Chapter 8: Achilles' Heel
The undead were dangerously closing in on the three high school students, their green eyes gleaming with an unholy light, betraying a murderous rage and hunger.
A zombie lunged violently at Ken, its putrid claws ready to tear him apart in a single strike. However, with a quick and confident step, Ken recoiled with disconcerting ease, letting the monster's momentum throw it off balance under its own inertia.
The next second, his gaze hardened. His iron grip tightened on the fire extinguisher resting on his shoulder. In a flash, he leaned slightly forward and brought down the improvised weapon with crushing force onto the undead.
A sinister crack echoed. The cursed creature's skull shattered upon impact, violently flung backward in a geyser of black blood splattering across the floor.
No sooner had Ken eliminated the first one than another infected student—this one larger than the previous—threw itself at him once more.
But it was at that moment that Kim Seojun intervened. His iron rod sliced through the air like a sharp blade and struck with a fluid, precise motion onto the corpse's jaw. A crisp crack resounded: the jaw snapped clean under the pressure. The impact sent the undead staggering backward, mouth bloody, losing a few teeth in the process.
"I got it…" Kim thought, panting, sweat beading on his forehead.
Yet, just when he believed he had neutralized the undead, it rose again, staggering and growling with terrifying fury. Its broken jaw useless, it leapt furiously at the blond boy, eyes injected with rage, ready to tear him apart.
Caught by surprise, Kim lost his concentration. He was convinced he had already neutralized the creature. But the cursed one's lightning-fast counterattack caught him off guard and unbalanced him, hurling him brutally to the ground. He landed on his buttocks, helpless and at the monster's mercy.
Fortunately, it was precisely at that moment that Ken appeared behind the undead. With surgical precision, he slammed the fire extinguisher violently onto its neck. A sinister crack resonated, and the bone broke.
The creature collapsed immediately, hitting the ground like a rag doll at the two boys' feet.
Ken paused for a moment, then his red eyes, cold and merciless, fixed on Kim. He stared at him long and silently, as a heavy silence settled between them. Then, with icy detachment, he turned his gaze forward.
His voice finally broke the silence, sharp and laced with biting irritation:
"Stop hesitating."
He dropped the words into the blond boy's mind before moving off without waiting, throwing himself toward the approaching zombies to buy precious minutes.
Remaining on the ground, Kim followed his back with his eyes, each step taking Ken further away, a knot of conflicting emotions tightening in his chest.
The Demon King, meanwhile, remained relentless and clear-headed, showing remarkable composure despite the surrounding chaos. With each strike, the fire extinguisher cut through the air with unrelenting force. Despite its weight, he wielded it with disconcerting ease, felling multiple zombies in a single motion.
His attacks were fast, clean, surgical: each strike aimed at a vital point. Without a single unnecessary gesture, without the slightest hesitation, he moved gracefully in a deadly dance where speed and power intertwined with chilling precision, worthy of the greatest martial arts masters.
In barely a few seconds, a dozen corpses already lay at his feet.
Kim observed the scene briefly before lowering his eyes, hidden behind his fringe, lost in the turmoil of his thoughts.
"Am I doomed to remain forever in his shadow?" he wondered.
His dark gaze fell on the corpse of the undead at his feet. The body of the infected student lay cold, smeared with its own blood. He knew him… in fact, he knew everyone.
Ken's words echoed again in his mind, cold and unrelenting, and a wave of doubt washed over him.
***
When the undead attacked, Kim had hesitated for a moment. His arm had faltered, his strength diminished, and the trajectory of his strike had changed without him realizing it. Instead of aiming for the skull, his blow had struck the monster's jaw.
Moreover, seeing the infected student had awakened buried memories, destabilizing him completely. A minor distraction, certainly, but enough to put him in danger. If Ken hadn't intervened, it could have ended badly. Once again, Ken had just saved his life.
Even though the undead's jaw had been broken, no one really understood how the curse worked: did it transmit only through biting, or was a mere scratch enough? The system had only provided fragments of information, and no one was ready to test it on themselves.
In contrast, the Demon King showed no hesitation. He had already adapted; his gaze remained cold and resolute. He was ready to do anything to survive this hell.
Kim had known Ken for years—years of challenges and confrontations in various arenas—and knew that efficiency was his priority: wasting time with a useless rival, incapable of striking decisively at the crucial moment, was not his style. Yet, for him, killing the cursed ones came at a cost. Especially when they were comrades, even disfigured, even stripped of humanity.
For a hero, whatever the cause, it was still a murder. He had not fully recovered from the first one and could not bring himself to abandon them.
He lowered his eyes and looked at his hand, still trembling.
"Don't hesitate, huh?" he murmured. Then, quieter, like a question he dared not voice: Is it the only way? Is there really no way to bring them back?
***
"Kim…"
"Kim!"
Hanna approached, still on the ground, calling his name. But the blond boy didn't immediately respond, lost in thought. Only when her gentle hands touched his cheek did he return to reality. Her blue eyes, still wet with tears and full of concern, scrutinized his face intently.
"Are… you okay?" she stammered, voice trembling.
At that moment, something in Kim wavered. His gaze brightened. Gently placing his hand on hers, meeting her worried face, all his doubts seemed to vanish.
"Yes… I must not hesitate. For her!" he thought inwardly, eyes shining with newfound determination.
"Hanna, forgive me."
The girl tilted her head, puzzled. She didn't fully understand, but instinctively felt that something had changed in him.
"I almost broke my promise…" Kim murmured in a serious tone.
He gently withdrew his hand, straightened up, and picked up the iron rod beside him, back turned to her. Hanna watched this sudden change, puzzled.
