Actors Jo Jung-suk, left, and Yoo Jae-myung pose during a press conference for the upcoming film, "Land of Happiness," at a theater in Seoul, Monday. Yonhap

As the late "Parasite" actor Lee Sun-kyun's final work "Land of Happiness" is set to hit theaters soon, the co-stars of the period film were overwhelmed with emotions and struggled to hold back tears as they recalled their ensemble with the late actor.

"Land of Happiness" delves into the historical context of the 1979 assassination of former President Park Chung-hee, centering on the story of Park Tae-joo (Lee) who becomes involved in the assassination under his superior's command and the lawyer Jung In-hoo (Jo Jung-suk) who defends him.

Director Choo Chang-min, best known for the 2012 film "Masquerade," said that through this film, viewers will be able to "see what a great actor Lee Sun-kyun was."

"If there's one thing I can guarantee, it's this: when viewers watch this film, they will realize what an excellent actor we've lost," Choo said.

Choo also mentioned that the late actor told him that he had decided to participate in the film because actor Jo was in it.

"Lee Sun-kyun told me that he thought Jo Jung-suk was a really good actor and that he wanted to work with Jo and learn from him," the director said. "I was surprised by his attitude. I thought such a good actor still had curiosity and aspirations and approached acting with a learning mindset."

In response, Jo, with tears in his eyes, said it was an honor to appear in the same work with Lee.

"Lee also told me like that and I thought he was joking. I'm really grateful. I relied on him a lot too," he said. "In this work, viewers will be able to see a weightiness and seriousness in Lee Sun-kyun that they haven't seen before."

Actors Jo Jung-suk, front, and Lee Sun-kyun, behind microphone, are seen in a poster for the upcoming film, "Land of Happiness." Courtesy of NEW

The actor said he took interest in the project because it is based on the much-discussed historical event but tells the stories of lesser-known figures.

"I knew about the presidential assassination in 1979, but when I first read the script, I was very interested in the story of a person I didn't know, a new character. Personally, it was also a historical study and while playing attorney Jung In-hoo, I had a strong desire to defend him. That's why I wanted to be part of this story," Jo said.

Actor Yoo Jae-myung played Chun Sang-doo, a character motivated by former President Chun Doo-hwan. In actual history, Chun, as chief of the Army Security Command, led the investigation into former President Park's death when he was assassinated on Oct. 26, 1979.

"As it's based on a real person, I tried to portray the character of the former general within the context of the work without deviating from it," Yoo said.

Remembering the late actor, Yoo said, "When I think of Sun-kyun, only good memories come to mind. He was a wonderful friend and colleague. I still miss him."

"Land of Happiness" will hit local theaters on Aug. 14.