The military coup in Seoul occurred on December 12, 1979, following the assassination of President Park Chung-hee. Major General Chun Doo-hwan orchestrated the coup, taking control of the government. The events of December 12, 1979, and the subsequent political developments had brought a massive impact on South Korea's history, leading to a period of military rule and significant societal and political changes.
The film, 12.12: The Day, dryly depicts events that took place just before and during the coup and the people involved in it. Veteran actor Hwang Jung-min played Chun Doo-kwang, a Major General who led the coup. Hwang was rivaled in the film by actor Jung Woo-sung, who played Lee Tae-sin, the commander of the Capital Defense Command (formerly known as the Capital Garrison Command).
Other famous actors such as Lee Sung-min, Park Hae-jun, Kim Sung-kyun, and Jung Hae-in played the main roles in the film. The names of characters in the film were differentiated from their real-life role models. For example, Chun Doo-hwan's name was changed to Chun Doo-kwang, and Jang Tae-wan was changed to Lee Tae-sin.
According to data released by the Korean Film Council (KOFIC), 12.12: The Day garnered more than two million viewers as of November 27, making it one of the fastest films to break the two million mark in South Korea's film history. More than 2.3 million people watched the movie as of November 28.