The story is no longer just about Shin Hyun-heup. Besides Mr. Kim, now Kim Mei-sung sees the lines; it feels like no one is safe. Every time someone puts on the glasses, the truth ruins them. And let’s not forget Lee Gyu-jin—she has no line at all, and that’s somehow the scariest part.
These episodes make you question everything—who’s innocent, who’s hiding something, and whether seeing the truth is really a gift... or a curse.
Quick Drama Info
Drama: S Line (에스라인)
Network / Platform: Wavve
Premiere:11 July 2025
Aired On: Friday
Episodes Reviewed: Episode 3 & 4
Genres: Fantasy-thriller, Mystery, Coming-of-age
Based on: Webtoon S Line by kkomabi
Cast and Characters
Arin (as Shin Hyun-heup)
Lee Soo-hyuk (Han Ji-wook)
Lee Da-hee (as Lee Gyu-jin)
Episode 3: Who Can You Trust?
Episode 3 opens with Shin Hyun-heup rushing Kang Seon-ah to the hospital after she falls from the school rooftop right in front of her. The next day, the school staff wonders why the language teacher hasn't shown up.
At this point, no one knows the truth—that Seon-ah was pushed by the English teacher because she had been blackmailing him over an affair with a student.
Soon after, photos of the teacher’s relationship with the student leaked online, causing a massive scandal. Not long after that, the teacher is found dead in his car, with a note titled “Will” beside him. It looks like suicide, but when Han Ji-wook begins investigating, he discovers it was murder.
Meanwhile, Mr. Kim, another teacher at the school, finds a strange pair of glasses left on his desk. He asks Lee Gyu-jin if they belong to her, but she calmly replies, “Since they were on your desk, they must be yours,” adding, “They suit you. You should wear them.”
When Mr. Kim puts on the glasses, he starts seeing the red S Lines, just like Hyun-heup, Kang Seon-ah, and Helmet boy. But he notices something unsettling—Lee Gyu-jin has no line at all, which immediately makes her suspicious in his eyes.
Later, Mr. Kim uses the glasses and discovers that his brother-in-law is cheating on his sister. The truth breaks his sister’s heart and destroys her marriage, showing just how dangerous these glasses—and the power to see S Lines—can really be.
Overall, the introduction of Mr. Kim as a new “S Line seer” adds another layer. His discovery about his own family brings the drama closer to home and proves that once you start seeing the truth, you can’t unsee it. "In the end, Kim also destroyed something important because of what he saw through the S Line."
But the most chilling part? Lee Gyu-jin. She remains unreadable—calm, polite, and completely line-free. That’s what makes her terrifying.
Episode 4: The Teacher’s Mask Cracks
In Episode 4, Shin Hyun-heup finally tells Han Ji-wook about the mysterious glasses and the red S Lines—but he doesn’t believe her at first. Meanwhile, Kang Seon-ah remains in the hospital in critical condition after the rooftop incident.
After Mr. Kim, the glasses are found by Kim Mei-sung, another teacher from the same school. It’s starting to feel like the S Line glasses are circling around Hyun-heup’s school, passing from one person to another. What was once a rare curse only Hyun-heup could see is now spreading—more and more people are being drawn into its dark web.
On a brighter note, Shin Hyun-heup finally finds a job and starts forming friendships. They don’t think she’s weird. Instead, they genuinely enjoy spending time with her. For the first time in a while, Hyun-heup begins to feel a sense of belonging.
Let’s talk about the new owner of the S Line glasses—Kim Mei-sung. She’s a little strange, and she secretly has feelings for one of her colleagues: the music teacher. But one day, she sees his S Line connected to someone else. Jealousy takes over, and in a fit of rage, she kills him. Soon after, guilt and obsession consume her, and she ends up taking her own life—another victim of the S Line’s haunting curse.
Toward the end of the episode, Han Ji-wook finally puts on the glasses. What he sees stuns him—his own red S Lines are countless. This moment hints that Ji-wook’s past might be far darker and more complicated than anyone imagined.
Character Performances
Shin Hyun-heup (Arin): Her fear is raw, her isolation deeper. She's no longer just reacting—she’s starting to fight, but the red lines are suffocating.
Han Ji-wook (Lee Soo-hyuk): A silent protector or someone who's hiding more than he shows? His performance keeps us guessing.
Lee Gyu-jin (Lee Da-hee): Cold, elegant, dangerous. She commands every scene, and her lack of an S Line makes her even more terrifying.
Personal Note
S Line is becoming increasingly dangerous with every episode. The story continues to grow darker and more intense. It feels like the S Line glasses are choosing their next owner—and completely destroying their lives.
I’m really curious to see Han Ji-wook’s reaction. Things are just starting to heat up, and it’s only going to get wilder from here.
Final Thoughts
Episodes 3 and 4 of S Line deepen the mystery and expand the scope of the red thread curse. What started as one girl’s hidden burden is now a chilling chain reaction affecting multiple people at Hyun-heup’s school. With each new person who puts on the glasses, we see how dangerous the truth can be—especially when emotions like jealousy, betrayal, and guilt come into play.
From Mr. Kim's family falling apart to Kim Mei-sung's disturbing descent, the S Line is no longer just a symbol—it’s a trigger for destruction. And now that Han Ji-wook has seen his own tangled past through the glasses, the story is bound to spiral even further.
The tension is rising, and one thing’s clear: no one who sees the S Lines comes out unchanged.
Stay tuned—things are just getting started.
With every episode, S Line keeps pulling us deeper into its mystery. Who’s next? What will the glasses reveal? Don’t miss what’s coming next—it’s only going to get darker, wilder, and more intense. Stay tuned with us for more Kdrama Updates.
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