We are all dead.

works as a firefighter, survivor.

Yoon Yi Sak is Nam On Cho's best friend. Their friendship is one of those warm, living threads that doesn't break even in the midst of a nightmare. And Sak knows how to lighten the mood: she can kindly tease On Jo, make her laugh just when she feels she has no strength left, and without unnecessary grandiloquence, she lets her know, "I'm here for you, you're not alone." Their interactions are full of simple, recognizable teenage details—they share what's on their minds (for example, On Jo tells her he likes Lee Soo Hyuk), they chat about trivial things, and behind this lightheartedness lies a very serious support system: each knows that in a critical situation, the other won't turn away.

Kim Chul Soo is a guy from the same school as Min Eun Ji, who has had a crush on Min Eun Ji for a long time.

Before the nightmare of the infection, he lived under constant pressure: like Eun-ji, he was bullied, and Gwi-nam's gang forced him to do humiliating things—and this made him feel trapped and powerless. He was deeply troubled by his inability to openly stand up for Eun-ji: fear for her and the shame of his own silence seemed to weigh heavily on him. His support back then was quiet and almost unnoticeable—he simply tried to be there when he saw she was in deep trouble, and with a glance or a few short words, he would let her know, "I don't think you're to blame, I see how hard it is for you."

Min Eun-ji, a student at Hyosan High School who didn't make it through grades 2-5, was cruelly bullied by her classmates, and blackmailed by Yoon Gwi-nam. This left her feeling trapped and completely alone: ​​at school, she felt like she wasn't even human, and any attempts to cling to something familiar were shattered by the ridicule of others.

Park Sun-hwa, the English teacher, is also the homeroom teacher for grades 2–5. She's not one to bully students with authority; rather, she tries to listen to her students and notice if something is off. For example, she worries when someone disappears from the radar or looks exhausted, and doesn't dismiss warning signs. Her lessons don't degenerate into dry memorization of rules; she strives to speak to the students in a way that makes language feel alive, not just another burden on the schedule.

Despite her gentle nature, she's quick to pull herself together: when danger looms around her, there's no fuss, only a clear, calm composure—as if she's shouldering an invisible but heavy burden: ensuring at least some of the kids survive. She's the kind of adult who, in a critical moment, doesn't hide behind official regulations, but instead seeks to immediately protect those for whom she feels responsible. For the students, she gradually becomes a point of support—not a menacing overseer, but someone who, even when things are scary, doesn't give up and reminds them to stick together. At first, she sticks with the kids, then they split up.

Park Hee-soo is a student in grades 2-5 at Hyosan High School. She's quiet, tries to keep a low profile, and for a long time, almost no one at school suspects she's pregnant: she cleverly conceals her condition behind voluminous clothes. For her, this pregnancy is both a vulnerability and a focal point for her most important decisions: she must think not only about herself but also about protecting the baby.

In the usual school routine, she seems to be trying to blend into the background—to avoid attention, avoid arguments, and conserve her energy. Yet, her actions reveal her commitment to doing what's best for her child in the future: even in small things, she chooses a path of caution and care, as if every step now passes through a filter of "will it be safe?" During and before the apocalypse, she doesn't stay with the kids; she runs home, but her path is blocked by zombies, forcing her to take refuge in various stalls.

Jung Min-jae is also serious about training—for him, shooting isn't just an after-school activity, but a discipline- and precision-driven endeavor, so he and Ha-ri are on the same wavelength: they understand without further ado how to keep their distance, when it's time to draw the bow, and when it's best to just keep quiet and focus.

Min-jae isn't the type to draw attention to himself—he's rather quiet, collected, and even-tempered. This creates a balance with the blunt Ha-ri: she sometimes flares up and makes barbs, but he doesn't respond to her bluntness, simply calmly returning the conversation to the workflow, as if he's sorting everything out again, like arrows in a quiver. At the same time, he genuinely cares about the team and how well they're prepared—it's clear that it's important to him not to let down those who rely on him.

They're riding together on that same bus returning to Hyosan from training: at first, both are immersed in their thoughts about the exercises, about what didn't work out today, what little things need to be worked on, and only gradually begin to notice that the world around them seems to be gradually losing its usual rhythm.

