Question: What stage play was the film Lee Joon-gi starred as a clown in based on?

Context articles: My Jun, My Style
Lee Joon-gi
Iljimae
King and the Clown
Criminal Minds (South Korean TV series)
Arang and the Magistrate
Never Said Goodbye (film)
Scholar Who Walks the Night
Namoo Actors
Virgin Snow (film)

My Jun, My Style is the first single album by Lee Joon-gi.
 He released his mini album "My Jun, My Style" on April 26, 2007 which contains three ballads, which he wrote primarily for his fans at the Episode 1 fan meeting on May 21, 2006.
 In addition, this release comes with a DVD containing special footage of Lee's visits around Asia and behind-the-scenes footage.
 The photo album offers a first look at Lee's highly anticipated upcoming film Virgin Snow, which co-stars Japanese actress Aoi Miyazaki.
Lee Joon-gi (born 17 April 1982) is a South Korean actor, singer and model.
 He rose to fame on his first leading role playing a clown in the film "The King and the Clown" (2005) and the television series "My Girl" (2005).
 Since then, he has starred in television series "Iljimae" (2008), "Arang and the Magistrate" (2012) "Scholar Who Walks The Night" (2015) and "" (2016).
Iljimae (; literally "One blossom branch") is a 2008 South Korean period-action television series, starring Lee Joon-gi in the title role of Iljimae.
 It is loosely based on the comic strip "Iljimae", published between 1975 and 1977, written by Ko Woo-young based on Chinese folklore from the Ming dynasty about a masked Robin Hood-esque character during the Joseon era.
King and the Clown (, lit.
 "The King's Man") is a 2005 South Korean historical drama film, starring Kam Woo-sung, Jung Jin-young and Lee Joon-gi.
 It was adapted from the 2000 stage play, "Yi" ("You") about Yeonsangun of Joseon, a Joseon dynasty king and a court clown who mocks him.
 It was released on 29 December 2005, runs for 119 minutes; and distributed domestically by Cinema Service and internationally by CJ Entertainment.
Criminal Minds () is a South Korean television series starring Lee Joon-gi, Son Hyun-joo, Moon Chae-won, Yoo Sun, Lee Sun-bin with Go Yoon and Kim Yeong-cheol.
 The drama is based on the American television series "Criminal Minds".
 It airs every Wednesday and Thursday starting July 26, 2017 on cable channel tvN.
Arang and the Magistrate (; also known as Tale of Arang) is a 2012 South Korean historical television drama, starring Lee Joon-gi, Shin Min-ah and Yeon Woo-jin.
 The period horror-romance is based on the folklore of Arang, who died unjustly and returns as a ghost in order to reveal the circumstances surrounding her death.
 It aired on MBC from August 15 to October 18, 2012 on Wednesdays and Thursdays at 21:55 for 20 episodes.
Never Said Goodbye is a 2016 romance film directed by Lin Yu-Hsien and starring Lee Joon-gi, Zhou Dongyu and Ethan Juan.
 The film is Korean-Chinese production.
 It was released in China on August 9, 2016.
Scholar Who Walks the Night () is a 2015 South Korean television series based on the manhwa of the same name written by Jo Joo-hee and illustrated by Han Seung-hee.
 Starring Lee Joon-gi, Shim Chang-min, Lee Soo-hyuk, Lee Yu-bi and Kim So-eun, it aired on MBC from July 8 to September 10, 2015 on Wednesdays and Thursdays at 21:55 for 20 episodes.
Namoo Actors Co. Ltd. (Hangul: 나무엑터스 ; RR: "Namu Egteoseu " ), founded in 2004, is a talent management agency based in Seoul, South Korea.
 Its current roster includes Ji Sung, Moon Chae-won, Kim Hye-seong, Lee Joon-gi, Kim So Yeon, Yoo Ji Tae, Jeon Hye-bin, Kim Hyo-jin, Moon Geun-young, and Shin Se-kyung.
Virgin Snow (첫눈 - "Cheotnun", 初雪の恋 ヴァージン・スノー - "Hatsuyuki no koi") is a 2007 South Korean film directed by Han Sang-hye and starring Korean actor, Lee Joon-gi and Japanese actress, Aoi Miyazaki.