Day 41. 8:00 AM.
Class F assembled in the academy courtyard, fifteen students in matching training uniforms, trying to hide their nervousness behind forced bravado. Two instructors—Jung Min-seo and a middle-aged man named Instructor Cho—checked equipment and reviewed safety protocols.
Han Sera stood near the back of the group, her new combat sword secured at her hip, hidden supplies distributed in concealed pockets. She'd slept three hours and felt simultaneously exhausted and hyper-alert.
"Listen up!" Instructor Cho called out. "We'll be entering Dungeon C-47 at nine AM sharp. The route is straightforward—in through the main gate, follow the cleared path to Safe Zone Beta at the 300-meter mark, observe dungeon ecology, then extract. Total time: four hours. Questions?"
A student raised his hand. "What if we encounter monsters?"
"You won't. The path is cleared daily by Hunter Association teams. Any monsters in the area are low-level and will avoid groups our size." Cho's tone suggested the question was stupid. "This is observation only. No combat. Understood?"
Murmurs of understanding. Sera said nothing, her eyes scanning the instructors' body language. They seemed relaxed. Confident. Completely unprepared for what was coming.
*Watch the instructors' body language*, the janitor had said. *If they seem nervous, be ready.*
They weren't nervous. Which somehow made Sera more nervous.
She spotted him then—Kim Soo-hyun, the janitor, cleaning windows on the administrative building overlooking the courtyard. To anyone else, he was invisible. Just another maintenance worker.
But Sera saw the way he positioned himself for a clear view of the assembly. Saw how his cleaning movements had paused. How his attention was focused on Class F despite appearing to work.
He was watching. Just like he'd promised.
*If things go catastrophically wrong*, she remembered, *he'll intervene.*
The thought should have been comforting. Instead, it reminded her how dangerous this really was.
At 8:47 AM, Vice Principal Kwon appeared, tablet in hand. "Instructor Jung, Instructor Cho. A word."
The instructors moved aside. Sera couldn't hear the conversation, but she saw Kwon's expression—concerned, questioning. Saw Jung shaking her head, gesturing to official documents. Saw Cho looking annoyed at the delay.
Kwon wasn't satisfied with whatever answers he was getting.
*He knows something's wrong*, Sera realized. *But he can't stop it without evidence.*
At 8:55 AM, the discussion ended. Kwon looked frustrated but stepped back. The practical would proceed as scheduled.
"Mount up!" Cho called. "We leave in five minutes!"
Sera fell in line with her classmates, her heart pounding. In six and a half hours, everything would change.
She was as ready as she'd ever be.
---
9:17 AM. Dungeon C-47 entrance.
The portal shimmered with an oily, purple-green light that made Sera's stomach turn. She'd seen dungeon gates before—everyone had—but entering one was completely different from seeing it on news reports.
"Stay in formation!" Jung commanded as they passed through.
The transition was disorienting. One moment, Seoul alley. Next moment, twisted cave system with walls that seemed to pulse with bioluminescent fungi. The air was thick, humid, smelling of earth and something else—something rotten underneath.
**[DUNGEON ENTERED]**
**[Dungeon C-47: Gwanak Corruption Cave]**
**[Recommended Level: C-Rank]**
**[Current Corruption Level: 47% above baseline]**
**[WARNING: Environmental hazards detected]**
Sera blinked. She'd never received System messages before. Was this because of her improved rank? Or because the dungeon was more dangerous than the instructors realized?
"Stay close," Min-ji whispered next to her. "This place feels wrong."
She wasn't wrong. The dungeon felt... sick. Like something was fundamentally corrupted about the space itself.
They moved through the cleared path, boots splashing in shallow puddles of something that definitely wasn't water. The instructors led confidently, pointing out different types of fungi, explaining dungeon ecosystem basics, completely oblivious to the wrongness permeating everything.
At 10:43 AM, they reached the first safe checkpoint. No incidents. No monster encounters. Everything exactly as the instructors expected.
Sera's tension only increased. *It's too quiet*, she thought. *Where are the ambient dungeon creatures? Even cleared paths usually have some wildlife.*
By noon, they'd covered 250 meters and stopped for lunch in a cleared chamber. Students relaxed, eating packed meals and joking nervously. The instructors consulted their route map.
"Fifty more meters to Safe Zone Beta," Jung announced. "We'll rest there for an hour, then head back. See? Completely routine."
*Two and a half hours until 2:30 PM*, Sera calculated. *Two and a half hours until everything goes wrong.*
She picked at her food, unable to eat. Across the chamber, she noticed a few other students also seemed uneasy—not eating, scanning the shadows, gripping weapons they weren't supposed to need.
