100 Days of Deception (Korean: 100일의 거짓말) is an ongoing South Korean television series written by Ryu Bo-ri and directed by Yoo In-shik and Kim Yoon-jin, as a special project commemorating the 20th anniversary of tvN. The series stars Kim You-jung, Park Jin-young, Kim Hyun-joo, Lee Moo-saeng, and Jin Seon-kyu. Set in 1932 Gyeongseong during the Japanese colonial period, it premiered on tvN on October 10, 2026, and airs every Saturday and Sunday at 21:10 (KST). It is also available for streaming on TVING in South Korea and Netflix globally.
Contents
Synopsis
Gyeongseong's most skilled pickpocket and con artist, Lee Ga-kyung, dreaming of earning enough to escape Joseon and start a new life abroad, agrees to go undercover as an interpreter at the Japanese Government-General of Korea for 100 days on behalf of the independence movement. There, she crosses paths with Kim Tae-woong, also known as Sato Hideo, an elite interpreter and the adopted son of Director-General Sato Shinichi. As the two become entangled in secrets and hidden loyalties within the colonial government, their lives intersect amid espionage, danger, and the growing struggle for Korean independence.
Cast
Main
Kim You-jung as Lee Ga-kyung / Geum Seo-hee
Gyeongseong's best pickpocket, she dreams of going to America. While saving money to achieve her goal, she accepts an offer from the anti-Japanese Korean independence movement Gu-guk-dan and becomes a spy, infiltrating the Government-General of Korea disguised as an interpreter for 100 days.
Park Jin-young as Kim Tae-woong / Sato Hideo
The adopted son of Sato Shinichi and a newly appointed elite interpreter for the Government-General of Korea. Fluent in English, Japanese, and Korean, he returns to Korea after more than 10 years abroad and takes on an important role as an interpreter.
Kim Hyun-joo as Yoo So-ran
A sniper for the anti-Japanese independence group Gugukdan who takes up arms in pursuit of revenge. Previously involved with Sato Shinichi, she returns to Korea after more than a decade under a new identity as a Chinese woman and marries Korean-American journalist Yoo Phillip for convenience. During an assassination attempt on Sato, she presents Lee Ga-kyung with a dangerous, life-threatening deal.
Lee Moo-saeng as Yoo Phillip
A Korean-American and correspondent for an American media company stationed in Gyeongseong. As a member of Gugukdan and a journalist, he uses his position and knowledge of international affairs to put pressure on the Political Chief of the Government-General, while maintaining a marriage of convenience with Yoo So-ran.
Jin Seon-kyu as Sato Shinichi
The newly appointed Inspector-General of Korea and adoptive father of Sato Hideo. An ambitious man willing to do anything for success and advancement, he becomes the primary target of Gugukdan.
Supporting
Seo Jeong-yeon as Ryu Gwan-sil / Yanagi
A Korean housekeeper who has worked for the Sato family for many years. She helps Tae-woong retain his Korean language and is one of the few people who remembers his mother.
Oiko Kiko as Sato Hanako
Sato Shinichi's daughter and Tae-woong's younger half-sister. She has used a wheelchair since birth and is particularly close to Tae-woong. After returning to Gyeongseong, she becomes curious about her Korean mother, who died giving birth to her.
Park Jung-yeon as Kim Myeong-nam
The only daughter of Kim Seung-eok, the president of Joil Textile, and a prominent pro-Japanese collaborator. She secretly loves Lee Yeong-bok and becomes involved with the Gugukdan after following him. She secretly sells jewelry given to her by her father to help fund the organization.
Lee Seon as Lee Yeong-bok
The secretary of Kim Seung-eok at Joil Textile and a member of the Gugukdan. Born into a family that had served the Kim family for generations, he became Seung-eok's secretary because of his intelligence. He secretly diverts company funds to support the independence movement and harbors feelings for Myeong-nam.
Kim In-kwon as Han Cheol-ryong
One of the senior members of the Gugukdan. After being arrested and imprisoned during an earlier operation, he went to the organization's headquarters in Shanghai and has recently returned to Gyeongseong. He remains unmarried, claiming that he will not marry until Korea gains independence.
Choi Deok-moon as Gwak Un-hak
A longtime member of the National Salvation Corps and an associate of Han Cheol-ryong. He works as a traditional Korean medicine healthcare provider at Hanseong Korean Medicine Clinic in Jongno, where most of his patients are poor Koreans who cannot afford treatment.
Production
Development
The series is developed by Studio Dragon and produced by Studio Dragon and Nangman Crew. Yoo In-shik directs the series from a screenplay written by Ryu Bo-ri, marking their first collaboration. Yoo previously directed Dr. Romantic (2016–2023) and Extraordinary Attorney Woo (2022), while Ryu wrote Do You Like Brahms? (2020) and Trolley (2022).
The first script reading took place on February 6, 2026.
Casting
In October 2024, Kim You-jung was reported to have been cast in the lead role. The following month, Kim Hyun-joo was reported have received an offer to join the series. In July 2025, Park Jin-young was reported to have been cast as the male lead, followed by Jin Seon-kyu in December. tvN officially confirmed the main cast, including Lee Moo-saeng, in February 2026.
Filming
Principal photography began in March 2026. Filming locations include Nonsan Sunshine Land in South Chungcheong Province, which was confirmed as a key filming location and main backdrop for the series and was previously used in the television series Mr. Sunshine.
Release
100 Days of Deception premiered on tvN on October 10, 2026, airing every Saturday and Sunday at 21:10 (KST). It is also available for streaming on TVING in South Korea and Netflix globally.
Marketing
On July 2, with 100 days left until the drama's premiere, a special teaser was released, continuously highlighting the keyword "100" to captivate viewers.
On August 11, 2026, tvN announced a special exhibition titled 100 Days of Deception Special Exhibition: 1932 Gyeongseong, Becoming a Spy at the Seoul Museum of History. The exhibition presents the setting and characters of the series. The first-floor lobby exhibition runs from August 14 to September 27, 2026, while a display in the museum's third-floor permanent exhibition area runs from August 14 to November 29.
On September 21, tvN launched an interactive promotional website for 100 Days of Deception, allowing users to explore content related to the series and its 1932 Gyeongseong setting.
On September 22, tvN announced a special broadcast titled 100 Days of Deception: Secret Documents, scheduled to air on October 3, 2026, at 22:30 (KST), one week before the series premiere. The broadcast features the main cast introducing the series and their characters, with television personalities Tak Jae-hoon and Kim Jong-min serving as hosts.
Viewership
According to Nielsen Korea, 100 Days of Deception premiered with a nationwide viewership rating of 5.3% and a metropolitan area viewership rating of 5.4% on October 10, 2026. It also recorded the highest premiere rating among tvN's Saturday–Sunday dramas aired in 2026.
