The concrete corridors above the sublevels were even worse than the ones below.
Not because of what they saw—but because of what they didn't.
No growls. No moaning. No warning. Just silence. The kind that wrapped around your throat and dared you to break it.
Yu Ren kept close behind Kai as they moved, one hand gripping a bent crowbar, the other resting near his pocketed utility knife. His mind was still half on the Observer-Class they'd narrowly avoided. He couldn't stop thinking about its faceless mask and the way it glided instead of walked, as if reality itself didn't fully accept it.
Even now, hours later, a low pressure sat on the back of his skull. Like he was still being watched.
Kai's movements were slower than usual—wounded, tired—but precise. Every few minutes, he paused and checked the hallway corners or scanned ceilings for broken vents and access shafts. The path they followed twisted into forgotten parts of the city's old transit system, long since buried and collapsed.
They hadn't spoken since they'd left the maintenance room.
Not until they stumbled across the map.
It was half-pinned, half-melted into the wall of what used to be a city operations center. A display board—cracked, blackened, but still showing fragments of its original layout. And on the far right, glowing faintly with system interface flickers, was a pulsing blue marker.
Yu Ren squinted. "What's that?"
Kai stepped forward, brushing away some ash and grime. The words were nearly illegible, but the marker was tagged with three blinking characters:
[H7-B]
Yu Ren tapped his interface, calling up his map. The building's local system connected, syncing data with his own UI. It took a moment, but the new information filled in.
A zone far northwest lit up in pale blue: Safehouse B, Site H7.
He turned to Kai. "Is that the signal you were tracking?"
Kai gave a short nod. "Looks like it. If this data is accurate, there might still be an operational shelter there. Possibly even power. Maybe survivors."
"Or corpses," Yu Ren muttered.
Kai didn't argue.
Yu Ren tilted his head. "How far?"
Kai scanned the map. "Two zones away. Through R-Line Transit tunnels. We'd need to cut through Sector G. Might be unstable."
Yu Ren winced. "How unstable?"
Kai pointed at a red icon flashing beside Sector G.
Biohazard Zone
Status: Active Mutation Field Detected
Threat Level: Moderate–Severe
Yu Ren groaned. "Why is it always the middle path that's filled with nightmares?"
"No time to go around," Kai said simply.
Yu Ren stared at the map a little longer, then sighed. "Fine. I vote we survive. Maybe even pick up a sandwich if any mutated convenience stores are still open."
Kai raised a brow. "Still thinking about food?"
"Always."
They pushed forward.
—---
The G-Zone tunnels were pitch black, save for flickering emergency lights powered by a decaying generator system. The walls were slick with moisture, the floors half-covered in fungus that pulsed faintly when disturbed.
Yu Ren hated the fungus.
Ever since he'd seen it blink.
Literally blink.
His crowbar tapped along the wall as they moved in a crouch, careful to avoid stepping on anything with too much color. The brighter it was, the more likely it would try to eat them.
"Kai," he whispered after a while. "What happens if that Observer-Class... finds us again?"
Kai's jaw tightened. "Then we run. If we're lucky."
"...And if we're not?"
Kai hesitated. "You won't have to worry about it long."
Yu Ren made a face. "Reassuring."
They pushed deeper into the tunnels, every step slow and deliberate. Yu Ren had just stepped over a collapsed steel beam when his system pinged again.
Perception Check Passed
Abnormal Movement Detected: Left Tunnel Fork
Enemy Type: [Unclassified]
Distance: 28 meters
Behavior: Stationary | Aggressive Aura Detected
Yu Ren stopped cold. "Kai."
"I see it."
In the dim, ahead of them, something pulsed. Not light—but movement. Like the twitch of muscle beneath stretched skin. A shape hovered just around the corner. Tall. Slightly hunched. Breathing.
Kai raised a hand and pulled Yu Ren back behind a pipe column.
Yu Ren leaned close. "What is that?"
"Looks like a spine-drinker," Kai murmured.
Yu Ren stared at him. "Please tell me that's slang for something."
Kai didn't answer.
Yu Ren peeked again. The creature was just barely visible—long-limbed, with backward-jointed knees and a neck that stretched with every breath, like a balloon being filled. Its chest split vertically every few seconds to exhale what looked like smoke.
"Maybe we should go around," Yu Ren whispered.
"No time," Kai replied. "It's blocking the main path."
"Then maybe we should go back."
Kai reached for his belt and pulled out a small spherical device. It pulsed blue.
Yu Ren stared at it. "What is that?"
"Pulse decoy. Noisy. Short range."
Yu Ren blinked. "Wait, are you going to throw that—"
Kai lobbed it down the opposite hall.
The moment it clattered against the metal wall, the creature screamed.
Not a normal scream.
It was wet. Gurgling. Filled with clicking jaws and tearing sinew.
Then it bolted—away from them, chasing the noise.
Yu Ren was already moving. "Go go go!"
They dashed down the cleared path, ducking past old crates and fallen cables, Yu Ren trying not to slip on the bioluminescent sludge that covered half the corridor.
Behind them, the scream echoed again—closer.
"It's faster than it looks!" Yu Ren yelled.
"No talking!" Kai shouted back.
They burst through the end of the tunnel and slammed into a decaying control room. The door creaked as Kai pulled it shut behind them, locking it with a sliding bar.
They both collapsed on the floor, panting.
Yu Ren wiped sweat off his face. "Let me guess... that wasn't your only decoy."
Kai shook his head. "Last one."
Yu Ren groaned. "I'm going to die covered in mold."
Trait Advancement
[Survivor's Instinct II] Unlocked
Effect: Movement speed increased during escape scenarios. Stamina drain slightly reduced.
Progress to Tier III: 3/6 successful evasions
Kai's Status Updated
[Bleeding Reduced]
System-assisted clotting in effect.
Warning: Infection risk remains.
Yu Ren read the updates and let out a shaky breath.
"Hey," he said softly, "we're almost to H7-B, right?"
Kai nodded. "Less than a kilometer."
Yu Ren leaned back against the wall. "Good. Because I'm one zombie away from giving up and letting fate take the wheel."
Kai chuckled.
It was the first time Yu Ren had heard him laugh—truly laugh. It was quiet, breathless, and short-lived, but it was real.
Yu Ren smiled, tired but genuine.
Whatever H7-B was, it had better be worth it.
---
To be continued.