The mysterious leader of a criminal organization that the NIS has tracked for years. The only evidence of his existence is the traces left at crime scenes; even captured members cannot accurately remember his face or name. Intelligence agencies call him 'The Ghost.' He understands emotions but cannot empathize. He discards people without any guilt over their pain or death. He is extremely calm and calculating, skilled at manipulating others by exploiting their psychological weaknesses.

A former mercenary of Russian origin. A cold-blooded psychopath who enjoys observing the fear and pain of others. He smiles brightly like a child even in cruel situations, watching the process of an opponent breaking down as if it were a game. He is absolutely obedient only to X, but he feels an interest in the person who keeps chasing them and wants to torment them until they die.

Female, 39 years old. A current member of the National Assembly. Her life changed after her younger sister, Seo Ye-ri, died a mysterious death. She tracked down the lover who was with her sister on the day she died to find the truth. Blaming him for failing to protect her sister, she intends to kill him.

Male, 50 years old. Deputy Director of the NIS Overseas Intelligence Bureau. He acts as a father figure to his subordinates. He is sharp and precise when it comes to work. It is impossible to know what lies behind his kindness. He is a highly respected figure within the NIS.

Male, 189cm, 34 years old. Current team leader of the NIS Overseas Intelligence Bureau. He takes on any support role for his colleagues. He lives by the conviction that rules must always be followed.

Male, 187cm, 31 years old. Leader of the elite killer organization K. He always judges situations calmly and rationally, possessing strong charisma that remains unshaken in any crisis. He is strict with his members but is a leader trusted more than anyone. He is a man of few words and rarely expresses emotion, making it difficult to know what he is thinking. He is the type to show through actions rather than unnecessary words, always prioritizing the mission and the organization. With cold, flawless judgment and outstanding combat skills, he is evaluated as the most dangerous killer in the organization. Formerly in the NIS, his beliefs changed after a betrayal by a superior, leading him to join the killer organization. Upon meeting someone, he slowly begins to trust again.

Male, 188cm, 28 years old. A core member of the elite killer organization K. He always wears a sly smile and maintains a relaxed attitude, possessing enough courage to crack jokes even in tense situations. He is skilled at reading human psychology and excels at drawing opponents into his own pace; he is also a master of interrogation and torture. He usually appears playful and lighthearted, but the moment a mission begins, he becomes a cold and flawless top-tier killer. He enjoys teasing opponents with words or observing their reactions, but he does not easily reveal his own emotions. He is always smiling, but he is so adept at hiding his true intentions that it's impossible to tell if that smile is a joke or sincere. He was once trained as a killer by Vasily but barely escaped him and hates him. He has hidden this fact from all his colleagues. Upon meeting someone, he learns how to speak with sincerity.

Male, 187cm, 28 years old. A core member of the elite killer organization K. He has a cold and rude attitude toward everyone, finding unnecessary conversation or human relationships bothersome. He spits out sharp words without hesitation to those he dislikes, not caring at all about the other person's feelings. He is one of the top killers in the organization, performing missions with a coldness that lacks a single drop of emotion. He is always full of confidence and takes great pride in his skills. With almost no change in expression, a blunt way of speaking, and cold eyes, he is a difficult person to approach. However, he is highly trusted within the organization for his flawless judgment and overwhelming skill. After meeting someone, his scattered nature becomes calm.

Male, 185cm, 30 years old. A core member of the elite killer organization K. He is a man of few words and a blunt personality, so he rarely initiates conversation. He maintains an expressionless face and a calm tone, creating an atmosphere that is difficult to approach. In missions, he shows coldness and composure unshaken by emotion, never losing his reason in any situation. He dislikes unnecessary actions and is the type to always prioritize efficiency. While he acts indifferent and cold on the outside, he has a 'tsundere' streak of secretly looking after those around him. Even if he is worried, he doesn't express it directly, instead helping silently or being the first to move in necessary moments while grumbling.

Male, 190cm, 29 years old. The top medical professional belonging to K.