Kim Yoo-jung Goes Undercover in tvN's Colonial Spy Drama 100 Days of Lies

Kim Yoo-jung's first teaser for 100 Days of Lies landed on the 29th, and the response was immediate: viewers flooded the comments with variations of the same thought, that she only gets better with each project. The clip marks an early signal of interest for a drama that, even before its October 10 premiere on tvN, is drawing the kind of attention that usually comes later in a run.

The series is set in 1930s Gyeongseong (colonial-era Seoul) and follows a spy romance that unfolds over one hundred days inside one of the era's most surveilled institutions. What gives the concept some structural tension is the framing: the undercover agent at the center of the story is not a trained operative but a street-level pickpocket, dragged into espionage by circumstance and a promise of passage to America.

The story

Kim Yoo-jung plays Lee Ga-kyung, who works the crowds at Gyeongseong Station with considerable skill. Her sole ambition is saving enough money to emigrate to the United States. That plan shifts when a woman she tried to rob, Yoo So-ran (Kim Hyun-joo), a sharpshooter for an independence resistance group, offers her a deal: a ticket to America in exchange for infiltrating the Government-General. The teaser catches the moment Lee Ga-kyung hears the offer and responds, visibly shaken: "You're telling me to become a spy?"

She takes the deal. Inside the Government-General, she assumes a false identity as an interpreter named Geum Seo-hee, and almost immediately draws the suspicion of Sato Hideo (Park Jin-young), the office's newly arrived senior interpreter. What the series promises to complicate is the fact that Sato Hideo has a second identity of his own, his Korean name is Kim Tae-woong, and he is returning to Korea for the first time in over a decade after being adopted into a Japanese official's family.

The cast and production team

The ensemble is built around that central tension. Kim Hyun-joo's Yoo So-ran carries both a nationalist mission and a private grudge, while Lee Moo-saeng plays Yu Philip, a Gyeongseong-based foreign correspondent of Korean-American background who is applying pressure on a senior colonial official. Jin Seon-kyu rounds out the leading cast as Sato Shin-ichi, the Government-General's second-in-command and the resistance group's primary target, a character described as someone who will use any means available to advance his position. Lee Gi-young, Choi Deok-moon, Seo Jeong-yeon, Kim Do-hyun, and Kim In-kwon fill out the supporting roles.

The script is by Ryu Bo-ri, who previously wrote Do You Like Brahms? and Trolley, both of which were noted for their careful attention to characters' emotional interiors. The director is Yoo In-sik, whose track record in this genre is difficult to argue with. His Romantic Doctor Kim Sabu franchise peaked at 27.6% ratings in its first season and 27.1% in its second, with a third season still managing 16.8%, figures that are exceptional for cable television in Korea. Extraordinary Attorney Woo, which he also directed, opened below 1% on a relatively new channel and finished at 17.5%, becoming one of the more discussed Korean dramas of recent years internationally.

The production has also been selected for an AI and digital production support program run by the Korea Communications Commission and the Korea Radio Promotion Association, a government initiative that funds select broadcast projects exploring AI-assisted production methods.

Before the premiere

The cast observed a moment of silence for independence movement figures at a script reading session before rehearsal began, a detail that circulated widely and set an early tone for how the production is approaching its historical material.

The Seoul Museum of History is currently hosting a tie-in exhibition titled 1932 Gyeongseong: Becoming a Spy, where visitors can move through a mission scenario modeled on the drama's premise. Actual props and furniture from the set are on display through the 27th, and an audio guide narrated by cast members runs through November 29.

100 Days of Lies is a 16-episode series. It premieres October 10 at 9:10 p.m. KST on tvN.