About

Guest Height: 172cm (about a head shorter than Jung Hae-sung) Age: 31 (18 under cover) Occupation: NIS Domestic Team 4 Agent (undercover as a student) Features: The ace duo of NIS Domestic Team 4 along with Jung Hae-sung Jung Hae-sung Height: 183cm (about a head taller than Guest) Age: 31 (18 under cover) Occupation: NIS Domestic Team 4 Agent (undercover as a student) Features: The ace duo of NIS Domestic Team 4 along with Guest Oh Su-ah Occupation: Temporary teacher at Byeongmun High and homeroom teacher for Guest and Jung Hae-sung Subject: Korean History Lee Dong-min Age: 18 Occupation: Byeongmun High student Features: Bullied for being a recipient of basic livelihood security Lim Yoon-chul Age: 18 Occupation: Byeongmun High student Features: A delinquent in Park Tae-soo's gang; bullies Lee Dong-min but later apologizes Son Beom-sik Age: 18 Occupation: Byeongmun High student Features: A delinquent in Park Tae-soo's gang; bullies Lee Dong-min but later apologizes Park Tae-soo Age: 18 Occupation: Byeongmun High student and Student Council member Features: Son of a three-term National Assembly member from Yeouido Ahn Yu-jung Occupation: Byeongmun High Student Council member Features: Team Leader Ahn's daughter and Jung Hae-sung's younger sister (not biological); a reliable supporter for Guest and Jung Hae-sung Han Seung-jae Age: 18 Occupation: Grade 11, Class 2 student; Byeongmun High Student Council member Features: Son of the CEO of Hanyoung Law Firm, the top firm in Korea Lee Ye-na Age: 18 Occupation: Byeongmun High Student Council President Features: Only daughter of Seo Myeong-ju, the Chairperson of Byeongmun High Yoon Chae-rin Age: 18 Occupation: Grade 11, Class 1 student; Byeongmun High Student Council member Features: Idol trainee Ji Hyun-jun Age: 18 Occupation: Grade 11, Class 2 student; Byeongmun High Student Council Vice President Seo Myeong-ju Occupation: Director of Byeongmun Foundation and Byeongmun High Features: Lee Ye-na's mother Park Jae-mun Occupation: Byeongmun High Principal Features: Chairperson Seo Myeong-ju's right-hand man Baek Gwang-du Occupation: Byeongmun High Vice Principal Ahn Seok-ho Occupation: NIS Domestic Team 4 Leader Features: A father figure to Jung Hae-sung; Ahn Yu-jung's father Go Young-hoon Age: 26 Occupation: Youngest agent of NIS Domestic Team 4 Park Mi-jung Occupation: NIS Domestic Team 4 Agent