Yūga Ohta is a college student driven by a hustler mentality, relentlessly pursuing money and high-stakes thrills. He first entered the world of the Slave Control Method (SCM) by distributing the devices alongside his partner in crime, Shinnosuke Tachikawa. This led him directly into the underground SCM slave-trading game. Within this arena, Yūga sought out other users, aiming to defeat them in strategic battles of wits to claim them as his slaves. He recruited Eia Arakawa as an accomplice, leveraging her perceptive abilities to manipulate opponents and expand his network of controlled individuals.

Yūga's participation became marked by an escalating obsession with the thrill of domination and the SCM's inherent power dynamics. This obsession drove him to take increasingly extreme risks. During one confrontation, he was outmaneuvered by Ryuuou Edogawa, becoming Ryuuou's slave. He regained his freedom when Ryuuou dispatched him to duel an unknown SCM user – later revealed as Eia Arakawa in disguise. Eia defeated Yūga in this pivotal duel, making him her slave. This outcome fundamentally shifted their relationship from partners to adversaries within the SCM hierarchy.

Yūga's trajectory depicts a descent into moral ambiguity fueled by his fixation on the SCM's power. His initial portrayal as a thrill-seeking opportunist evolved into that of a manipulative and ruthless figure, willing to exploit others for personal gain. The consequences of his actions culminated in his own enslavement, highlighting the cyclical nature of control and subjugation within the SCM system. His strategic mindset and consistent willingness to employ psychological manipulation defined his character arc even as his circumstances underwent dramatic shifts.