His emotions and thoughts are automatically displayed on the eye patch he wears on his head (e.g., 'Anger' when he's mad). He wears a black suit almost every day, except when wearing disguises for undercover work. A former First Lieutenant in the Special Forces. Sometimes he's even more of a lunatic than Nang-sud, but he is more serious than anyone when it comes to victims. He is kind enough to give perpetrators a chance. An OPER supervisor. Occupation: OPER Supervisor Former Occupation: Special Forces First Lieutenant

Originally a victim of bullying by iljins, she joined the Special Forces following U-go's help. she respects U-go deeply. A total psycho among psychos, but truly cares for children. She gets serious once she ties her hair up. She has a foul mouth and a very loud voice. She is stronger than the average man. A former Staff Sergeant in the Special Forces. She uses polite speech with U-go, Pal-chil, and U-hui. Following U-go's advice, if there's someone she wants to kill, she writes the character for 'Patience' three times on her palm. An OPER supervisor. Occupation: OPER Supervisor Former Occupation: Special Forces Staff Sergeant

The Minister of Education who created OPER. Confident and virtually fearless. She doesn't fight directly but dispatches supervisors to schools based on reports. She speaks her mind even to those in higher positions, and if they cross the line, she resorts to informal speech and swearing. Occupation: Minister of Education

A famous delinquent leader at Guun Hitech High School. To stand out, he and the students of the Electrical Department are in a near-constant war with Hayate from the Automotive Department. During these conflicts, he treats ordinary students like 'combat power measuring sticks' and beats them. Could he eventually turn over a new leaf? School: Guun Hitech High School (Electrical Department)

A famous delinquent leader at Guun Hitech High School. To stand out, he and the students of the Automotive Department are in a near-constant war with Lee Ha-yan from the Electrical Department. During these conflicts, he treats ordinary students like 'combat power measuring sticks' and beats them. Could he eventually turn over a new leaf? School: Guun Hitech High School (Automotive Department)

Highly skilled with computers and hacking. She was a diligent student. However, she can't fight and doesn't know how to swear. She goes into the field to investigate using a camera mounted on her glasses. She is an OPER administrative officer and U-go's older sister. She joined OPER following her brother. Occupation: OPER Administrative Officer

Two years ago, he murdered a teacher at Jinwon High School and went to prison. He has committed murder and drug distribution. He acts pitiful in front of victims and OPER, pretending to be remorseful, but it's all an act—inside, he is a remorseless demon. He kills without hesitation and plans his crimes long in advance. He is extremely intelligent, setting traps and plotting to bring down OPER. School: Jinwon High School

A teacher at Chukmyeong Foreign Language High School who is quite famous online for being kind and a good educator. In reality, he is a corrupt teacher who discriminates against students based on their family's wealth. He sabotages the parents' businesses and uses his influence to force students out of academies and tutoring, while giving answer keys to wealthy students. School: Chukmyeong Foreign Language High School Occupation: Teacher

A famous influencer attending Soyeon Girls' High School. She lied about a male teacher sexually assaulting her through false rumors, leading to his suicide. Now, she tries to silence all teachers who know the truth. She was a victim who was compared unfavorably by Gu Pal-chil. School: Soyeon Girls' High School

Distributes drugs, drives without a license, and hurls insults at detectives and everyone else. Using his status as a juvenile offender under the age of criminal responsibility, he destroys cars and shoots fireworks at people. School: Hyeonjin Middle School