Kim You-jung reinvents herself in Tving’s year-end bet 'Dear X'

Kim You-jung — long celebrated as the nation’s “little sister” since her early days as a child star — steps into her darkest role yet, shedding her bright image to play a cold-blooded sociopath in one of Tving’s biggest swings for the latter half of 2025.

In “Dear X,” Kim stars as Ah-jin, a top actor with a traumatic past marked by childhood abuse, who strategically cycles through lovers as stepping stones to fame. The 12-episode thriller traces her ascent as she weaponizes charm, beauty and calculated detachment, walking the uneasy space between victim and villain as she claws for survival.

Much of the show’s appeal comes from tracking Ah-jin’s icy, adrenaline-charged descent. Her immaculate styling and composed exterior conceal a trail of manipulation, revenge and violence, creating a protagonist who is difficult to love yet impossible to look away from. Her moral ambiguity, paired with flashes of buried pain, pushes viewers to both recoil and root for her, according to Tving.

For Kim, whose leading-lady credits lean heavily toward rom-com hits like “Love in the Moonlight” and “My Demon," “Dear X” represents a seismic shift.

“Because I’ve always had a bright, cheerful image, I hoped that when I took on a character with the complete opposite vibe, audiences would be able to accept that shift the moment they saw me,” she said during a press interview in Seoul on Tuesday.

Her objective was to keep viewers off-balance.

“From the beginning, I actually hoped that viewers would end up feeling deeply conflicted and even confused later on — in a good way. So while acting, I kept thinking that I needed to stay in that subtle space where the audience can neither fully hate nor fully root for the character. ... I’m glad that the things we were worried about ended up coming through naturally in the final work," she said.

But embodying Ah-jin took an unexpected toll. Kim revealed that the emotional whiplash from acting out Ah-jin's evil doings was so extreme, she experienced brief lapses in memory while filming.

“What really surprised me was that, at times, it felt like I’d actually lost my short-term memory. There are scenes I genuinely don’t remember at all. The situations and emotions were so intense and shocking. They say that when a person experiences something overwhelming, the mind can momentarily block out the memory. I feel like that’s what happened to me while working on this project," said Kim.

With two episodes left, Kim says the series is designed to linger.

“I hope it becomes a work that continues to spark curiosity even after it’s over, something that leaves you with countless questions. I know it’s not the kind of project that’s easy to rewatch, but even if you don’t go back to it, I’d love for viewers to keep wondering, ‘Why was this aspect of the character the way it was?’” asked Kim.

She added that the final stretch comes with its own nerves.

“I really hope people stay with us until the end. Of course, there are parts I’m genuinely worried about — after all, this is essentially the life story of a single character. I kept asking myself whether viewers would be able to maintain their focus all the way through," Kim said.

The series is one of Tving’s defining plays of the year, led by Hallyu star Kim and steered by Lee Eung-bok, the director of Netflix’s “Sweet Home” franchise and the K-drama classic “Guardian: The Lonely and Great God.”

“Dear X” also marks a milestone for Tving’s global ambitions: though the platform has yet to fully launch overseas, the series is among the streamer’s first titles rolled out internationally through branded hubs: on Disney+ Japan in November and HBO Max across Asia in October. Since then, the drama has surged to No. 1 on Disney+ Japan and become one of HBO Max’s most successful Asian titles across 17 markets in the Asia-Pacific region, including Southeast Asia, Taiwan and Hong Kong.

The final two episodes of “Dear X” premiere on Tving on Dec. 4.