I Built a Safe Zone in the Dead World

Rain crashed endlessly across the ruined city while thunder shook the burning skyline above. Flooded streets reflected orange firelight from destroyed military vehicles while smoke drifted through shattered buildings. Gunfire echoed across the battlefield while Black Flag and Eden forces clashed violently around the giant underground platform.

But none of it mattered anymore, Because everyone had frozen, At the edge of the massive underground entrance— A figure slowly emerged from the darkness below.

Human-shaped, Barefoot, Wearing torn hospital clothing stained with blood and black markings.

Long black hair fell across his face while glowing silver eyes illuminated faintly through the rainstorm. Dark synchronization markings covered nearly every inch of his skin like living veins while black energy moved around him unnaturally.

And despite everything terrifying about him—

His smile looked warm, Human.

"...You grew up, little brother."

Silence consumed the battlefield instantly, Arata stood completely frozen.

His heartbeat pounded violently inside his chest while memories shattered through his mind endlessly, A child laughing beside him.

Training together inside laboratory hallways.

Holding hands through glass containment walls, Promises, Screams, Blood, Then darkness.

"...Riku..."

The name escaped Arata’s mouth automatically, The figure smiled softly afterward.

"...You remembered."

Akari immediately looked between them in shock. "...That’s really your brother?"

No one answered.

Because honestly— Everyone else was trying to understand too.

Yuna slowly pointed toward Riku afterward. "...Why is the strongest thing in the story wearing hospital clothes?"

Reina smirked faintly despite the tension. "Honestly it makes him scarier."

Meanwhile Ren’s gray eyes remained fixed entirely on Riku now.

For the first time since appearing— Ren looked genuinely cautious.

"...Alpha."

Riku’s glowing eyes slowly shifted toward him afterward. Then calmly— He smiled again.

"...Eden still exists."

The way he said it felt strange, Like disappointment mixed with exhaustion.

Tyrant-01 immediately knelt before Riku afterward, The giant armored monster lowered its massive head completely without hesitation.

"...Primary host confirmed."

Everyone froze again. Because the creature that nearly destroyed the battlefield— Was obeying him like a servant.

Lucien’s expression had completely darkened now.

"...Impossible."

Riku slowly looked toward him afterward.

And instantly— The atmosphere changed.

The warmth vanished from his face completely, Only cold hatred remained.

"...Lucien."

Black energy exploded outward from Riku violently.

Booooooooom!!

The entire underground platform cracked instantly while shockwaves shattered nearby windows across the ruined city. Military soldiers were thrown backward while Black Flag operatives collapsed under the pressure alone.

Even Arata struggled standing.

Because unlike normal synchronization— Riku’s presence felt overwhelming. Like evolution itself had taken human form.

The system exploded before Arata’s vision immediately.

[PRIMARY HOST DETECTED]

[Synchronization Response: Submission Instinct Activated]

[Warning: System Authority Overridden]

Arata’s eyes widened instantly, Submission instinct? The darkness inside him reacted automatically toward Riku, Not fear, Recognition.

Like the system itself acknowledged Riku as something superior, Akari immediately grabbed Arata’s arm again afterward.

The warmth from her touch stabilized him slightly, And unexpectedly— Riku noticed.

His glowing eyes shifted toward their joined hands, Silence followed briefly, Then softly—

He smiled again.

"...So that’s how you survived."

Akari frowned slightly. "...What does that mean?"

Riku calmly walked farther onto the battlefield afterward while rain poured across his body. His movements looked strangely normal.

Not monstrous, Not robotic, Just human.

Which honestly made him even scarier.

"Synchronization destroys emotions first," Riku quietly explained afterward while looking toward Arata. "Isolation accelerates the corruption." His eyes shifted toward Akari again briefly. "But emotional attachment slows the process."

Ren immediately narrowed his eyes. "...You knew that?"

Riku gave a small tired smile.

"I was the first test subject." Silence followed briefly afterward. "I learned everything the painful way."

Arata’s chest tightened painfully hearing that.

Because suddenly— The monster standing before him no longer looked like a monster.

He looked like someone who suffered alone for years. Lucien suddenly stepped forward afterward while black energy gathered violently around him.

"You should’ve stayed sealed underground."

Riku’s expression immediately became emotionless again.

"...You killed them."

The battlefield grew silent once more.

Rain fell heavily around the ruined city while thunder echoed overhead.

Lucien calmly answered:

"Necessary sacrifice."

Riku disappeared instantly afterward, Too fast.

BOOOOOOOOOOM!!

Lucien barely blocked the punch before being launched violently through multiple destroyed buildings. Shockwaves exploded across the battlefield while the underground platform cracked apart further.

Everyone froze, