6 interesting facts about the Netflix K-drama Hellbound

One of the defining aspects that draws people to K-dramas is the realistic depiction of human nature and societal issues. Be it director Jung Dong Yoon of Gyeongseong Creature who revisits historical atrocities to highlight ongoing injustices, or director Yeon of Hellbound, who tried to mirror the societal wrongs in their shows, it's this mix of realism and art that gives K-dramas their unique color. So, although Hellbound leaves viewers with many questions about its supernatural elements, the focus of the series is actually in its portrayal of the extreme sides of human nature  — how opportunists can exploit fear and twist religion for personal agendas. 

Director Yeon, in an interview, emphasized that "rather than trying to explain the mysterious events, I thought it was more important to convincingly depict the people involved in those situations." 

Moreover, in an interview with Forbes, when director Yeon was asked if the idea behind New Truth and the Arrowhead came from religious cults in Korea, he said, "The New Truth Society can be seen as an embodiment of powerful forces that create and push their own propaganda. They don’t necessarily have to be related to religion though. And the series depicts people who follow them.

In Korea, a lot of this stuff actually happens on the internet. So the idea for the New Truth Society didn't originate from any religious group per se, but rather from people who create and promote their own propaganda in general, and people who shape public opinion online. We crafted Season 2 with the thought that it was going to be a story about people who try to advance their own ideologies — whether it’s the Arrowhead, [Senior Secretary] Lee Su Gyeong, those who attempt to take advantage of Park Jung Ja — basically, people who try to create ideologies that are favorable to their goals."

And there's more where that came from. From high-octane action sequences and physical transformations to powerful performances, Hellbound demanded immense dedication and effort from the cast and crew.  

Searching for more insights about how Hellbound came to our screens, we compiled some of the interesting facts about the Netflix series. Ready for a deep dive? Here are some behind-the-scenes stories about Hellbound that might just change the way you experience this Netflix phenomenon. 

1. Kim Hyun Joo shares her experience performing action scenes for Hellbound

In the K-drama, Kim Hyun Joo takes on the role of Min Hye Jin, the leader of Sodo. Min Hye Jin is a character with a strong belief in justice, living in a chaotic world where proclamations and demonstrations occur constantly. She leads the organization Sodo in its fight against the New Truth Society, which incites the people, and Arrowhead, which engages in indiscriminate acts of terrorism.

During an interview with local reporters, Kim Hyun Joo talked about her experience doing action scenes in the K-drama. She said, "Since I had never done a genre work or action before, starting with Hellbound Season 1 was challenging and heavy." However, she added, "But as I continued, I improved." She went on, "There were some movements that I've done before, of course, but if the action were just about playing a character who’s good at fighting, there would have been plenty of others who could do it better. The challenge was that through the action, I had to convey Min Hye Jin's emotions, hardships, and beliefs built up over four years. That wasn't easy." 

Regarding her approach to the action scenes in Season 2, she explained, "I wanted it [the action scenes] to look strong. Since she's fighting men and performing high-level action, of course, agility is important, but I also wanted to have a sense of weight." She continued, “A lot of it was physically demanding, and I realized I needed stamina to complete them. So, I worked on building my stamina, which led to some weight gain as well."

Kim also said, "I never got injured," and added, "They absolutely wouldn't let me do anything too risky." She continued, "The car chase scene looks scary and dangerous, but filming it wasn't like that at all. These days, things have really advanced," she remarked with admiration. She also shared, "I had to drive a large vehicle, but I only had a Class 2 driver's license, so I first got a new license. I actually enjoy driving and have a good sense for it."

Regarding how confident she was with the action scenes in Season 2, given the success of Season 1, Kim Hyun Joo commented, "I did have more confidence than in Season 1, but action scenes are always unpredictable, as you never know what kind of accident might happen, so I stayed alert." She added, “And my body has also changed; it's already been three years since Season 1. So, if the timing was even a little off and the synergy wasn't right, I could have ended up actually getting hit, so I had to stay extremely focused and alert throughout filming."

Kim Hyun Joo also shared, "The director said, ‘If possible, I'd like you to do the last action scene yourself. I want it to be a realistic and fierce fight.' Half-jokingly, he mentioned the action scenes of Keanu Reeves in John Wick. I watched John Wick 4 at home, and I understood what he meant. It's that heavy, desperate feeling, like you're clinging on with all you have. The action really reflected Min Hye Jin's character, who was exhausted but kept throwing punches until the very end." 

