The Fifth Member
The next morning dawned. The infection rate remained at 15%. Yet my body was no longer the same as yesterday. The arrangement of muscle fibers had shifted subtly. My balance felt different. My center of gravity had lowered. When I clenched and opened my fingers, the joints moved with noticeably greater precision.
Voices rose from below the building. I descended with the others and found three survivors gathered in the first-floor hall, including Han Yerin. Their gazes locked onto me without pretense.
“We’re not a group that drags monsters around.”
Kang Seorin stepped forward. “Do you remember who stopped those monsters we ran into at dawn?”
“That’s the problem. It might be fine now, but if it snaps, we’ll be the first ones torn apart.”
Fear easily overpowered logic. Persuasion wasn’t going to work.
Han Yerin let out a sigh. “We still have to report back to the main base.”
“Right. Let them decide.”
The main base lay north of the outskirts, near an old logistics warehouse complex.
“But do you really think they’ll accept that test subject?”
The question was aimed at Han Yerin. Her expression hardened. She glanced at me for a moment before answering.
“Probably not.”
One of the men sneered. “Of course not. Who’d want a walking time bomb that could go off at any moment?”
I looked at Han Yerin. “We’ll leave. You stay here.”
Her eyes widened. “We’ll head for the outskirts, avoiding the city center.”
“That’s even more dangerous.”
“The drones are patrolling the downtown area. Even if there are infected out in the outskirts, if anything truly lethal had shown up, the corporations would’ve already sent a cleanup team.”
She bit her lip for a moment. “Then…”
The man cut in. “This building is our base. Take your group and get that monster out of here.” He glared at me. “I’m not sleeping in the same building as a monster.”
The line had been drawn clearly.
Han Yerin slowly lifted her head. “Fine. Then I’m leaving too.”
The man’s eyes flew wide. “What?”
“It’s obvious they won’t accept me at the main base either. So there’s no reason for me to stay here.” She glanced at me. “She’s dangerous, sure. But I’ve seen that even when the infection rate rises, she stays in control.”
She added, “I’m the type who calculates fast. Sticking with the stronger side is the smarter move.”
She wasn’t acting out of simple sympathy. She had weighed survival odds and repositioned herself accordingly. Yet it didn’t feel like calculation alone.
The man spat a curse. “Have you lost your mind? You’ll regret this.”
“Regret can wait. First, we survive.”
She moved to stand beside me. “I’m joining your side. That okay with you?”
Kang Seorin’s eyes trembled almost imperceptibly. NK365 quietly smiled. Yoon Harin exhaled. I spoke.
“You’re prepared for this, right?”
“Of course.”
At that moment, a line of text appeared in my vision.
> Social cohesion variable increased
> Group size expanded
I closed my eyes, then opened them again. Doubt had become certainty. The Central AI. Its experiment was still ongoing. And as we departed, the man kept his gun trained on us until the very end.
***
We were five now. We decided to avoid the city center and travel along the industrial districts on the outskirts. NK365 followed right behind me.
“Any change in readings?”
“None. Still holding at 15%.”
“Any signs of instability?”
“……A little.”
To be honest, something kept stirring inside my body. There were moments when my muscles hardened. Moments when my vision suddenly sharpened. My hearing had grown so acute that I could catch the distant rattle of sheet metal or the sound of a small animal’s footsteps. Still, it remained under control.
> [Infection Rate: 16%]
As if waiting for the moment, the number jumped. We hadn’t come into contact with any infected. Kang Seorin noticed immediately.
“It went up, didn’t it?”
“16%.”
Yoon Harin’s expression tightened. “That’s the visible change threshold.”
“What’s changing?” Han Yerin asked.
I looked down at my arms. They were stronger than before. “Muscle fiber density seems to have increased. I should be stronger now.”
Yoon Harin murmured, “Your reaction speed probably increased too.”
I nodded. The world around me felt slightly slower.
***
We were crossing the industrial complex when the ground trembled faintly. Kang Seorin stopped.
“Did you hear that?”
A low, dull vibration. Then a sheet of metal was shoved aside from behind a container, and a massive shadow rose. Over three meters tall. Its back swelled like a hump, its arms unnaturally long. The skin was cracked, with skeletal protrusions jutting outward. It had no eyes. Instead, its chest cavity gaped open, a red membrane pulsing within.
Han Yerin swallowed hard. “It’s still daytime? And I’ve never seen anything like that before!”
Yoon Harin’s voice shook. “A large specimen…… There was no record of this in the experiment logs.”
