Korean star siblings Sang Heon Lee and Gia Kim: The rise of Netflix’s breakout power duo, XO Kitty and beyond

There’s a certain kind of teen drama twist audiences expect, love triangles, betrayals, secret identities. But XO, Kitty has a more unexpected reveal tucked behind the fiction: Sang Heon Lee, who plays the caustic, yet soft-hearted Minho, and Gia Kim, who portrays the outspoken Yuri, are siblings in real life.

And unlike most plot twists, this one just keeps getting better.

Perhaps, that's what makes their story compelling. Apart from watching them be on screen together, it's how their real relationship seeps into everything: The promos, the interviews, the Instagram comments, the red carpets, even the way they talk about each other. Oddly refreshing, and yet wholesome, as fans would agree.

The banter and the care

She teases him under an Instagram photo from set: “Sister walks in…”

He replies without hesitation: “Get out.”

Then, on another post, the tone flips, hugs, encouragement, and soft, familiar support. There are selfies, playful jabs, and moments of genuine pride that slip through the noise of promotion cycles and press tours. And then there are the bigger stages: premieres, fashion weeks, and even an Oscars appearance, where the teasing pauses but the bond remains visible. One sibling is always hyping the other on the Instagram, expressing pride.

This little balance between love and banter, is what fans keep returning to. And so, while XO, Kitty gives only brief glimpses of Minho and Yuri together, the real-life version of Sang Heon Lee and Gia Kim offers a sibling rhythm that doesn’t need a script.

Seoul, Hong Kong and everything in between

Long before global fandoms and Netflix charts, the two were just siblings growing up side by side in Hong Kong after their family relocated for their father’s work in construction. They attended Island School, sharing the same classrooms and environment, long before they ever shared a screen.

Lee later pursued Drama at the University of Northampton in England, building his foundation through modelling and smaller roles while quietly shaping an acting career. After graduating, he returned to South Korea to complete his mandatory military service. Gia, meanwhile, carved her own path into acting, developing independently until their professional worlds eventually collided.

In hindsight, that convergence feels almost inevitable, but at the time, it wasn’t.

The auditions

Ironically, it was Gia who nudged him toward XO, Kitty.

“She saw an Instagram post and told me to look at the role. I ignored her as a younger brother,” Lee recalled on The Daebak Show. “Then, three days before the deadline, she texted me and said, ‘Please tell me you sent your tape.’”

He admitted he had never submitted an audition tape before. Gia even sent him an example to guide him through it. “It’s not that I didn’t have the passion,” he said. “But I wondered how I could even land this role, it was on Netflix.”

Still, he went for it. And he got the part.

Lee has also spoken about how his interest in acting began in high school, where he initially leaned toward choreography before being steered toward drama by a career counsellor, a redirection that shaped his future.

Separate paths, and shared momentum

From there, everything fell into place. Lee became Minho, Gia became Yuri, and suddenly the siblings began to share a professional universe. Since then, Lee has appeared in projects such as Gran Turismo (2023) and the Filipino series Secret Ingredient (2024), steadily expanding his international footprint. Apart from Minho’s emotional complexity, that goes far beyond a yearning romantic lead in in XO, Kitty, (those tears will haunt fans for a while), Lee has already shown his range through more intense roles, as Secret Ingredient shows.

Both the siblings are slowly cementing their popularity with fervent fandoms: Lee, unleashed a different, raw and vulnerable side to himself in the latest Season of XO Kitty, playing the role of a teenager, burdened with thoughts of never being enough, while Gia proved that Yuri was more than just romance: She was the fashion star, too, who, also was trying to help her friend group reunite.

She has also turned Yuri into something more than her sharp exterior suggests. Across recent seasons, the character has revealed a softer emotional core, particularly in subtle gestures, like trying to reconcile with a difficult family, or the compulsion to part with a pair of boots that once carried her through the worst summer of her life.

A lot of the success of XO, Kitty does stem from the duo, apart from the rest of the stellar cast, of course. The show has since come into its own, building a dedicated fandom that extends well beyond its To All the Boys I've Loved Before roots. With growing calls for a fourth season, anticipation continues to build around what’s next.

There is also increasing interest in seeing Sang Heon Lee and Gia Kim expand into K-drama and other international projects. As many fans have put it, they would be “absolutely lethal.”

The star power of the duo

Off-screen, their visibility as a duo has only intensified interest. From fashion events to interviews, and even appearances during awards season and international premieres, Sang Heon Lee and Gia Kim have become a familiar pairing in entertainment spaces where sibling duos are rare.

Earlier this year, they attended Paris Fashion Week together. Gia later reflected on the moment in an Instagram post:

“Very short but very sweet weekend reunion in Paris avec mon frère,” she wrote. “It may seem as though actors’ lives are always glamorous. They are not. Yes, we share the glamorous parts, but it’s one day out of 365—it’s mostly work.”

Why audiences are invested in them

Gia, who made a different appearance on the Daebak show, made a rather emotional comment once: “One of the biggest blessings of Xo Kitty, is how it drew me and my brother closer. We are very different people, and it forced us to communicate. At the beginning, there were some bumps, as he was being so annoying, but overall, beautiful things came out of it, and now I feel every time I spend time with him, the days and moments, I can confidently say, I am happy if I die now, are the moments after I spend time with my brother. If I have a really good day with him at the park, then I am like I could die now.”

The clips went viral on social media, perhaps for good reason, with fans demanding to see more of the duo. The rhythm exists in their easy jokes, quick comebacks, and that unmistakable sibling shorthand that doesn’t need explanation. “They’re just so wholesome to watch,” one comment read.

The closeness exists in the margins, in interviews, casual comments, and offhand jokes like Lee reacting to a fan compliment, “If Gia compliments you, you tell her to shut up.” He replies, almost as an afterthought, “It comes from a place of love.”

The truth is, audiences are drawn to what isn't quite written in the script. A scripted romance can be a thrilling escape, but there’s something equally compelling about watching two siblings stand by each other through every high and low, an easy siblinghood that offers its own kind of comfort and reassurance.

 And for fans, that might be the most compelling storyline of all.