Jason Yu, who makes his feature film debut with mystery thriller “Sleep” on Sept. 6, already had garnered worldwide attention even before the movie’s opening here, with his film invited to the 76th Cannes Film Festival in May.

“Sleep,” starring Lee Sun-kyun and Jung Yu-mi as newlyweds, is set in motion by Hyun-soo's (Lee) strange behavior while sleeping. His pregnant wife Soo-jin (Jung) tries to stop him some way or another, in the film that screened in the noncompetitive Cannes Critics' Week.

“Cannes was an experience of 100 percent joy, although I couldn’t really enjoy it at the moment due to the overwhelming stress and anxiety I felt about unveiling my film for the very first time,” the 35-year-old director said in an interview with The Korea Herald in Seoul on Wednesday.

“Our film entails very Korean or traditional elements, but I think anyone can find it relatable to the plot and development of complications, because sleep is part of everyone and anyone’s life,” Yu said.

Though sleepwalking itself is not unfamiliar when it comes to horror or thriller flicks, Yu approaches the topic from a different perspective.

“At first, news articles on how sleepwalkers commit dangerous activities like driving a car or harming others sparked my curiosity on this topic. Then I wanted to delve into the everyday aspect of those suffering from sleepwalking, and then further tell the story from those around this person, such as family members, and what they will do to protect, confront and overcome the fear,” he added.

As the film takes place inside Hyun-soo and Soo-jin’s home throughout the 94-minute running time divided into three chapters, Yu said he had to maximize the set designs, such as by changing the interior or light props. The film’s limited budget was another reason for him to maximize the props to create the mood representing the couple’s mental state.

“Each chapter shows the stark mental changes of this couple, so I decided to drastically change the interior and look of the space. The first chapter draws home as a sweet, warm place, whereas the second chapter exudes the mood that a home could create claustrophobia,” Yu said, stopping himself from divulging the mood of the third chapter not to say too much about the ending.

Yu said his debut film was a great stepping-stone to learn more about cinema.

With no background in film school nor professional studies in film directing, he went straight to the field after graduating from university. He spent several years working with renowned directors like Lee Chang-dong for “Burning” in creating English subtitles and Bong Joon-ho for “Okja” as a coordinator on the sound mixing team. He also created two shorts films: “Video Message” in 2014 and “The Favor” in 2018.

“It may sound inappropriate, but I think ‘Sleep’ was a project for me to learn more about how to make a film. I borrowed a lot of professionalism from our art directors, sound directors, camera directors and other experts in this project. Because I lack such professional film techniques, I see myself as a director who is a storyteller, focusing more on finding good actors with good acting and a seamless storyline which can be easily noticeable by the audience,” Yu said.

“Also, my English subtitle translation experience shaped me to become a meticulous director who even checks English subtitles line by line,” Yu said, laughing.

As for the precious experience of having worked with Korea’s only Oscar-winning director, Yu said it is half pressure and half gratitude to see people pay attention to him as a rookie director coming from Bong’s mentorship.

“Bong worked as a positive stimulus for me. I poured my heart, soul, sweat and blood into this film because I had to do so. I really wanted to hear people saying, ‘Wow, he learned well from Bong,’” Yu said, adding that Bong had seen the edited version of “Sleep” and offered him many compliments and words of encouragement.

One thing Yu is particularly proud of in “Sleep” as someone who has learned under Bong -- who is known as a master of detail -- is the sound.

“I did put a lot of effort into the sound. I worked as a coordinator between director Bong and the sound mixing team during ‘Okja,’ and saw that at least 100 pages of documents were completed just by talking about fine-tuning the sound. I was really surprised. So I also worked very hard on the sound, creating a similar length and thickness of the booklet on ‘Sleep,’” he said, adding he is “super confident about the sound.”

“Sleep” hits local theaters Sept. 6.

The following article is the eighth in a series that introduces Korea’s new and emerging actors and directors. -- Ed.