KPop Demon Hunters‘ Lee Byung-hun, who voices the terrifying Demon King Gwi-Ma in Netflix’s runaway hit, has revealed why he joined the animated musical movie. KPop Demon Hunters took the world by storm when it premiered on Netflix earlier this year, even enjoying an exceedingly rare limited theatrical run following its debut on the streamer. A Demon Hunters sequel has since been confirmed, too.

While much of KPop Demon Hunters’ success is due to its catchy, K-pop-inspired soundtrack, Rumi’s (Arden Cho) struggle with her half-demon identity and Jinu’s (Ahn Hyo-seop) festering guilt and subsequent redemption resonated deeply with audiences. At the center of their journey toward self-acceptance is Gwi-Ma, whose hunger for souls and suffering exacerbates their deepest insecurities and tests their inner strength.

In an interview with ScreenRant‘s Ash Crossan for his new film No Other Choice, Lee Byung-hun shared his reaction to KPop Demon Hunters’ acclaimed storytelling and the heartwarming personal reason he decided to join the movie’s cast long before its soundtrack reached the top of the charts. “That was beyond expected!” The actor, known for his role as the elusive Front Man in fellow Korean Netflix hit Squid Game, explained.

“Of course, I first met the director and producer five years ago at Sony, and we had a meeting a few times, and I thought, ‘Yeah, why not? Why [not] just try?’” Byung-hun continued.

“I had a personal reason because I have a 10-year-old boy and a 2-year-old girl, and I couldn’t show them most of my movies. They’re great, but they’re very violent. So, I thought, ‘Yeah, let’s make an animation. Let’s participate in some good animation and show my kids.’ That was the main reason. And now, my daughter’s always listening to “Golden” and every other song in KPop Demon Hunters. They love it!”

When asked if his children recognized his voice during Gwi-Ma’s scenes, Byung-hun shared that his daughter “doesn’t know,” while his son was a “little bit disappointed.” “‘Why are you a demon? Why are you the villain?’ While he was watching the movie, he said, ‘I’m still on your side, not the Hunters’.’”

Of course, as Gwi-Ma’s greed and hunger threaten to destroy the protective shield of the Honmoon and tear Huntrix apart, it becomes harder and harder to support the Demon King. Byung-hun revealed that, by the end of the movie, his son said, “I cannot root for you anymore,” and that he was “kind of sad.”

While his son’s emotional response is understandable, it also proves the effectiveness of Byung-hun’s performance in KPop Demon Hunters and Gwi-Ma’s evil plans. A villain can make or break a fantasy story; for a villain that is essentially presented as an abstract, terrifying, insatiable, mouth-only entity, the character’s voice and dialogue become even more important.

Though Gwi-Ma and his demon lackeys were successfully banished by the end of KPop Demon Hunters, that doesn’t mean they won’t try to take over humanity once again. What’s a few more years for a Demon King, one who has waited eons to exact his revenge? Gwi-Ma, his manipulative prowess, and Lee Byung-hun’s corrupting voice performance may yet return in KPop Demon Hunters’ highly anticipated sequel.