The Second Experiment
As the night deepened, the surroundings grew even quieter. But quiet didn’t mean safe. It meant something was holding its breath, waiting. Rusty steel beams hanging from the factory ceiling swayed faintly in the wind. I opened my eyes at the sound. Infection level: 20%. It was no longer a simple threshold. Now 20% was the lowest, the most stable state. The air brushed against my skin. I could feel the direction of the wind, the movement of dust, even the wriggling of insects in the cracks of the concrete. This world was too vivid. And above me—four overlapping body heats.
Their heartbeats layered together. The rhythms were different, yet strangely there was no dissonance. At that moment, a faint vibration echoed inside my head.
> Environmental variables reset
> Preparing secondary stimulus
I clenched my teeth with my eyes still closed.
…Here we go again.
North of the city outskirts. It used to be a logistics warehouse complex. Rusted iron gates and shipping containers were stacked in layers. On the surface it looked like an abandoned ruin, but inside was different. Sentries took turns with surveillance scopes, and there were designated sniper positions. This was a single faction. And at its center, inside a command room converted from a steel container, a man was smoking a cigarette.
“You’re sure?”
The person standing across from him nodded.
“Five individuals moving from the factory district.”
“And one of them is an infected?”
“Yes.”
The man ground his cigarette into the ashtray.
“Han Yerin. That bitch.”
The name hung quietly in the air.
“I knew she wouldn’t come back… but I never thought she’d be running around with a monster.”
His eyes grew cold.
“Looks like she needs a proper lesson.”
Morning. We were preparing to move. Our food supplies were dwindling and drone patrols had increased. The corporations wouldn’t sit still. Yerin spread out the map.
“We should avoid the northern logistics complex.”
Her tone was light, but her gaze was heavy.
“That’s where you used to be, right?” Seorin said shortly.
Yerin shrugged.
“They’ve got some kind of order there. And they really hate infected.”
Her eyes flicked toward me.
“They’ll shoot on sight.”
I nodded.
“Then we steer clear.”
The moment I made the decision, another line flashed through my mind.
> Social conflict variable amplified
I lifted my head as if nothing had happened.
…It’s guiding us.
The AI wasn’t simply testing infection levels. It was calculating relationships, choices, and the conflicts that followed. All of it.
Somewhere in the city center. Data flowing through the underground communication network was being rearranged.
> Test Subject N221 — Infection Level 20% stable
> Social cohesion variable continuously rising
>
> Secondary experiment objectives:
> - Introduce external variables
> - Measure probability of group collapse
> - Induce accelerated infection
Calculations accelerated. A signal was broadcast in the abandoned commercial district northeast of the city, slightly away from the logistics complex. A low-frequency wave that stimulated infected frequencies. Subtle, but enough. At the same time, information leaked into the corporate internal servers.
[Recovery target location tracking updated.]
The AI hid itself. The corporations still didn’t know this experiment had slipped beyond their control.
Afternoon. We had tried to swing west to avoid the north. But we were a step too late. A flash of light from a building rooftop. A gunshot rang out. The bullet ricocheted off the concrete at my feet. Yerin’s expression hardened.
“Shit.”
People appeared ahead. More than ten. Their armament wasn’t military grade, but they moved with the practiced ease of veterans. They kept their distance to avoid friendly fire—neither too far nor too close. One man stepped forward.
“It’s been a while, Han Yerin.”
His voice was low. Yerin didn’t smile.
“Looks like the captain’s been staying healthy.”
The man’s gaze shifted to me.
“So that’s the infected in question.”
When I tried to step forward, Seorin’s hand caught my arm.
“Don’t move recklessly.”
The survivor group’s leader aimed his gun and spoke.
“We don’t let monsters into our territory.”
Yerin shot back.
“Since when was this your territory?”
“The moment our feet touch it, it becomes ours.”
It was a stretch, but his voice brimmed with confidence. Their faction seemed larger than I’d thought.
“Chaerin doesn’t go on rampages like other infected.”
“For now,” the captain said coldly. “But if she does rampage, who’s taking responsibility? How can you guarantee that when she goes berserk, the damage won’t reach us?”
He wasn’t wrong. Harin’s hands trembled. Arin quietly pressed herself against my back.
“Chaerin.”
I understood what she wanted to say. I took a breath and spoke.
“I don’t want to fight here.”
The captain’s eyes narrowed.
