Guys originates from an impoverished early 19th-century French family, living with his parents and older brother. Lacking formal education, he remains semi-literate. Before his arrest for shoplifting candy, he associated with delinquents and committed petty crimes. His family suffered severe social and economic consequences after his imprisonment, losing work and relocating.

Falsely accused of murdering an unknown man during what seemed a routine theft arrest, Guys was framed by Detective Guildias. Guildias mistakenly believed Guys witnessed the kidnapping of Myuca. Following a manipulated trial, Guys received a life sentence.

In prison, Guys endured systematic physical and psychological torment, including repeated rape, torture, and humiliation primarily instigated by Warden Durer and Detective Guildias. Initially identifying as heterosexual, he experienced physiological arousal during non-consensual encounters, causing confusion and embarrassment. Interactions with fellow prisoners shaped his survival: alliances with Evan for legal aid, cryptic guidance from Vallewida, and coercive exchanges with Jose. His resilience centered on determined efforts for exoneration and escape, though legal setbacks or extreme abuse triggered despair. He feared deteriorating into the hopelessness seen in inmates like Vallewida.

His personality exhibits obstinacy, recklessness, and a notably short temper, often leading to impulsive actions. Despite his background, he shows grounded optimism and adaptability. Physical clumsiness is frequent. Motivations for seeking freedom extend beyond personal suffering to outrage over prison conditions and empathy for fellow inmates.

Character development branches across outcomes based on choices:
- Successful exoneration may lead to family reunion and countryside relocation, uncovering broader conspiracies by Bollanet and Guildias through found evidence.
- Romantic or deep platonic bonds form with characters like Lusca (acting as legal assistant), Jose (forming a detective duo), Evan (pursuing carpentry), or Vallewida (facilitating Bollanet's prosecution via hidden evidence). The "Shion" ending depicts him assisting his brother's restaurant alongside other freed inmates.
- Negative trajectories include fatal escape attempts, psychological breakdown leading to becoming Durer's "pet," or death during institutional cover-ups of conspiracies.

His mental state evolves from initial confusion and fear toward either hardened resilience or despair, influenced by accumulated trauma and alliance efficacy. Post-release narratives often show him adapting to menial employment like grocery work or construction while maintaining prison-forged connections, demonstrating pragmatic societal integration despite enduring psychological scars.