*Trust your instincts*, the janitor had said. *If something feels wrong, it probably is.*
At 12:47 PM, they resumed the march. Fifty meters to Safe Zone Beta.
The path narrowed. The bioluminescent fungi grew dimmer. The air grew thicker, harder to breathe.
And then, at 1:15 PM, they arrived.
Safe Zone Beta was a large natural cavern with high ceilings and multiple exits. Hunter Association equipment was stationed throughout—monitoring devices, emergency medical supplies, communication relays. Everything you'd need for a safe training environment.
"Excellent!" Cho declared. "Everyone find a spot to sit. We'll spend the next hour discussing dungeon navigation theory. After that, we head back to the surface."
Students scattered throughout the cavern, claiming spots against walls or near equipment. Sera positioned herself near the rear, exactly as the janitor had instructed. From here, she could see all the exits and most of the chamber.
Min-ji sat next to her. "You okay? You've been super tense all day."
"Just nervous," Sera lied. "First real dungeon and all."
"Yeah, I get it. But look—we're in the safe zone now. Nothing can go wrong here."
*Famous last words*, Sera thought but didn't say.
The instructors began their lecture on navigation techniques. Students pulled out notebooks. The atmosphere relaxed. This was just another classroom lesson, except in a dungeon instead of the academy.
1:47 PM. Forty-three minutes until the breach.
Sera's leg bounced anxiously. She forced herself to breathe steadily, to appear normal, to not alert anyone to her growing dread.
Where was the janitor? He'd said he'd be monitoring. Would he be in the dungeon? Outside? How would he even get in without being detected?
2:18 PM. Twelve minutes.
One of the monitoring devices started beeping. Jung walked over to check it, frowning. "Huh. Small mana spike. Probably just normal fluctuation."
"Should we report it?" Cho asked.
"Nah. It's within acceptable parameters. These sensors are oversensitive anyway."
Sera's hands clenched into fists. *Not normal. Not acceptable. Pay attention!*
2:27 PM. Three minutes.
The air pressure changed. Subtle, but Sera felt it—like the moment before a thunderstorm when everything goes still.
Several students looked up, sensing something wrong but unable to identify what.
The bioluminescent fungi started dimming.
"Instructor?" a student called out. "Why is it getting darker?"
Jung checked her equipment. "I... don't know. The monitoring devices show everything is—"
**CRACK.**
Reality split open.
Not gradually. Not with warning. One moment, the far wall of the chamber was solid stone. The next moment, it wasn't.
A tear in space itself, bleeding purple-black energy that made Sera's eyes hurt to look at directly. The air filled with a smell like burning metal and rotting meat.
And something stepped through.
It was vaguely humanoid—seven feet tall, skin the color of bruised flesh, muscles that moved wrong under the surface. Eyes that glowed red, too many teeth in a mouth that opened too wide, claws that looked like they could tear through steel.
**[WARNING: DEMON DETECTED]**
**[Entity: Malgrin the Corruptor - Demon Lord Rank 72]**
**[Threat Level: B-Rank (Peak)]**
**[Corruption Aura: Active]**
**[Mental Attack: Active]**
**[SURVIVAL PROBABILITY FOR F-RANK STUDENTS: 2%]**
The chamber exploded into chaos.
Students screamed. Some froze. Others ran toward exits that suddenly sealed themselves with barriers of purple energy.
The demon's mouth opened, and reality bent around its voice: "**ANOMALY DETECTED. TARGET: SERA. SECONDARY OBJECTIVE: ELIMINATE ALL WITNESSES.**"
It knew her name.
The janitor had been right about everything.
Instructor Jung moved first, her training overriding her shock. "CLASS F, FALL BACK! CHO, EMERGENCY BEACON, NOW!"
Cho fumbled for the emergency device on his belt. The demon flicked one claw lazily. Space compressed. Cho's upper body simply... ceased to exist. His legs stood for one horrible moment before collapsing.
Dead. Just like that. An experienced C-Rank instructor, killed before he could even activate the emergency beacon.
Jung's face went white, but she didn't freeze. "RUN! ANYONE WHO CAN MOVE, RUN FOR THE NORTH PASSAGE!"
But the north passage was sealed. So was the east. And the west.
Only one exit remained open—the one the demon was deliberately leaving accessible. The one that led deeper into the dungeon, away from the surface.
A trap. It wanted them to run that way.
Sera's mind kicked into gear, training overriding terror. *The reinforced chamber. The janitor's map. One entrance. Defensible position.*
That remaining open exit led in the right direction. It was a trap, but it was also their only chance.
