So Ji-sub discusses 'Mercy for None,' iconic webtoon turned into series

Veteran K-drama star responds to 'Mercy for None' backlash, reflects on his passion for noir genre

So Ji-sub (Netflix)

Adapting a hit webtoon into live action has become a go-to move for drama creators, lowering risk while guaranteeing a ready-made fanbase eager to leap from digital panels to episodic storytelling. It is no surprise that original screenplays are becoming the exception rather than the rule in today’s drama landscape.

Netflix Korea’s tentpole series “Mercy for None” rode that wave, bringing one of the most critically acclaimed webtoons to life with a star-studded ensemble cast. Fans were especially thrilled by the casting of So Ji-sub as the lead — a longtime fan-favorite pick to embody the webtoon’s ruthless protagonist.

However, adapting beloved material comes with risks: Since its June 6 premiere, “Mercy for None” has faced backlash from loyal webtoon fans over major plot changes.

So, a veteran actor known for past hits such as "I’m Sorry, I Love You" (2004) and "Master’s Sun" (2013), acknowledged the mixed reactions during a group interview held Thursday in Seoul’s Samcheong-dong.

“When adapting a webtoon into a series, it’s not like the intention is to harm it or make it worse,” said So.

“In some ways, there’s an effort to create an even better piece, something that surpasses the original. Of course, once it’s completed, there will inevitably be mixed opinions," he added. “That’s not something that can be controlled. But at the very least, I don’t think the original (webtoon) is ever purchased with the intent to damage it.”

"Mercy for None," starring So Ji-sub (left) and Huh Joon-ho (Netflix)

In embodying his character, So reflected on the emotional depth he aimed to bring to Gi-jun, a cold-blooded former gangster on a path of vengeance following his brother’s murder.

"I naturally tried to capture the vibe that character gives off. Of course, I couldn’t imitate every look or gesture, but I tried to hold that essence in my heart. I’m not sure if I fully succeeded, but that was my mindset." He added, "I hoped that Gi-jun’s revenge for his brother, along with his desperate and pitiable sides, would come through."

“Mercy for None” marks So’s long-awaited return to the action genre, 13 years after his turn as a corporate assassin in "A Company Man."

With Korean audiences long accustomed to iconic action figures, from genre staples such as "John Wick" and local heroes like Detective Ma Seok-do from the hit "The Outlaws" franchise, he reflected on how he approached the physicality of his role in "Mercy for None."

“There’s more action in this series compared to others,” So said. “To show Gi-jun’s almost invincible nature, I thought it was essential to convey power and energy. If you look closely at my action style, I might get pushed back, but I never dodge by stepping away. I really tried to incorporate that.”

He also pointed to the stripped-down dialogue as a key aspect of the performance. “There’s very little dialogue. I think we filled in those gaps with the help of the camera and the director’s guidance. Personally, I actually prefer roles without much dialogue.”

"Mercy for None," starring So Ji-sub (Netflix)

So’s return to the noir-action space with "Mercy for None" marks a homecoming to a genre he holds close. “I personally really enjoy the noir genre. It’s something I want to keep doing, even as I get older. Above all, I heard that the script for 'Mercy for None' came to me first, and I was especially grateful for that,” he said.

“When I reflect on myself, I think it’s a genre I’m good at. My acting style doesn’t involve dramatic emotional swings or a lot of expressive outbursts. I prefer roles that rely on physicality, subtle expressions or acting through the eyes. That’s why I think noir suits me well.”