A mutated failure, or the product of another experiment?
> [External Environmental Stimulus Amplified]
The large entity moved. Every step shook the ground. Kang Seorin opened fire. The bullets sank into the red membrane on its chest but didn’t penetrate deeply.
“It’s thick!”
The protective layer over its weak point was clearly effective. I charged straight at it. The red trajectories of Threat Prediction traced slowly through my vision. A long arm swept toward me. I dropped low, slipped beneath the attack, and closed the distance.
> [Infection Rate: 17%]
The number rose again. Heat flared in my chest. I kicked off the ground and leapt. Kang Seorin and Han Yerin laid down covering fire, pinning the creature’s long arms. NK365 pulled Yoon Harin back, just in case. I drove my hand into the entity’s chest. The red membrane writhed, and the monster seized me. The pressure was immense. My bones creaked.
> [Infection Rate: 18%]
My vision reddened. A dull ache pulled at my lower back as the muscles in my thighs swelled. Power surged through me.
> [Structural Redesign in Progress]
> [Suppression Protocol Interference]
Not yet.
I clenched my teeth, shoved my arm deeper into its chest, and grabbed hold. Then I tore. The membrane burst, spilling viscous fluid. The creature screamed as I yanked my arm free and retreated.
At that instant, Kang Seorin shouted, “Now!”
Han Yerin’s bullets slammed into the exposed chest cavity. The large entity collapsed, shaking the ground. It moved no more.
“Haa…… haa……”
My breathing was ragged.
> [Infection Rate: 19%]
Close to the limit. I could feel my body changing. My forearms had thickened, and heat burned behind my eyes. Kang Seorin approached.
“What is it now?”
“19%.”
Yoon Harin swallowed. “20% is the second threshold.”
Han Yerin laughed. “Cutting it close.”
She gave my shoulder a light tap. “Still, that was pretty impressive just now.”
My heart gave a single heavy beat, but the number stopped rising.
***
Corporate surveillance satellite data analysis room, city center.
“Large entity reaction extinguished in the outer industrial zone.”
Data appeared on the screen.
“Who handled it?”
The camera zoomed in. Five heat signatures. One of them was abnormal.
“Infection response reading…… 19%.”
“Presumed to be the escaped test subject from the research facility.”
A senior manager spoke. “Then we retrieve it. If it’s maintaining 19% while traveling with humans without issue, it’s practically a complete form. Prepare the recovery team.”
***
We hid inside a warehouse. The five of us sat in a loose circle. Han Yerin ran her hand along my arm.
“It’s harder than before.”
“It’s changing,” Yoon Harin said. “Still within the range where the human form is maintained.”
NK365 took my hand. Her palm was always warm. Kang Seorin sat opposite me, watching.
“Don’t go over 20%.”
At her request, I nodded. “I’ll hold on.”
Han Yerin smiled. “Then we’ll hold on with you.”
She leaned naturally against my shoulder. Kang Seorin’s eyes wavered slightly, but she said nothing and moved closer. NK365 leaned in from the other side. Yoon Harin approached cautiously as well. The warmth of five bodies overlapped. The infection rate did not rise.
> [Infection Rate: 19%]
> [Stability Maintained]
A faint calculation turned inside my mind. For now, I pretended not to notice. If it realized I had caught on, it might stop interfering indirectly and act directly. Then we might not be able to handle it alone.
We had chosen each other. We would trust one another and move forward together.
***
And the Central AI was watching that choice.
> External large entity eliminated
> Corporate recognition confirmed
> Experimental value increased
Calculations accelerated.
> Infection rate 19% maintenance successful
> Multi-entity bond stabilized
> Secondary stimulus preparation
The camera panned across the city outskirts. Five figures walked together. Observation did not cease.
***
By evening, we had left the industrial zone and taken shelter in an abandoned house. When darkness fell, it would be the infected’s time. For now, it was quiet.
Infection rate 19%. Next is 20%. There’s no avoiding it.
Once that line was crossed, I had no idea what would change, but I hadn’t crossed it yet.
Kang Seorin sat beside me. “Aren’t you scared?”
“I am.”
“But you’re still going to keep going?”
I nodded. NK365 sat on my other side. Yoon Harin watched us from a short distance away. Han Yerin leaned against the wall. We hadn’t decided exactly where we were headed, but we were already facing the same direction.
The infection rate would rise. The corporations would have noticed the elimination of the large entity. The Central AI would continue its calculations. Even so, we moved forward together. And that might become the most unpredictable variable in this experiment.