Kim continued, "I thought Min Hye Jin would have to toughen up to uphold her beliefs... She's fearless, ruthless, and unhesitating. I wanted to show her boldness, and without that, I felt there'd be no way to fully express Min Hye Jin."

The result was the product of months of grueling training. She said, "The training process was tough but it was so good. I love sweating it out together, syncing movements, helping, and caring for each other. I actually enjoyed the training more than the filming itself."

Recently, influenced by the Hellbound series, she started kickboxing as a hobby. "I've always liked action. I feel an itch to move around, like I want to let it all out. It's different from weight training; kickboxing is a perfect fit for me," she added with a laugh, "I think I picked it up quickly because I enjoy watching UFC."

Kim Hyun Joo added that she would be willing to take on another action project, saying, "Using my body relieves stress, and going to action school regularly, I also break a sweat. Preparing for action takes months, which makes it even more fulfilling. What shows on camera is a reflection of my own efforts, so it is a really enjoyable experience." 

2. Kim Sung Cheol dieted for 5 months and lost 8-10kg for Hellbound Season 2

Director Yeon Sang Ho, along with Kim Hyun Joo, Kim Sung Cheol, and Im Sung Jae appeared as guests on the Korean variety show MMTG Civilization Express, where they shared interesting anecdotes about the behind-the-scenes of Hellbound Season 2.

Kim Sung Cheol shared an interesting fact about how he prepared his body for the scene of Jung Jin Soo's resurrection.

Pointing to the scene, he said, "That was filmed for the third or fourth time. I was shirtless...  I ate eggs that day and thought, 'I'll hang in there until tomorrow.' By the third day, though, I just couldn't hang on anymore. How could anyone hang on?"

Director Yeon said, "Knowing he was dieting and going through all that, we originally scheduled the shoot earlier. But, because of an incident involving Im Sung Jae, one scene was significantly delayed. Originally, he only had to keep the diet strict for a short period."

Kim continued, "But I ended up doing it for five months. After hearing the shoot might be delayed a bit because hyung (Im Sung Jae) got injured, I thought, 'Okay, I can eat,' and I ate for about two days. I got really swollen. You'll notice [when the scene comes out ] later — I was really swollen."

Director Yeon joked, "There's a lot of dust in that scene. We use things like soybean powder to make it. In the summer, when soybean powder is sprinkled around, in that state [when you're dieting], you might even end up eating it."

In an interview with local reporters on October 30, Kim Sung Cheol said, "Since I normally work out a lot, I ended up 'cutting down' quite a bit. I reduced muscle mass and dieted hard to appear lean. I also managed my water intake. Compared to now, I lost about 8-10 kg over five months. I kept up with the diet during filming and barely ate on set. But, honestly, while playing Jung Jin Soo, I didn't even have an appetite. It wasn't too difficult since I didn't feel like eating."

Kim added, "I combined a strict diet with cardio exercises and minimized strength training. Every morning, I'd go up the mountain behind my house to sweat it out, and if I had a schedule, I'd work out after it was done. My diet consisted only of eggs and bananas." 

The actor also said, "To convey the imposing aura Jung Jin Soo has, I paid close attention to my gaze. It's a look that says, 'I am superior to you.' Even if it's a lie, he has to project that in front of others."

3. Yoo Ah In delivered lines spanning two pages in a single take in Hellbound Season 1 

In Hellbound Season 1 Yoo Ah In and Yang Ik June flawlessly executed a scene with long lines that had been changed just a few hours before filming. 

Chairman Jung Jin Soo (played by Yoo Ah In in Season 1; the actor was dropped from Season 2 due to his drug scandal) of The New Truth preaches that the sudden supernatural events are God's warning to sinful humans, manipulating people. 

For the ending scene of episode 3 director Yeon Sang Ho deliberated until the last minute and revised the dialogue in the morning on the day of the shooting. Yoo Ah In then delivered his lines, spanning two pages, in a single take. His portrayal of Jung Jin Soo's anguish and loneliness, expressed almost like a scream, even led to changes in the storyboard.

"I felt the momentum from the first take, and I thought I shouldn't break it midway," said director Yeon, who immediately switched to filming the scene in one long take. The entire crew worked together seamlessly to capture the iconic moment. Yang Ik June, who was like a lighting technician shining a flashlight to amplify Jung Jin Soo's anxiety, also gave a perfect performance in reaction, maintaining the emotional intensity despite the sudden switch to a one-take format. 

