Royal Secret Agent

Royal Secret Agent is a South Korean historical comedy, detective television series. The series is directed by Kim Jung-min and stars Kim Myung-soo, Kwon Nara, Lee Tae-hwan, Lee Yi-kyung, and Jo Soo-min. Written by Kang Min-sun and Park Sung-hoon the series is about a government position in Joseon dynasty known as Secret royal inspector, who monitors corrupt government officials while remaining undercover. It aired on KBS2 every Monday and Tuesday at 21:30 (KST) from December 21, 2020, to February 9, 2021.

Synopsis
Set in the era of Joseon dynasty the series revolves around Sung Yi-gyum (Kim Myung-soo), a state examination top scorer who works in the administrative and research department of the government office. He is caught gambling and as punishment, he is reassigned to a new position as a secret royal inspector to investigate the corrupt practices of public officers. Yi-gyum carries out his new job with the help of Hong Da-in (Kwon Nara), a female inspector, and Park Chun-sam (Lee Yi-kyung), his talkative but affectionate servant.

The three musketeers

 * Kim Myung-soo as Sung Yi-gyum, a secret royal inspector
 * Kwon Na-ra as Hong Da-in/Honglang/Lee Young-sin, female police posing as a courtesan whose beauty is comparable to Hwang Jini. She becomes a member of Royal Secret Agent's entourage.
 * Lee Yi-kyung as Park Chun-sam, Sung Yi-gyum's servant.

Around three musketeers

 * Lee Tae-hwan as Sung Yi-beom, Sung Yi-gyum's half-brother, head of the band of vigilante
 * Jo Soo-min as Kang Soon-ae, Sung Yi-gyum's ex-lover, daughter of a courtesan

Supporting

 * Ahn Nae-sang as Jang Tae-seung, Chief Royal Secretary
 * Son Byong-ho as Kim Byeong-geun, Chief State Councillor
 * Kim Young-cheol
 * Choi Jong-won as Kang In-chung, corrupt sheriff
 * Ha Young as Kim Mi-ok
 * Park Joo-hyung as Seo Yong
 * Kim Kyung-sook
 * Lee Min-woo
 * Um Hyo-sup
 * Chae Dong-hyun as Kim Man-hee, Kim Byeong-geun's first son
 * Jong Ho as Man Deok
 * Shin Ji-hoon as Choi Do-kwan
 * Jo Deok-hee as Jung Moon-ho
 * Yang Byung-yeol as Civil servant Kim

Production
By July 2020, the main cast of the series with Lee Tae-hwan, Kim Myung-soo, Kwon Nara and Lee Yi-kyung was finalized. The broadcast was initially scheduled to be premiered on November 2, 2020, but due to re-proliferation of COVID-19, the production was delayed. In October, group script reading was held. The still photos in the period costume, from the set of series were released by KBS as the filming progressed.

Viewership
As per the audience rating of AGB Nielsen Media Research, the second part of the final episode, recorded 14% average TV viewership ratings. This is the highest record for its ratings.

International broadcast
The series is available same time as Korea, as an iQIYI Original and exclusively on iQIYI globally (except China and Korea) with multi-languages subtitles. It is also available non-exclusively on iQIYI in South Korea.