"MIN-JI!" Sera grabbed her friend's arm. "Listen to me! We need to move NOW. Follow me exactly. Don't question, just run!"
"But the instructor said—"
"The instructor's plan won't work! Trust me!"
The demon moved. Not walked—moved, space bending around it as it closed the distance to the nearest student in an instant. Its claw swept out.
Sera didn't see what happened. Just heard the scream cut short.
"NOW!" She pulled Min-ji toward the open exit, her other hand grabbing two more students—a boy named Jin-woo and a girl whose name she couldn't remember.
Behind them, Instructor Jung tried to engage the demon, her mana flaring as she activated her abilities. She was C-Rank. Experienced. Trained.
She lasted eight seconds.
The demon's corruption aura hit her mid-attack. Her eyes went black. She turned toward the students—her students—and her expression twisted into something hungry.
"RUN!" Sera screamed to anyone still alive. "FOLLOW ME OR DIE!"
She ran.
Through the open exit, into the darkness beyond, dragging Min-ji and the others. Behind them, more screams. The sound of reality tearing. The demon's voice, speaking in a language that hurt to hear.
And footsteps. Multiple sets. Some students had followed.
Sera didn't slow down to count. The map was burned into her memory. Left at the fork. Straight for thirty meters. Right at the crystal formation. Down the narrow passage.
"WHERE ARE WE GOING?!" Jin-woo shouted.
"SOMEWHERE SAFER THAN BACK THERE!"
The passage narrowed further. She could see it ahead—the reinforced chamber the janitor had marked. Steel door, still intact, leading to a room with stone walls twice as thick as normal dungeon construction.
"INSIDE! NOW!"
She shoved students through the door. One, two, three, four—Min-ji stumbled through—five, six, seven—
The demon appeared at the far end of the passage.
Not running. Walking. Taking its time. It knew they were trapped now.
"**ANOMALY. COME OUT. MAKE THIS EASIER.**"
Eight students. Only eight had followed her. Out of fifteen Class F students and two instructors, only eight had made it this far.
Sera slammed the steel door shut and threw the heavy bolt. It wouldn't hold long against a B-Rank demon, but it might buy them time.
"What the hell was that thing?!" someone sobbed.
"Doesn't matter," Sera said, forcing calm into her voice. "What matters is surviving until help arrives."
"Help? Did you see what it did to Instructor Jung?! We're all going to die!"
"NOT IF I CAN HELP IT!" Sera snapped. Her hand moved to her hidden pocket, pulling out the modified emergency beacon the janitor had given her.
She pressed the activation button.
Nothing happened.
She pressed again. Still nothing.
*No, no, no—*
"The corruption field," Min-ji said quietly, her hands shaking. "That demon thing—it's blocking signals. We're cut off."
The steel door shuddered. Once. Twice.
The demon was testing it.
"**ANOMALY. YOUR TEACHER CANNOT SAVE YOU HERE. SURRENDER AND I MAKE DEATHS QUICK.**"
Sera's mind raced. The beacon didn't work. They were trapped. Eight F-Rank students and one partially-trained D-Rank against a B-Rank Demon Lord.
*Where is he?* she thought desperately. *He said he'd be here. He said he'd intervene.*
The door shuddered again, harder. Cracks formed in the metal.
It wouldn't hold much longer.
Sera drew her combat sword, the weight familiar and comforting in her hands. Around her, the other seven students drew their weapons, though most held them like they'd never been in real combat.
Because they hadn't.
"Listen," Sera said, her voice steady despite the terror clawing at her insides. "When that door breaks—and it will break—we don't try to fight that thing. We try to survive. We keep it busy. We hold out as long as we can. Maybe help will come. Maybe it won't. But we don't give up. Understood?"
Terrified nods.
The door shuddered a third time. The bolt snapped. The door flew open.
The demon stood in the doorway, too large to fit comfortably, having to crouch slightly. Its eyes fixed on Sera with something that might have been curiosity.
"**ANOMALY. YOU RESIST. GOOD. MASTER WILL BE PLEASED TO DISSECT INTERESTING SPECIMEN.**"
Sera raised her sword, every lesson from the janitor flooding through her mind. Stance. Breathing. Fear is useful only when controlled.
"Come on then," she said quietly. "Let's see if a 'specimen' can make you bleed."
The demon smiled—actually smiled—and stepped into the chamber.
And somewhere in the dungeon's shadows, a janitor moved through the darkness like a ghost, racing toward the screams, his sealed power beginning to crack as twenty years of experience prepared to face a demon lord with one hand tied behind his back.
The real battle was about to begin.