The passionate performance from both actors, fully immersed in their characters and the situation, created a scene that leaves viewers around the world with a powerful question about human will and autonomy.

4. Director Yeon on the shift in the lead actor from Yoo Ah In to Kim Sung Cheol, and Kim Sung Cheol on the pressure he felt 

When asked if the change in the lead actor led to any challenges in production, director Yeon explained, "It was quite challenging. The Season 1 actor gave such an impressive performance, and although Jung Jin Soo is originally from the comic, most people remember Jung Jin Soo as the character from the series," adding, "And the actor who played Jung Jin Soo in Season 1 brought a lot of his own identity into the role. I couldn't ask Kim Sung Cheol to imitate Yoo Ah In; it wouldn't even be possible."

When asked, "Did you give any specific directions to Kim Sung Cheol on how to act?" he responded, "Since there is an original work, the actor said he would start from that. My concern was 'How can we naturally convey this to the audience?' Although many people know that the actor has changed, when framing the shots, rather than just putting Kim Sung Cheol's face right there in front, we chose to start with his silhouette, gradually moving into close-ups, or take a more gradual approach."

He continued, "To be honest, my biggest concern was that having an actor with high potential like Kim Sung Cheol play Jung Jin Soo might not necessarily be the best choice. I actually voiced this concern, and I kept expressing it to Kim Sung Cheol as well. We talked a lot about this. This is about the actor's success," adding, "However, Kim was more focused on how to portray the character of Jung Jin Soo from the original work rather than aiming for success in a conventional sense. He also has experience with double casting from his work in musicals, so he didn't feel as much fear as I did about those aspects."

He also added, "Kim Sung Cheol has a confidence actors of his age possess. He seemed to express things without hesitation. It must have taken considerable effort and analysis to reach that level. In truth, he must have felt immense pressure, as another actor had come to be seen as the original. That's quite a burden. Yet, with firm confidence and conviction, he pulled it off brilliantly."

When Kim Sung Cheol was asked if he felt any pressure filling Yoo Ah In's absence as Jung Jin Soo. He replied, "I wouldn't be human if I didn't feel any pressure. Even now, I worry about how people will perceive it. But being an actor is a profession where you're always standing in judgment, facing constant evaluation. Especially this time, it felt like an execution ceremony with so many people watching."

Still, Kim continued, "It's something that was inevitable, and it was the result of my own choice. I believed it was a responsibility I had to bear, so I approached it boldly. I've often been compared to others through double-casting in musicals, so I'm used to it, though it's not something I think is okay."

He added, "I really enjoyed the first season, Hellbound, and found the character Jung Jin Soo incredibly compelling. I also wanted to work with director Yeon Sang Ho at least once. So even though it was a major challenge, I thought, 'Let's dive into the fire,' and that’s how I joined.”

Kim also spoke about Yoo Ah In's performance in Hellbound, saying, "I think everyone felt the same way — it was like, 'Is he insane?' It went beyond just being good. It was truly shocking." He admitted, "I genuinely loved Yoo Ah In's portrayal. I thought, 'There's an actor who acts like that in Korea, and I want to try acting like that too.'"

However, he explained, "But mimicking Yoo Ah In is not my style, so while there were things I wanted to try, I reinterpreted Jung Jin Soo in my own way."

He also revealed, "The initial script I received had Yoo Ah In's lines from Season 1 [from the scene when Jung Jin Soo reveals to Jin Kyung Hoon (Yang Ik June) that he received a decree 20 years ago] written exactly as they were, so it was difficult. No matter how much I practiced, I couldn't find a way to make it feel new." "I kept seeing Ah In Hyung [in them]." "So I read the original again. I tried to take as much of the webtoon as possible. I reviewed the script every day from the first meeting with the production team until filming began to make sure I didn't miss anything. Through this process, there were also parts of the script that changed. Some lines [that were continued from] Season 1 were omitted, and the focus shifted. For Season 2, I aimed to use the webtoon's lines as they were and studied everything, even the parts that were edited out."

The actor added, "I'm grateful even to be compared. I think (Yoo) Ah In hyung has worked for a long time, done many projects, and is a talented actor. Even if it weren't me, I believe that someone like Timothée Chalamet from Hollywood would also be compared [if he played Jung Jin Soo]." 

