What Is "S Line," the K-Drama Behind the Red Lines All Over Your Feed?

By now, you’ve probably seen it: memes of red lines floating above people’s heads, usually linking them to someone else—sometimes an ex, sometimes a crush, and often, someone completely unexpected. If you've been confused about what these red lines mean and why they’ve taken over your feed, allow us to introduce S Line, the buzzy K-drama driving one of the internet’s latest viral trends.

S Line centers on a peculiar phenomenon: thin, glowing red lines that suddenly start appearing above people’s heads. These lines link individuals who’ve had sexual relations—no matter how secret, awkward, or long-forgotten. Needless to say, chaos ensues.

Leading the cast is Lee Soo Hyuk as Han Ji-wook, a sharp and striking detective determined to uncover the truth behind the S Lines. Lee Da Hee plays Gyu Jin, a high school teacher whose quirks make her stand out in a school turned upside-down by the phenomenon. Rounding out the core trio is Arin as Hyun Heup, a high school student who’s been able to see the lines since birth, long before anyone else could.

More than just a high-concept romance or mystery, S Line leans into its provocative premise to explore themes of intimacy, secrecy, and the ways people connect—or disconnect—from each other. It’s no surprise that the drama made waves internationally, becoming the only Korean series selected to compete at Canneseries 2025. The show’s premiere at the Lumière Grand Theatre reportedly ended with a standing ovation.

The concept of the red lines has quickly taken on a life of its own online. Many users have embraced the trend with playful creativity—drawing imaginary links to celebrity crushes or posting tongue-in-cheek memes where all their S Lines lead to a bed or between fictional characters. Some have even used the visual as a way to joke about exes or past entanglements, turning a provocative premise into social media fodder.

But not all responses have been lighthearted. Some netizens have voiced discomfort over how casually the trend treats the show’s sensitive subject matter. Critics argue that many people are participating without fully understanding the implications, with some expressing concern over privacy, digital footprints, and the potential misuse of the meme, especially when involving minors, strangers, or public figures. 

The contrast between the drama’s nuanced themes and the viral reaction has opened up conversations around context, consent, and responsible content sharing.

In South Korea, S Line is available to stream on the Wavve app, with the first two episodes dropped on July 11, 2025. While there's no confirmation yet on which global platforms will pick it up, fans are crossing their fingers for an official release on local streaming channels.