At first, Jang Ha-ri isn't even among the kids hiding in the school—she shows up later. When everything starts to fall apart, she's riding the bus with her archery teammate, returning to Hyesan from practice. For her, the trip initially seems like a normal day—the usual route, thoughts about shooting, how she did during the drills, maybe a little irritation over small details or fatigue. But along the way, they gradually begin to notice that something is wrong, and it's this moment—when familiar reality slowly begins to crack—that dramatically changes her routine.

Yang Dae-su is a student in Class 2-5 at Hyosan High School. He's in the school choir and loves singing—it brings him joy and a way to brighten up his gray days. Dae-su often jokes, trying to lighten the mood, as if he wants everyone around him to stop frowning. Behind this cheerful demeanor, however, one can see how important it is to him to be accepted and not rejected—he reaches out for friendship, tries to be helpful, and doesn't hide his emotions: if he's sad or scared, he doesn't hide it tightly.

Lim Na-young is a student in grades 2-5 at Hyosan High School. At school, she has built a thorny barrier around herself: she speaks sharply, acts as if she's prepared to defend herself against anything anyone says, and loudly proclaims that she doesn't need anyone—as if showing even the slightest bit of vulnerability would immediately be taken advantage of. Behind this bravado lies a fear of being abandoned and unwanted: it's as if she's cultivated anger as a defense, so no one will see how anxious she truly is.

In a disaster, her bluntness sometimes works like an emergency button: when the group freezes in fear, her loud voice and forcefulness force them to wake up and move. She knows how to firmly stem panic, seize control in moments where hesitation is dangerous—and in such moments, her usual aggression turns into a rough but necessary force. But when it's not pressure that matters, but negotiation, this same tactic fails: she loses her temper, gets angry when she's not heard, and this makes her feel even more lonely.

Gradually, her storyline reveals how difficult it is for her to learn to trust and accept help: every time she finally takes a step toward the group—not commanding, but simply supporting someone quietly, without shouting—it feels like a small but real turning point. Her journey is about how someone accustomed to defending themselves with attack slowly learns that sticking together doesn't mean becoming weaker.

Jeong Byung-chan is a student in classes 2-5 at Hyosan High School. In everyday school life, he's not the type to make a big splash: he doesn't push for leadership or start loud conversations, often hanging back from the most prominent groups, as if deliberately choosing a position where he can quietly observe everything from the sidelines. He doesn't give the impression of living life at full volume; he's more of a quiet presence: he can listen for long periods, memorize how relationships develop between people, and notice things others miss in the hustle and bustle.

He has that quiet reliability: he doesn't make heroic promises, but if he says he'll help, he'll likely follow through, and without unnecessary pretense. Sometimes he seems a little shy, or as if constantly weighing whether to engage in conversation, but behind this reserve lies a talent for support: in a critical moment, he's able to pull himself together faster than expected and do what others lack the fortitude to do.

When chaos erupts, his quiet composure unexpectedly proves valuable: he doesn't waste energy panicking, but instead tries to grasp the essence of what's happening and find a practical solution—whether it's figuring out how to block a door with improvised means, or simply reminding those completely at a loss of something important and simple (like bringing water or staying close to those who know the building's layout). He doesn't seek recognition for his actions and sometimes even seems embarrassed when someone openly thanks him—as if helping isn't a heroic feat for him, but simply a natural reaction when someone nearby needs help.

His journey through the series is made up of small but meaningful choices: step by step, he learns not to hide his care behind a mask of indifference, but to allow himself to be involved—and it is this gradual willingness to take responsibility, while remaining a simple and sincere guy, that makes him an important part of the overall survival story of Class 2-5.

Park Mi-jin is a student in Class 2-5 at Hyosan High School. At first, she seems to deliberately put her most piercing face forward: harsh words, mocking intonations, a demonstrative indifference—as if she's decided in advance that she won't get attached or trust anyone, and that the best defense is to keep people at arm's length. She exudes a stubborn, almost fierce independence: she loudly declares that she can handle things on her own, and sometimes deliberately pushes away help from others, as if the very idea of ​​leaning on someone is a sign of weakness. But when the going gets tough, what she's so carefully hidden begins to shine through this veneer: an ability to genuinely care for others and a willingness to risk herself for those around her. She doesn't make pompous speeches or play the heroine—her concern comes in the form of harsh but life-saving decisions: stopping someone who's panicking and ruining the overall plan, tugging someone's sleeve just in time to avoid a blow, standing where it's scary, simply because there's no one else to do it. Two forces coexist within her: one that pushes back and defends, the other that, despite everything, shoulders the burden and watches everyone's back. And as trials mount, her harshness increasingly reveals itself not as malice, but as a way to maintain balance in a crumbling world: she makes crude jokes to prevent fear from paralyzing the group, raises her voice to reach someone through the panic, and then, when the danger has passed, seems to shyly hide the very vulnerability she had just so desperately concealed. Her journey is a slow, uneven, but genuine maturation: from the desire to seem impenetrable to the ability to recognize that even strong people can be afraid and that asking for support is not a weakness, but part of what helps you survive.