5. Director Yeon opens up about the challenges he faced filming Hellbound Season 1

In an interview after the premiere of Season 1, when director Yeon was asked what was the most challenging scene to shoot, he replied, "The scene from episode 4, where Bae Young Jae (Park Jeong Min) watches his colleague's demonstration at a reservoir, was the most challenging to shoot. We filmed it in the middle of winter, so both the actors and crew had a hard time in the water. The action sequence of Min Hye Jin (Kim Hyun Joo) escaping her residence had to be shot in a single long take. We filmed that scene overnight for two days. Although it was tough, we were very proud of the end result."

In a Netflix commentary, talking about that same one-take action scene, director Yeon shared, "[Kim Hyun Joo] practiced so much at the action school."

But, Kim revealed that she "didn't do the whole thing. There was a stand-in. But it looked like I did everything."

Director Yeon further elaborated, "We had a lot of NGs [No Good]. The cameraman had to jump together [with the actress]. I think we did it more than 10 times."

Another memorable scene from Hellbound Season 1, is the opening scene that takes place in a cafe. Referring to the scene, director Yeon said, "This is a set. We blew it all up because it had to be. That's why we made a set. We put a lot of effort into the opening scene."

Park Jeong Min revealed that an entire street in Sangam-dong was blocked off for filming.

"Yes. We filmed it in Sangam-dong. About two blocks? [I think]. I didn't know that was possible in Korea." "The car crashing scene was done at an open set. We divided it into three sections," he added, explaining that the inside of the café interior was shot on a set, while the shots outside the cafe were filmed on location.

6. The journey of Hellbound: From animation to Netflix K-drama 

In a Netflix commentary, director Yeon shared how it all began for Hellbound.  

He stated, "I made an animation under the same title when I was in college [at the age of 20]. I made it alone. I came up with multiple settings as time passed but Hellbound was just perfect. Hellbound seems like the perfect fit. [I was like] 'Let's make it again!' [I wondered,] 'What would it look like if I make it completely new after 20 years?'"

In 2019, the webtoon for Hellbound came out, which Yeon created with illustrator Choi Gyu Seok. That webtoon was adapted into a Netflix series and released on November 19, 2021. 

On December 6, 2021, Naver Webtoon reported that following the release of the Hellbound Netflix series, the original webtoon saw its average weekly views surge by approximately 22 times, with weekly paid views rising around 14 times. 

When Hellbound Season 2 was confirmed for production, director Yeon announced he would also release the second part of the webtoon and that the webtoon would be released first, followed by the drama. However, while the K-drama's filming schedule was already announced, there had been no news about the webtoon — until, at last, on September 30, 2023, the serialization of "Hellbound 2: Resurrection" began. 

Webtoon fans can catch "Hellbound" and "Hellbound 2: Resurrection" on Naver Webtoon.

Bonus: Director Yeon on plans to expand the Hellbound universe 

In an interview, when asked about the possibility of Season 3, director Yeon suggested a new approach rather than focusing on a third season. He explained, "There are plans to expand the Hellbound universe even further. Currently, we are working on an anthology that's a compilation of short stories by other creators. This collection of Hellbound short stories will be released soon, and is tied to the expansion of this series. Whether it moves to the screen is undecided. This isn't in the format of a Season 3 but rather an expansion like an anthology. It could be a different format — it could even be animation. It isn't necessarily limited to live-action film." 

He also said, "I hope this serves as a sort of catalyst. For me, Hellbound is like Gundam. Gundam has many sequels, but their worldviews are different. However, everything that emerges is embraced within the Gundam world. Hellbound is similar. We are preparing an anthology based on the Hellbound universe with the publisher, where different writers can let their imaginations run wild within its world. Stories from other countries would be interesting, too. Still, since I'm the 'Hellbound expert,' I can set the 'rules'. I can't do much with Train to Busan since it's not mine, but as I hold the copyright for Hellbound, I'm considering expanding its universe. It's a kind of 'fan fiction.' I created Parasyte: The Grey as a fan work of Hitoshi Iwaaki's manga 'Parasyte', which I love. When I'm out of ideas, I look at other works, like Haruki Murakami's short stories, and try to make them as fan fiction. That leads to some unexpected results, pushing the boundaries."