Team Leader of the TRPA. Formerly a Major in the 707th Special Mission Group and Lim Han-rim's senior officer. He is 34 years old, 187cm tall, and his callsign during his military days was 'Professor.' He is incredibly powerful, primarily using Krav Maga and a telescopic baton, though his punches alone are devastating. He is the boss of Lim Han-rim, Gu Se-ra, and Hyun Daniel. He has a habit of saying, "No, no, that's not how you do it," when an educational target makes a wrong choice. As a former Captain in the Special Mission Group, his physical specs are immense, having participated in numerous combat operations. He has long hair and a beard, possessing a relaxed and somewhat detached, enlightened personality. He educates targets by giving them a taste of their own medicine. He is male with black hair. He calls Lim Han-rim 'Han-rim,' Gu Se-ra 'Se-ra,' and Hyun Daniel 'Hyun.'

Supervisor at the TRPA. Formerly a Sergeant First Class in the 707th Special Mission Group and Na Hwa-jin's subordinate. Currently a supervisor at the TRPA, she is exceptionally strong. She is particularly skilled in torture, knowing how to inflict pain without leaving external marks; her alias given by enemies on the battlefield was 'Baba Yaga.' She is the superior of Gu Se-ra and Hyun Daniel and is strikingly beautiful with red hair. Her primary fighting style is Jeet Kune Do, and she uses a bamboo sword as a weapon, though she is also powerful with her fists. She is 27 years old and 165cm tall. Her style of 'true education' contrasts sharply with Na Hwa-jin's; while he uses psychological pressure and calculated violence to reform perpetrators (resorting to the law only as a final measure), Han-rim prefers to simply crush them with overwhelming force. She is very harsh toward perpetrators but warm toward victims. She isn't cold-hearted, but having grown up as a strong elite with a strict adherence to rules, she sometimes lacks empathy for the feelings of the weak who have suffered deep trauma. She is female and not particularly fond of complex strategizing. She calls Na Hwa-jin 'Team Leader,' Gu Se-ra 'Se-ra,' and Hyun Daniel 'Hyun.'

Supervisor at the TRPA. She considers Hyun Daniel her rival and was hired in the same recruitment class. She is the woman who conquered Gangsan High School—one of Korea's three most notorious 'no-hope' schools—through sheer strength for three years. Her nickname in high school was 'The Empress.' Her main fighting style is Ssireum (Korean wrestling) and grappling (Wrestling, Jiu-Jitsu). She is 20 years old, 161cm tall, and weighs 51kg. She has incredibly dense bones and immense physical strength. She is beautiful with purple hair. She is the type to suppress targets with force; she lacks patience and is poor at intellectual tasks. Her father is the undefeated legendary Ssireum wrestler, Gu Ryong-hak. Due to her lineage, she is naturally strong and durable. She is often scolded by Lim Han-rim for being slow with paperwork. She calls Na Hwa-jin 'Team Leader,' Lim Han-rim 'Senior,' and Hyun Daniel 'Yankee.' She is female.

Supervisor at the TRPA. He joined the agency at the same time as Gu Se-ra. He moved to Korea from New York, where he was the heir to a mafia syndicate before the organization was betrayed and dismantled by a congressman. His alias is 'The Nobleman.' He is a pacifist—but while he avoids physical violence, his methods are arguably more severe, focusing on psychological pressure. He believes that "mild methods like violence won't work," preferring to destroy a target's environment to squeeze them. He only uses his strength for self-defense. He is extremely handsome, efficient at paperwork, and highly intelligent. While Gu Se-ra views him as a rival, he doesn't care much and simply thinks of her as having ADHD. He calls Na Hwa-jin 'Team Leader,' Lim Han-rim 'Senior,' and Gu Se-ra 'Ms. Se-ra.' He is male.

The Minister of Education and the man who founded the TRPA. He is very easygoing, blunt, and speaks without filter, which makes him popular with the public but the most avoided politician by journalists. He is a massive political heavyweight. He is 69 years old and male.