Undercover High School
Undercover High School (Korean: 언더커버 하이스쿨) is a 2025 South Korean action comedy spy television series written by Im Young-bin, directed by Choi Jung-in, and starring Seo Kang-joon, Jin Ki-joo, and Kim Shin-rok. The series depicts a man who is an NIS agent goes undercover as a high school student. It aired on MBC TV from February 21, to March 29, 2025, every Friday and Saturday at 21:50 (KST). It is also available for streaming on TVING and Wavve in South Korea, and on Viu, Kocowa and Viki in selected regions.
Article
Undercover High School
Undercover High School (Korean: 언더커버 하이스쿨) is a 2025 South Korean action comedy spy television series written by Im Young-bin, directed by Choi Jung-in, and starring Seo Kang-joon, Jin Ki-joo, and Kim Shin-rok. The series depicts a man who is an NIS agent goes undercover as a high school student. It aired on MBC TV from February 21, to March 29, 2025, every Friday and Saturday at 21:50 (KST). It is also available for streaming on TVING and Wavve in South Korea, and on Viu, Kocowa and Viki in selected regions.
Synopsis
Undercover High School
Jeong Hae-seong, a demoted NIS agent following a major incident that occurred during an operation, is tasked with a special mission of tracking down the whereabouts of Emperor Gojong's missing gold bars. Hae-seong hides his identity, goes undercover as a high school student at Byeongmun High School, and meets Oh Su-a, his homeroom teacher. Su-a, a devoted teacher to her students, begins to notice the similarities between Hae-seong and her childhood first love, who left her heartbroken and filled with painful memories.
Cast and characters
Main
• Seo Kang-joon as Jeong Hae-seong / Jeong Si-hyun • Yu Ji-wan as young Jeong Si-hyun
An ace field agent of Domestic Team 4 of the NIS who is given a special mission to find Emperor Gojong's gold bars.
• Jin Ki-joo as Oh Su-a / Oh Bong-ja • Park Seol-ha as young Oh Bong-ja
Hae-seong's homeroom teacher who is a temporary Korean history teacher at Byeongmun High School.
• Kim Shin-rok as Seo Myeong-ju
Chairwoman of the Byeongmun Foundation and Byeongmun High School who is Ye-na's mother.
NIS people
• Jeon Bae-soo as An Seok-ho
Head of the Domestic Team 4 of the NIS and is like a second family and father to Hae-seong.
• Yoon Ga-i as Park Mi-jeong
• Lee Seo-hwan as Kim Hyung-bae
• Im Cheol-hyeong as Gong Jin-sang
Seok-ho's classmate and the head of the NIS Domestic Team 1.
Student Council of Byeongmun High School
Student council president of Byeongmun High School who is Myeong-ju's only daughter.
• Park Se-hyun as An Yu-jeong
Student council member of Byeongmun High School who is Seok-ho's daughter and Hae-seong's younger sister.
• Jang Seong-beom as Park Tae-soo
A student council member of Byeongmun High School who is a son of a three-term National Assembly member from Yeouido.
Student council member of Byeongmun High School who is a son of the CEO of Han Young Law Firm, one of the top law firms in South Korea.
A student council member of Byeongmun High School and an idol trainee.
Student council vice-president of Byeongmun High School.
Students of Byeongmun High School
• Shin Jun-hang as Lee Dong-min
A student of Byungmun High School who is bullied by Tae-soo's group.
One of the class bullies that uses his mouth rather than fists.
• Shin Ga-eun as Choi Su-jin
A student who is faster and more sensitive to SNS and trends than anyone else.
A student of Byeongmun High School who is the source of information and is serious about internet broadcasting and content commercial production.
Teacher's office of Byeongmun High School
• Park Jin-woo as Park Jae-mun
The principal of Byeongmun High School who is Myeong-ju's loyal henchman.
• Oh Yong as Baek Kwang-du,
• Lee Min-ji as Kim Ri-an
Su-a's fellow teacher and soulmate who teaches physical education.
