Netflix Hit Teach You a Lesson Star Kim Moo-yul Praised for Heartwarming Off-Screen Behavior

Actor Kim Moo-yul, currently generating massive buzz for his hard-hitting role in the Netflix series Teach You a Lesson, is earning widespread praise for a completely different reason. A touching behind-the-scenes story from the set is winning over viewers who previously only knew him as the show's sharp-edged protagonist.

On JUNE 17, the mother of child actor Choi Ja-woon—who appeared as Woo-jin in the fifth episode of the series—took to social media to share a moving experience regarding Kim.

"He is so completely different from the charismatic teacher Na Hwa-jin on screen," she wrote, posting several heartwarming photos. "He is incredibly warm and kind, and Ja-woon absolutely adored him." The shared images captured Kim celebrating his birthday alongside the child actors on the set of Teach You a Lesson.

"During filming last May, it happened to be Kim Moo-yul's birthday," Choi's mother recalled. "During a break between takes, Ja-woon, his friends, and the younger children gathered to sing him a birthday song. He smiled so brightly and greeted every single one of them. It was a beautiful moment that made the children so incredibly happy."

She further highlighted Kim’s attentive care on set, writing, "When Ja-woon asked to take a selfie in the waiting room, Kim gladly posed with him. Each time, he naturally bent down to match Ja-woon's height. It was a brief shoot, but the warmth and genuine care he demonstrated on set will stay with us for a very long time."

Teach You a Lesson follows a specialized teachers' rights protection bureau that intervenes on behalf of victims and works to eradicate systemic violence within classrooms. Following its release, the high-stakes procedural drama captured the No. 1 spot on Netflix’s daily Top 10 chart in South Korea. It has since gone on to hit No. 1 on Netflix’s Global Top 10 for non-English shows and dominated FlixPatrol’s global Netflix TV show rankings. Kim anchors the series as Na Hwa-jin, a brilliant yet merciless inspector within the bureau.