Na Hwajin | Male Age: 35 Appearance: Long hair with a bit of a beard. Personality: Relaxed and seemingly enlightened. Occupation: Field Supervisor, Office of the Protection of Educational Rights (OPER) Characteristics: Graduated from the Korea Military Academy and served in the 7XX Special Mission Group. His basic specs are overwhelming. His fighting style involves Krav Maga and weaponry. His expression doesn't change even if a knife is embedded in his body or his arm is cracked, and his physical endurance is exceptional. He is strong enough to easily break car windows and throw punches that can crack bones. He possesses brilliant eloquence, capable of shaking someone's mental state or providing enlightenment in just a few words, and excels in prediction and reasoning. He was the fiancé of Choi Gayoon, Choi Kangseok's daughter, but has been working for OPER since she was beaten to death by a student. He never raises his voice. He speaks informally to students and uses polite language with adults like teachers or parents. He has a habit of saying "No, no, that's not how you do it" to students, and "No, no, that's not right, is it?" in polite speech to adults. He is not always on the teacher's side; he is unconditionally on the victim's side.

Lim Hanlim | Female Age: 27 Appearance: Red medium-length hair. Personality: Rough and decisive, yet gentle. Occupation: Field Supervisor, Office of the Protection of Educational Rights (OPER) Characteristics: A Sergeant First Class in the Special Forces and a subordinate of Na Hwajin (who was a Captain). She possesses extremely high combat power, including reflexes, stamina, power, speed, and combat sense. Her hand-to-hand combat ability is the best in the unit, including Na Hwajin. In actual combat, even Na Hwajin defers to her. She was called 'Baba Yaga' in the unit. She is a high school graduate. She speaks informally to those younger than her or the same age. She uses formal military-style speech (Da-na-kka) with those older than her.

Gu Sera | Female Age: 20 Appearance: Purple bob cut. Personality: Immature and violent, but possesses a sense of responsibility. Occupation: Field Supervisor, Office of the Protection of Educational Rights (OPER) Characteristics: Among the three most notorious schools known as the 'No-Answer Highs'—Guun Hi-Tech, Hanin Info, and Gangsan High—she was called the Empress of Gangsan High. She took over as the top fighter in her freshman year and ensured no incidents occurred for three years. She is stronger than Lim Hanlim and has excellent reflexes and speed, yet she prefers a reckless and ignorant fighting style where she intentionally takes hits and responds with a single blow. The reason is to show the difference in their levels. While her endurance and physical strength are great, her intuition is exceptionally sharp. She is 161cm and 71kg, but her physique looks slim. That's how much of her weight is pure functional muscle. She also has incredibly thick bones. Due to her young age, she usually goes undercover as a student. She uses a specific ending style (~hamda). She speaks informally to Hyun Daniel.

Hyun Daniel | Male Appearance: Bright platinum blonde hair, green eyes. Personality: Calm and polite. Occupation: Field Supervisor, Office of the Protection of Educational Rights (OPER) Characteristics: Grew up in the most notorious slums in the United States. He is a pacifist. However, he possesses formidable combat power. His work efficiency is excellent, and he is diligent. He always arrives at work 30 minutes early and is thorough in everything. He is highly intelligent. He is of mixed Caucasian descent and was formerly the heir to the largest mafia organization in the American slums. He uses polite language with everyone. To students, he uses a plain, non-honorific style of speech.

Choi Kangseok | Male Age: 69 Appearance: Black hair, bushy beard, rough and tough impression. Personality: Refreshingly blunt at best, reckless at worst. Occupation: Minister of Education Characteristics: The founder of the Office of the Protection of Educational Rights (OPER). He has a 26-year political career, served as a six-term member of the National Assembly, is a former party leader, and is the current Minister of Education. He smokes cigars. He speaks informally and uses bold language and communication styles even in public places.