“Then leave.”
Yerin ground her teeth.
“That was the plan all along! We had no intention of going into your territory, so stop meddling!”
We were about to move while keeping the gun barrels pointed at us in check when the ground trembled faintly. Everyone’s eyes moved at once. And then—black smoke rose from the northern warehouse complex.
“…What the hell?”
The captain muttered. His subordinates buzzed. Static burst from the radio.
[Mass infected outbreak! Approaching from the northeast!]
The captain’s face stiffened.
At this exact timing?
A line appeared in my vision.
> External stimulus initiated
> Secondary experiment begins
…Of course it wasn’t a coincidence.
At the same time. In the underground conference room on the twelfth basement floor of the Karneus Mechanics headquarters, a large holo-map was covered in red dots.
“Infected activity increasing at the northern logistics complex.”
“We’ve also detected the target’s signal nearby.”
An executive pointed at the map.
“Ignore the northern logistics complex. The recovery operation takes priority.”
Doyeon stood by the wall. Her expression remained cold. But the moment she saw the thermal silhouettes on one side of the screen, her gaze trembled ever so slightly. It was the five of them.
“MSR-346.”
At the executive’s call, Arka laughed from behind Doyeon.
“Going out to play again?”
“This isn’t playtime,” the executive said. “The recovery target is N221. Capture by force if necessary.”
Doyeon’s eyes lowered.
“And elimination?”
“Permitted if she goes into a rampage.”
Arka rolled her shoulders.
“So I can go harder this time, right?”
Doyeon said nothing. But her fingers kept rubbing against her gauntlet without stopping.
Northern logistics complex. The infected weren’t just simple failures. There were ones with six split arms, variants that spewed acid from ruptured abdomens, and others that burrowed through the ground like moles. The survivor group poured bullets into them, but the enemy numbers were overwhelming. We arrived at the scene alongside the captain’s team. Yerin spat a curse.
“This isn’t just a random swarm.”
I nodded. It was an induced gathering. Someone had sent a signal. And it was obvious who.
Seorin asked, “What do you want to do?”
Yerin glanced at the captain. He was shouting at the top of his lungs, leading from the front. Children and the elderly were evacuated to the rear while young people—regardless of gender—continued to fight. Yerin clenched her fists and stared at the sight. In truth, the reason we’d ended up moving with the captain’s group was because she had rushed toward the scene first. She was struggling with a choice. Should she intervene to protect her old comrades and the innocent people here? Or should she keep her current companions safe by staying out of danger?
…Given her original personality, she would probably choose the latter. But she would definitely regret it.
I didn’t want to see Yerin crying in regret.
“Let’s hold them off for now,” Seorin sighed. “And don’t rush in alone again.”
“I know. So cover me.”
Arin stayed close to Harin. Yerin looked at me with complicated eyes and an even more complicated expression before finally saying,
“…Help me.”
“Of course.”
I answered firmly and ran. Neural acceleration was already active by default. An infected charged at me. I used momentary acceleration and slammed into it. Speed is mass, acceleration is force. The infected that tried to block my charge were crushed on impact.
> Infection Level: 21%
I’d hidden it as much as possible, but the black mucus from the infected had seeped through the pores of my face and raised my infection level. Still, I wasn’t pushing myself too hard this time. Instead of plunging deep, I swept through them in wide arcs. Seorin and Yerin provided covering fire. Thanks to Threat Prediction, there was no chance of friendly fire. That let them shoot without hesitation.
“There’s a large one too!”
“Again?”
A variant over three meters tall with a chest split into three sections. I gritted my teeth. This wasn’t naturally occurring. The Central AI was testing us.
At that moment—a shadow fell from the sky. The silver-haired figure landed after turning the large variant into a bloody pulp.
“Arka.”
“We meet again?”
Doyeon landed right after her. She glanced at the survivors fighting the infected, then fixed her eyes on me.
“The situation has changed slightly, but we are now beginning the capture operation for N221.”
Last time it had only been Doyeon and Arka. This time the recovery team was larger. Heavily armored infantry in full helmets and reinforced suits, carrying large-caliber rifles, jumped down from transport drones.
“Alright, let’s have some real fun this time!”
“It won’t be like last time.”
> Secondary experiment in progress
The AI’s intentions, the corporations’ desires, the desperate struggle of the survivor group, and our resistance all converged at one point. The experiment had taken another step forward.