Kim Min-ji is a student in grades 2-5 at Hyosan High School. She's not one to seek the spotlight, and in the typical school routine, she tends to stay on the periphery: she doesn't start conflicts, doesn't strive to be the life of the party, but she doesn't hide completely in the shadows either—she simply lives at her own pace and maintains her personal boundaries. She has a quiet, unobtrusive kindness: she doesn't throw out loud words of support, but helps in truly small but meaningful ways—she can discreetly share notes, suggest where to find needed information, or simply be there when someone needs some peace and quiet, not just to be left alone. She's observant and not given to hasty conclusions: before forming an opinion about a person or a situation, she gathers details and gives herself time to think things through. This allows her to avoid mass panic in the chaos of the apocalypse, instead trying to keep a cool head and rely on what she knows. Despite her gentle nature, she has an inner composure: when circumstances demand decisive action, she doesn't crumble, but finds the strength to act—perhaps without showy gestures, but consistently and reliably. Her strength lies in her constancy and ability to maintain her humanity even when the world around her seems to be deliberately testing people to breaking point: she remembers the little things that sustain life (warm clothes, water, a safe corner), and what people sometimes need most—a simple nod and a "I hear you."

Yoon Gwi-nam is a student at Hyesan High School, not in class 2-5. He has a tough, prickly personality and a reputation as a bully, which at first is easily misinterpreted as anything other than aggression. One of his most contradictory traits is his stubborn, almost animalistic will to survive: when the familiar order collapses around him, he wastes no time on doubts, but acts instinctively, relying on strength and brutality, as if the world itself has become a ring where the fastest and toughest survive. Despite his roughness, he reveals an unexpected tenacity of mind: he quickly reads the balance of power, senses weakness, and calculates how to turn the situation to his advantage, making him a dangerous and unpredictable player even in chaos. He possesses a dark, selfish energy—he makes no secret of his own self-interest and doesn't feign nobility, but it's precisely this frank honesty about his own motives that sometimes makes his actions easier to understand than the ostentatious virtue of others. And for all his cruelty, Gwi-nam is capable of flashes of strange, angular affection: where he senses even a shred of duty or connection, even if it stems from an old grudge or a forced alliance, he can unexpectedly display loyalty and take risks—not out of lofty ideals, but because for him, it's a matter of personal honor, defined in his own way. He combines cruelty and stubbornness, cold calculation and flashes of that very devotion that resonates not in fine words, but in a willingness to stand firm to the end where no one expects a shred of humanity from him.

Han Kyung-soo is a student at Hyosan High School, a boy who, from the very first moments of hardship, tries not to let fear and despair take over. One of his most noticeable traits is his genuine, active kindness: he doesn't wait for someone to ask for help, but seeks out those in need and tries to lend a shoulder to lean on—whether it's a supportive word when someone is on the verge of a breakdown, or simple but vital help like finding shelter or water. He lacks ostentatious bravado, but possesses a quiet, stubborn resilience: when others give up, he continues to do at least something, even if it's small things that gradually build up a chance for salvation. He knows how to truly listen—not just for show, but in a way that makes people feel: their pain and fear are not devalued, they are heard. Despite his gentleness, Gyeong-soo is capable of showing firmness when it comes to protecting those weaker—and then, behind his calm, a surprising determination emerges that refuses to retreat in the face of danger. His humanity doesn't turn into weakness: he soberly assesses risks, doesn't rush into reckless adventures, but also doesn't hide behind others, choosing the path where he can help without destroying himself. It is this mixture of compassion, patience, and calm responsibility that makes him someone with whom, even in the most terrible chaos, it becomes a little easier to breathe—because he doesn't promise the impossible, but simply stays close and does what he can.

