The actress transforms from Gyeongseong’s most skilled pickpocket into an undercover interpreter inside the Japanese Government-General in tvN’s new historical spy romance.
Kim Yoo-jung is stepping into enemy territory in the first undercover poster for tvN’s upcoming historical drama 100 Days of Deception.
The newly released image captures her character, Lee Ga-gyeong, after successfully entering the Japanese Government-General of Korea under a false identity.
Surrounded by unfamiliar faces inside the center of colonial authority, Ga-gyeong turns to look behind her. Her guarded expression suggests that even after crossing the building’s threshold, she cannot afford to relax for a moment.
The poster’s tagline reveals the transformation at the heart of the story: “A girl who dreamed of going to America infiltrates the Japanese Government-General.”
That contrast separates Ga-gyeong from the conventional image of a resistance hero. She does not begin the drama with a grand political mission. She is a survivor trying to earn enough money to leave Korea until an offer from the independence movement changes the direction of her life.
From Gyeongseong Pickpocket to Undercover Interpreter
Set during the Japanese colonial period, 100 Days of Deception follows Ga-gyeong, a young woman known as the most skilled pickpocket in Gyeongseong.
Her talent depends on qualities that also make her a promising spy. She can observe strangers, move unnoticed through crowded spaces and judge a person quickly enough to take what she needs without being caught.
Ga-gyeong has been saving money with one goal: reaching the United States and beginning a different life. That plan changes when she receives an offer from Yoo So-ran, a sniper working for the anti-Japanese organization known as the National Salvation Corps.
Played by Kim Hyun-joo, So-ran recruits Ga-gyeong for a mission that will place her inside the Government-General for 100 days.
Ga-gyeong accepts a false identity and gains employment as a trainee interpreter. Every conversation then becomes a potential threat. A mistake in her vocabulary, behavior or personal history could expose not only her identity but also the resistance members who sent her.
Translation Becomes a Weapon
The drama’s most intriguing element may be its use of interpretation as part of the espionage.
An interpreter operates between languages, but also between intentions. The role requires listening to what is said, understanding what is deliberately omitted and deciding how meaning should be carried from one person to another.
Inside the Government-General, that position gives Ga-gyeong access to information that other undercover agents might never hear. Officials may speak freely in front of her while underestimating how much she understands.
It also creates constant moral pressure. A translation can reveal a secret, disguise an intention or alter the outcome of a conversation. In Ga-gyeong’s hands, language could become as important as any physical weapon.
The drama pairs her with Kim Tae-ung, an elite Government-General interpreter played by Park Jin-young. Fluent in three languages, Tae-ung is also connected to a second identity: Sato Hideo, the adopted son of a senior Japanese official.
His history and loyalties remain uncertain, making him especially dangerous to Ga-gyeong. As another professional interpreter, he may be one of the few people capable of recognizing the smallest inconsistency in her disguise.
Their romance will therefore develop in a world where neither person can safely reveal everything they know.
Kim Yoo-jung Takes on a Different Historical Heroine
Kim Yoo-jung has extensive experience in historical dramas, beginning with child roles in productions such as The Moon Embracing the Sun and Dong Yi. She later led the palace romance Love in the Moonlight, playing a young woman who enters the royal court disguised as a male eunuch.
100 Days of Deception also places her character inside a powerful institution under a hidden identity, but the emotional stakes are very different.
Ga-gyeong is not entering a romanticized royal palace. She is infiltrating the administrative center of colonial rule, where discovery could lead to imprisonment, torture or death.
Her background as a pickpocket also gives Kim an opportunity to play a heroine who is quick, mischievous and morally flexible before she becomes involved in the independence movement.
The character’s development will not simply be about completing a dangerous assignment. It will follow a young woman originally focused on escaping Korea as she becomes increasingly connected to the people risking their lives for it.
A Strong Ensemble Surrounds the Central Mission
Alongside Kim Yoo-jung and Park Jin-young, the drama features Kim Hyun-joo, Lee Moo-saeng and Jin Seon-kyu.
Kim Hyun-joo’s Yoo So-ran is the resistance sniper who brings Ga-gyeong into the mission. Her decision to recruit an ordinary pickpocket suggests that the independence group values adaptability and survival instinct as much as conventional training.
Details about the roles played by Lee Moo-saeng and Jin Seon-kyu have not been fully emphasized in the poster announcement, but both actors are known for bringing uncertainty and moral complexity to authority figures. Their presence strengthens the possibility that Ga-gyeong will face threats that cannot be divided neatly into obvious allies and enemies.
The production is directed by Yoo In-shik, whose previous credits include Extraordinary Attorney Woo and the Dr. Romantic series. Kim Yoon-jin is also credited as a director.
The screenplay comes from Ryu Bo-ri, the writer behind Do You Like Brahms?, a drama recognized for its restrained emotional writing and carefully developed relationships.
That combination suggests 100 Days of Deception will balance the urgency of a spy thriller with a slower emotional story about trust, identity and the consequences of concealed feelings.
The Poster Captures the Drama’s Central Fear
The first undercover poster does not show an action sequence, weapon or visible pursuit. Its tension comes entirely from Ga-gyeong’s awareness that someone may be watching her.
That choice reflects the danger of her mission.
She must work inside an institution where an ordinary question about her background could become an interrogation. Every colleague could notice a mistake, while every document or conversation could contain information the resistance urgently needs.
The most dangerous moment may not be entering the Government-General. It may be returning there each day and continuing to behave as though she belongs.
According to the production team, Ga-gyeong’s mission will begin with a life-or-death agreement with the independence movement before escalating into a series of unpredictable developments inside the colonial administration.
When 100 Days of Deception Premieres
100 Days of Deception will premiere on tvN on October 10 at 9:10 p.m. KST and air every Saturday and Sunday.
The series has also been selected for Korea’s AI- and digital-based broadcasting production support program administered through the Korea Communications Commission and the Korea Communications Agency.
With its combination of colonial-era espionage, dangerous translation work and a romance built between two people carrying hidden identities, the drama is positioning itself as more than a conventional historical romance.
For 100 days, Ga-gyeong must lie convincingly enough to survive inside the enemy’s headquarters. But the closer she becomes to Tae-ung, the more difficult it may become to separate the identity she invented from the person she is becoming.