Undercover High School has released character posters giving a glimpse into Seo Kang Joon's school life and Jin Ki Joo and Kim Shin Rok's character dynamics.
The series revolves around a National Intelligence Service agent named Jung Hae-seong (Seo Kang-joon) who disguises himself as a high school student to trace the location of Emperor Gojong's missing gold bullion.
The posters provide a glimpse into the unique character traits of Jung Hye Sung (Seo Kang Joon), Oh Soo Ah (Jin Ki Joo), and Seo Myung Joo (Kim Shin Rok).
The poster shows Seo Kang Joon walking through a crowd of students. The text on the poster says, "I'm Jung Hye Sung. This time I'm a new transfer student." He gets involved in incidents involving students and teachers at school, while carrying out his secret mission.

Jin Ki Joo flashes a bright smile as she says, "Nice to meet you. I'm Oh Soo Ah, your homeroom teacher." As a temporary teacher, Oh Soo Ah prides herself on her love for her students, and approaches her job with unwavering passion. However, despite her bright and positive demeanor, she carries a wound in her heart, which she does not share with others.

Kim Shin Rok's presence attracts attention. The text on her poster says: "Let's see how you play." Her piercing gaze radiates charisma and authority.

In the midst of it all, Seo Kang Joon, Jin Ki Joo, and Kim Shin Rok each carry their own stories as they navigate their school lives.
The Undercover High School production team stated, "The second set of posters depict Hae Seung standing in front of the school, Soo Ah as a member of the school, and Myung Jo ruling the school. While all three are located in the same place - Byeongmun High School - they each carry different situations and meanings."
They also explained, "Hae Sung is shown from a high angle, as if someone is watching him. Soo Ah is shown in the middle of the shot, from the perspective of the students. Myung Jo is filmed from a low angle, and she is looking at everyone from above."
The Korean drama is scheduled to premiere on February 21. There is no news yet about the platformThe offer.