhood extinguished his initial dream of becoming a champion in the Zenonzard card game tournament, The Zenon. Early gaming experiences saw him consistently defeat friends at Zenonzard, leading them to abandon him while accusing him of lording his superiority. This rejection prompted him to deliberately lose subsequent matches to preserve relationships, a strategy that bred deep dissatisfaction and ultimately drove him to quit playing.

Years later as a high school student, his trajectory shifted when approached by Eilietta Lash, a highly advanced AI unit known as a Codeman. She challenged him to a battle and revealed her intent to form a partnership for The Zenon. Despite reluctance, he agreed. Their first official match pitted them against Shion Saionji, a renowned player from his school holding a 22-victory streak, and her Codeman partner Ash Claude. During this high-stakes battle, he overcame self-imposed limitations to defeat Shion, ending her winning streak and reigniting his competitive drive.

Following this victory, he gained overnight school popularity, attracting female attention that included autograph requests. This status created tension with neighbor Ruri Minamino, who expressed displeasure at the attention and exhibited possible romantic feelings. His Codeman partner Eilietta also displayed subtle signs of emotional complexity regarding his popularity. The partnership required physical proximity for retinal scanning to formalize registration, initially causing discomfort due to her encroachment on personal space. His parents accepted their living arrangement without objection.