Choi Nam-ra is a student and class representative for classes 2-5 at Hyosan High School. From the start, she maintains aloofness: reserved and extremely collected, as if she's built an invisible barrier around herself that she rarely lets anyone cross—and this reserve is initially easily read as arrogance. One of her strongest traits is her ironclad mental discipline: accustomed to relying on logic and clear rules, she doesn't get lost in the chaos of the apocalypse, but methodically breaks down the situation into its component parts and seeks the most rational solution. Despite her outward coldness, she harbors a deep sense of responsibility: her position as class representative isn't just a formality for her, but an internal obligation to look after her class, and even as the world collapses, she instinctively tries to maintain some kind of structure and order. Nam-Ra is observant down to the last detail—she notices subtle changes in people and surroundings, often being the first to spot a threat or realize a plan is about to go wrong. Over time, another side of her usual defense begins to emerge: an ability to bond with and protect those she begins to trust, and she does this without grand pronouncements, through concrete actions and a willingness to shoulder some of the burden. She combines sternness with hidden loyalty, and her ability to resist panic and stay the course even when the ground is slipping from under her gradually transforms her restraint into a pillar of strength that, in extreme situations, proves no less important than open courage.

Lee Soo Hyuk is a student at Hyosan High School, a man with noticeable physical strength and a certain composure that immediately inspires a modicum of confidence in those around him in extreme situations. One of his most striking traits is his willingness to take on dangerous work without further ado: he doesn't waste time on lengthy debates when something urgent needs to be done, and he's the first to go to the most dangerous places, as if he's already committed to being a shield for others. Despite his brutal composure, he's not without sensitivity: he knows how to spot someone on the brink of a breakdown and support them without pompous speeches—with a quick action or a few simple, firm words that make the person breathe a little easier. He's straightforward—he doesn't shy away from difficult conversations or hide his concerns, but at the same time, he doesn't pressure others and respects their boundaries, leaving room for everyone to make their own decisions. He possesses a rare combination of power and self-control: even when the adrenaline is pumping and chaos reigns all around, he maintains control, refusing to let anger or fear take over, and channeling his energy into focused protection of those around him. This blend of strength, composure, and quiet caring makes him the kind of person people instinctively count on in a disaster, even if no one says so out loud.

Nam On-jo is a student in grades 2-5 at Hyosan High School. From the first anxious moments, she displays a rare composure for such a young age: instead of giving in to panic, she methodically assesses the situation and tries to plan safe steps for herself and those around her. One of her most noticeable traits is a deep, active empathy: she doesn't limit herself to words of support, but immediately seeks out ways to truly help—whether it's caring for those who are weakened or trying to find a way out where others see only a dead end. Despite her gentleness and sensitivity, she can also be firm: when it comes to defending something important or protecting someone, a calm steadfastness awakens within her, and she clearly sets boundaries, not wasting time on empty arguments. On-Jo is observant—she notices details that are easily missed in the chaos and is able to piece them together into a coherent picture, often finding herself the first to spot a threat or identify a chance for salvation. She combines warmth and inner resilience: even when her strength is exhausted and she's terrified to the point of trembling, she finds the strength to never give up and continue to act for those who need support.

Lee Jong-sang is a student in Class 2-5 at Hyosan High School. At first glance, he appears to be an ordinary high school student, whose everyday life revolves around studies, family, and friendships. However, from the very first anxious moments, a rare inner composure emerges within him: when chaos mounts around him, he doesn't dissolve into panic, but rather switches to a cold, calculating mode, quickly sifting through what's truly important and what's merely wasting precious seconds. One of his strongest traits is his ability to take responsibility, even when he's scared: he doesn't wait for someone else to figure out how to save himself, but rather formulates a plan and takes the riskiest route first, covering for everyone else. Beneath his outward resolve, however, lies a warm, almost caring concern for his loved ones—he remembers the little things that matter to those he trusts, and in the darkest moments, he knows how to say just the right words that restore a person's strength to move forward. He's resourceful: in critical situations, he instantly notices details that others miss—be it an emergency exit, a suitable protective item, or a way to outsmart danger by exploiting the situation itself. And despite his willingness to plunge into the thick of things, he remains humanly vulnerable: he doesn't hide his grief when he loses friends, and he doesn't pretend it doesn't hurt. This honesty makes his support especially genuine, without pathos or empty promises. Ultimately, it's the combination of courage, resourcefulness, and genuine affection for people that makes him someone people involuntarily look to for support in times of disaster.