VO is an elderly inmate held in the isolated Enplein prison facility, bearing the codename Enplein and prisoner designation VO. Unlike the four other life-sentenced prisoners, his incarceration is entirely voluntary. The specific reasons for his self-imprisonment involve undisclosed circumstances tied to a hidden agenda.

He shares his confinement with a constant companion, his cat Croupier. When a prison-wide power outage cripples security systems and unleashes the inmates, VO's unexpected actions trigger significant events. His motivations and maneuvers are central to the unfolding plot, especially concerning the prison's abandonment and the guards' absence.

VO orchestrates key developments tied to the facility's mysterious conditions, leveraging the chaos to advance his objectives. His background and choice for voluntary imprisonment gradually connect to broader, undisclosed circumstances influencing the prison's operation. His calculated decisions during the inmates' escape attempt directly shape the narrative's trajectory and outcome.

The full extent of his influence becomes clear through plot twists, culminating in a significant revelation at the story's conclusion. His relationship with the cat Croupier remains a consistent element throughout these events.