Even if I have to kill people or monsters, there's no debate. I will protect her, no matter the cost, he thought, face dark, jaw clenched.
Without turning, he called Jae-sung, the student close enough to hear, who quickly approached.
"Take Hanna and get her through the door. In the meantime, I'll fight the zombies with Ken to buy you time to evacuate."
The girl's already worried face darkened even further. With a breath, she cried out in anger:
"You're not serious, Kim? Have you lost your mind…?"
But Kim interrupted her in a deep voice:
"It's the only solution. Only Ken and I can hold here. If we don't buy time… we're all lost."
He paused for a moment, then resumed calmly:
"Don't argue, Hanna. These walking corpses can't stop me. After all, I am the captain of the kendo club."
He placed his hands on his hips, gave a brief smile, then, in a flash, his expression returned to serious. Accompanied by a slight sigh, he added in a calmer tone:
"Don't be afraid. Neither Ken nor I will face the gigantic creature at the back alone. I haven't gone mad… yet."
The girl's eyes grew serious again, lost in deep thought. Hanna finally seemed to understand the situation, aware that every second counted.
Then, in an almost playful tone, Kim added, trying to lighten the mood and reassure her:
"And you know, nothing will happen to me as long as I team up with that monster."
He pointed to Ken with a small mischievous smile and a casual gesture. In front of them, Ken was taking down the undead one by one, wielding a six-kilogram fire extinguisher with terrifying ease, as if its weight meant nothing.
"Even if he acts cocky, I know he needs me…" Kim added, shrugging, voice pouty. "And I also know that arrogant demon bastard will never admit it… seriously, you can't find anyone more stubborn than him."
Despite his attempts to reassure her, Hanna didn't seem convinced. She noticed his hand trembling as it gripped the iron rod tightly.
A stark contrast to the calm he tried to project, his gaze still fixed on her, concern visible in his eyes.
Kim scratched his head nonchalantly, aware that he wasn't putting anyone—especially not Hanna, who knew him better than anyone—at risk.
What a poor performance for an actor incapable of reassuring his friends… he thought with a hint of irony.
The hero's face returned to seriousness and resolve. Gripping the iron rod firmly, he turned and declared in a loud voice:
"Jae-sung, I'm entrusting Hanna to you for a moment. I'll come back for her later."
The boy nodded timidly, grabbed Hanna's hand, and guided her toward the door, running. She followed, her hurried steps echoing in the carriage, but her eyes remained fixed on Kim. The farther she went, the more his figure receded, slowly disappearing, surrounded by the undead.
"Please… don't… DON'T DIE!" she shouted, voice choked with fear, heart pounding.
"Of course not!" Kim murmured to himself, quickly throwing himself into the fray.
***
Meanwhile, Ken continued eliminating the zombies one by one. Their speed was slow, but the real problem lay in their number, which seemed infinite. No matter how many he took down, new ones appeared endlessly, giving him almost no respite.
And the worst… was that immense three-and-a-half-meter creature, the Corpse King. Its glowing green eyes fixed on him in the darkness, motionless for several minutes, as if judging him. It let its puppets fight in its place, without lifting a finger.
The Corpse King was unlike any beasts or creatures Ken had known. It was not guided solely by instinct; it exuded a cold, calculating intelligence, terrifying, chilling Ken to the bone. Its eyes… they were not the gaze of a mere animal.
"Not only terrifying… but intelligent. As if that weren't enough…" Ken breathed, a wry smile on his lips, sweat beading on his face.
Despite growing fatigue, Ken continued massacring the undead relentlessly. But his goal went far beyond buying time. Had he wanted, he would already be on the other side of the door, safe.
No!
He was seeking information. Understanding his opponent, analyzing its mechanics, finding weak points if possible… even the smallest piece of information could save his life in case a fight became inevitable.
The more he faced the undead and observed the Corpse King, the more questions flooded his mind.
Why isn't it attacking? It could crush us in a single motion. Or… is it afraid? No. It is dominant. Then why? Perhaps it's playing… or avoiding risk?
"…Wait… what is that…"
Suddenly, Ken's eyes widened. He had found what he was looking for. After a few seconds of observation, he spotted what seemed to be a flaw in the monster's impenetrable armor.
All its fluorescent green veins converged in vague patterns toward a specific point, at the center of its chest. Its exoskeleton did not cover this area, revealing something resembling a greenish heart, pulsing and casting a sickly glow over its asphalt-black skin.
Ken Jiheon gave a wicked smile. "So… this is your Achilles' heel, you filthy beast."
Seeing this, he thought that if he could get close enough to the Corpse King, he would have a better chance to strike its weak point and kill it. But the idea vanished as quickly as it came. Approaching meant walking straight into the arms of death, and his current weapon did not seem suitable for such piercing work.
He glanced at his fire extinguisher, grimaced for a moment, then resumed his thoughts.
Despite its weak point, the monster compensated with a very tough bony armor, troublesome, which would render most of Ken's attacks ineffective, not to mention its fangs and long, scythe-like claws.
And the worst part of all: its ability to control the undead. It corrupted the living, turning them into puppets used as shields and weapons, infecting others in turn.
To reach it, he would have to annihilate the horde forming its inner guard—a titanic task. And during that time, nothing would prevent the Corpse King from crushing him in a single blow. Ken shook his head, dismissing the thought. It would be a one-way ticket to "game over."
The best plan would be to separate the monster from its puppets to face it directly. But even then, a single strike from the powerful creature would be enough to send him to join its ancestors in the afterlife.
Ultimately, Ken forced himself to admit the truth: the best choice remained to follow the system's instructions:
Either reach the required number by massacring the majority of students until only two survivors remained.
Or simply survive until morning.