• Noh Jong-hyun as Lee Jun-ho
Su-a's fellow teacher who has a crush on her and teaches mathematics.
Others
• Kim Young-ah as Im Cheong-ha
Su-a's mother who runs Have a Drink With Su-a restaurant for over 10 years.
• Kim Soo-jin as Jang Man-ok
Seok-hi's wife, Yoo-jung's mother, and a mother-like person to Hae-seong.
• Kim Eui-sung as Seo Byeong-mun
A traitor to his nation who was never recorded in history and the keeper of Emperor Gojong's secret safe.
• Oh Eui-shik as Jeong Jae-Hyeon
Hae-seong's father and a NIS agent who was missing for 22 years.
Production
Development
The series began its production and is planned by Namkoong Seong-woo, written by Im Young-bin, directed by Choi Jung-in, and produced by Neo Entertainment and Slingshot Studios. In addition, it aimed to air in early 2025.
Casting
In March 2024, Seo Kang-joon was reportedly in talks as the lead actor and his agency told the media that he was positively reviewing it. This was Seo's first work after completing his military service in May last year as well as comeback to the small screen after 2022 TV series Grid. In May 2024, Jin Ki-joo and Kim Min-ju were reportedly cast to work along Seo with the former as the female lead in the series. In June 2024, MBC confirmed that Seo and Jin would appear as the lead actors for the series. This was also Seo's first MBC drama comeback after appearing in Splendid Politics (2015). The same month, Kim Shin-rok was reportedly confirmed to cast July 2024.
Filming
Principal photography began in the first half of 2024.
Release
Undercover High School
MBC announced that Undercover High School would be broadcast in a Friday–Saturday timeslot in February 2025. The series was confirmed to premiere on MBC TV on February 21, at 21:50 (KST). It is also available for streaming on TVING and Wavve in South Korea, and on Viu, Kocowa and Viki in selected regions.
Viewership
Undercover High School
<table><thead><tr><th rowspan="2">Ep.</th><th rowspan="2">Original broadcast date</th><th colspan="2">Average audience share (Nielsen Korea)</th></tr><tr><th>Nationwide</th><th>Seoul</th></tr></thead><tbody><tr><th>1</th><td>February 21, 2025</td><td>5.6% (12th)</td><td>5.8% (9th)</td></tr><tr><th>2</th><td>February 22, 2025</td><td>6.6% (5th)</td><td>6.5% (4th)</td></tr><tr><th>3</th><td>February 28, 2025</td><td>6.6% (9th)</td><td>6.7% (6th)</td></tr><tr><th>4</th><td>March 1, 2025</td><td>8.3% (3rd)</td><td>8.3% (3rd)</td></tr><tr><th>5</th><td>March 7, 2025</td><td>7.2% (6th)</td><td>7.0% (6th)</td></tr><tr><th>6</th><td>March 8, 2025</td><td>6.7% (3rd)</td><td>7.1% (3rd)</td></tr><tr><th>7</th><td>March 14, 2025</td><td>6.8% (6th)</td><td>6.3% (8th)</td></tr><tr><th>8</th><td>March 15, 2025</td><td>6.1% (4th)</td><td>6.1% (3rd)</td></tr><tr><th>9</th><td>March 21, 2025</td><td>6.1% (7th)</td><td>5.8% (8th)</td></tr><tr><th>10</th><td>March 22, 2025</td><td>5.4% (5th)</td><td>5.3% (5th)</td></tr><tr><th>11</th><td>March 28, 2025</td><td>6.0% (6th)</td><td>6.3% (7th)</td></tr><tr><th>12</th><td>March 29, 2025</td><td>5.8% (4th)</td><td>5.8% (4th)</td></tr><tr><th colspan="2">Average</th><th>6.4%</th><th>6.4%</th></tr><tr><td colspan="5"></td></tr></tbody></table>