The buzzing of flies was the first sound Yu Ren noticed.
It wasn't loud. In fact, the echoing silence in the ruined stairwell made every little sound stretch and twist unnaturally, as though the air itself held its breath. Dust filtered down in beams of weak sunlight above them, catching on torn wires and fragments of bone. Kai hadn't said a word since they escaped Sublevel B2.
Yu Ren glanced at him, trying not to wince at the smear of red darkening Kai's shirt. His bandages were soaked. His breath was shallow but even, and his eyes had the dull haze of someone clinging to consciousness through sheer force of will.
They had retreated to a small maintenance room behind a half-collapsed corridor—a concrete shell filled with rusted lockers, water-stained tiles, and the sharp metallic scent of blood. There, they could rest.
Kai sat slumped against the far wall, chest rising slowly. His expression remained unreadable. Yu Ren crouched beside him, unzipping the first aid pouch he'd pulled from a med box downstairs. His hands shook.
"Let me—" Yu Ren started, then paused. The words felt foreign. Too gentle, too intimate. He hated how afraid he was that Kai would reject them.
Kai didn't move. Didn't protest.
That alone made Yu Ren more nervous.
He removed the sodden bandage and saw the ragged cut beneath—clawed, almost torn, by one of the creatures that had emerged in the swarm. The blood had stopped, but infection would be another battle.
As Yu Ren worked in silence, the System interface blinked in the corner of his vision.
New Affection Update
Kai - +3 Affection Points
[Current Status: Guarded Trust | Tier: 2]
Shared proximity under stress triggers minor bond development. Continue exposure for increased results.
He ignored it. It felt wrong—like measuring the distance between their breaths with a ruler. Kai wasn't some simulation. He was real. Hurt. Distant. And yet still here.
"Are you gonna pass out?" Yu Ren muttered, hoping levity might help.
Kai let out the faintest huff of air, a sound that might've once been a chuckle. "Not yet."
"Good," Yu Ren replied. "Because if I get dragged off by some blood-dripping zombie dog while you're unconscious, I'm haunting you."
"That's fair."
The silence that followed wasn't awkward. It was heavy. Real.
Yu Ren leaned back, pressing his palm against his forehead, wiping away sweat and grime. Then he whispered, "Thanks. For coming back for me."
Kai didn't answer for a long time.
Finally, he said, voice low, "I couldn't leave you there."
Yu Ren blinked. "Because of the mission?"
Kai's expression was unreadable. "...Because it's you."
Yu Ren didn't respond. He couldn't. His chest felt too tight. He stood and turned away, pretending to dig through a locker.
Behind him, the System chimed again.
Trait Development Notice
Subject: Yu Ren
Psychological Threshold Surpassed
New Trait Unlocked: [Resilience I]
Description: Mental recovery time decreased. Panic resistance increased.
Progress: 1/5 to [Resilience II]
He stared at it, jaw tight. The System was watching everything. Every emotion. Every crack in his voice.
Was it trying to help—or shape him?
A faint scrape behind him made Yu Ren turn.
Kai was trying to stand.
Yu Ren rushed to his side. "What are you doing?!"
Kai leaned against the wall, eyes half-lidded but alert. "We can't stay long. Something's coming."
"How do you know?"
Kai's hand drifted to a battered device clipped to his belt. It looked like an old emergency radio—but with pulsing glyphs instead of dials.
"Signal disturbance," Kai said. "Same reading I saw before the swarm emerged."
Yu Ren swallowed hard. "So... not just a random horde."
Kai nodded.
Suddenly, a distant clang echoed down the stairwell.
Both of them froze.
Then Yu Ren heard it—a faint whisper. Not a voice, but a low, humming static that seemed to grow louder as it moved.
System Alert: New Entity Detected
Classification: Unknown | Observer-Class
Status: Passive Scanning Mode
[Warning: Direct eye contact may trigger engagement]
Yu Ren stared at the screen. "What the hell is an Observer-Class?"
Kai's face went pale. "Don't look at it."
Yu Ren stiffened. "What?"
Kai gritted his teeth. "They don't always attack. They record. Watch. Sometimes... if you stare too long, they see you seeing them. That's when you're marked."
Yu Ren's skin crawled.
The humming grew louder, closer.
They barely had time to slip out of the maintenance room and wedge themselves behind a ventilation shaft before something floated past the broken corridor.
It didn't walk.
It hovered.
Humanoid only in silhouette, the thing was a patchwork of cables, pulsating veins of red light, and a blank white mask—like a mannequin face without features. It scanned slowly from side to side. And Yu Ren felt a primal urge to run, to hide, to not be perceived.
Kai's grip tightened around Yu Ren's wrist.
Neither of them breathed.
The creature paused... then glided silently down the hallway and out of sight.
The System let out a soft ping.
[Observer-Class Presence: Exited Scan Range]
Safe Status: Tentative
Only then did Yu Ren dare to speak.
"What was that?"
Kai didn't answer immediately.
Finally, he said, "One of the reasons we lost."
Yu Ren turned to him slowly. "You've seen them before."
Kai gave a faint nod. "Not just me. My unit. Back then... before the world broke. They watched us. Recorded battle patterns. Locations. Weaknesses."
Yu Ren realized something.
"Your unit… you were part of a project. A test group. You're not just some survivor, are you?"
Kai looked at him.
But didn't deny it.
Yu Ren didn't push further. The silence that followed was filled with more meaning than answers would have.
He stepped away, looking at the corridor. "So what now?"
Kai's voice was hoarse but steady. "We keep moving. There's a broadcast signal I've been tracking. It's been growing stronger. A human frequency."
Yu Ren narrowed his eyes. "Another survivor?"
"Maybe. Maybe a trap." Kai looked up. "But it's the only direction left."
Yu Ren exhaled. He wanted to believe in people. But in this world, hope had teeth.
Still… he wasn't alone.
"Let's go, then," he said, shouldering the medkit and offering a hand.
Kai took it.
---
To be continued.