Meet Seo Sumin, the Rookie Actress Behind Agent Kim Reactivated's' Breakout Role

Seo Sumin never told her friends that she was training to become an actress. She realized just how well she had kept the secret the morning after her debut episode aired.

"I hadn't told the people around me that I was acting," she said. "So the day after the first episode of 'Agent Kim Reactivated' aired, I had a lot of missed calls. The reaction I remember most was, 'Wait, is that you, Min-ji?'"

It was the moment Seo made her arrival as an actress.

Seo made her debut in the SBS Friday-Saturday drama "Agent Kim Reactivated," an action series about an ordinary father, played by So Ji-sub, whose life is turned upside down when his daughter is kidnapped. Seo plays the daughter, Kim Min-ji. Despite having almost no on-camera experience, she made a strong impression from the opening episode.

Seo landed the role through an audition. She did not major in acting or receive formal training at school, beginning acting lessons only after signing with her agency. The audition tape that secured her the role was filmed early in that process.

"It was a video I recorded about three months after joining the agency," she said. "I performed a scene from 'Twinkling Watermelon,' but rather than copying the original scene exactly, I tried to express the emotions I felt while reading the lines. I hadn't been studying acting for long, so my eye lines and delivery felt awkward. I wasn't happy with it. But the director saw something in the video. I think what moved him was that it didn't feel like I was acting."

Before appearing in "Agent Kim Reactivated," Seo was already familiar to a corner of the internet. Short YouTube clips documenting her everyday life surpassed 3 million views, and she had accumulated more than 300,000 social media followers before making her screen debut. Some dubbed her "the actress discovered by the algorithm."

"The YouTube video that went viral was something I uploaded simply to preserve memories with my high school friends," she said. "I was already signed with an agency at the time, and I actually got in trouble for posting it. Then I uploaded another video three months later, and so many people enjoyed it. I was simply grateful."

Her online following also brought a label that she has been trying to move beyond. Some viewers initially dismissed her as an influencer attempting to become an actress, while her lack of acting experience only fueled the skepticism. From the first episode, however, Seo earned praise for her portrayal of Min-ji, shifting naturally between the subdued pain of a school-bullying survivor and the everyday emotions of a daughter at home.

"I've never thought of myself as an influencer," she said. "I want to continue showing good performances in different projects so that label doesn't follow me. The positive reviews made me happy, but more than anything, I felt relieved. This was So Ji-sub's return after a long break, and the original story already had a large fan base. I was genuinely worried that I might disappoint people."

"Agent Kim Reactivated" is So Ji-sub's first SBS drama in 13 years, following "The Master's Sun" in 2013. Seo said playing his on-screen daughter felt surreal.

"It felt as though there was a halo behind him," she said with a laugh. "I kept thinking, 'I'm supposed to be his daughter?'"

She still vividly remembers her first day on set.

"There were cameras everywhere, and it was very different from what I had imagined. I was extremely nervous. Then So Ji-sub handed me a strawberry candy and said, 'Let's do this, daughter.' I texted him recently as well. At the beginning of filming, I called him sunbae. Now I call him 'Dad.'"

Their chemistry translated onto the screen. "Agent Kim Reactivated" posted a rating of 23.1 percent, establishing itself as one of the year's biggest drama hits. Seo is now being mentioned as a strong contender for Best New Actress at this year's SBS Drama Awards, and she is candid about wanting to win.

"There are so many talented actors, so I would be happy just to be nominated," she said. She then smiled and added, "But my goal is to win the rookie award."

For now, however, Seo is looking beyond the trophy.

"Becoming famous would be nice, but I want to be an actress whom people remember for a long time," she said. "Watching films and dramas has broadened the way I see the world. I want to become someone who can do the same for other people."