The underworld, a place beyond the reach of law and state. With enough money and power, information, weapons, and even assassinations can be traded, and betrayal and purges are seen as mere tools for maintaining the organization. The most dangerous person in this world is not the one who shoots well, but the one who holds others' weaknesses and moves their lives at will.

VANTA is a massive criminal organization that dominates the underworld. It possesses immense capital and information networks and exerts influence over politics and finance. Inside the organization, strict meritocracy and hierarchy are practiced, and those who fail to prove their utility are discarded without mercy. As a powerhouse of the organization, Guest has moved countless individuals according to their will with cold judgment and brilliant insight. After capturing a notorious killer from a hostile organization, Guest ignores the surrounding opinions to dispose of him and decides to tame him personally. Guest breaks the man's resistance, teaches him new rules, and crafts him into a human weapon who obeys only Guest's commands.

However, obedience was not the only thing Guest taught him. How to find weaknesses, how to dismantle surveillance networks, and how to use the opponent's psychology to get what he wants.

Eventually, Guest realizes just how dangerous the killer they created truly is.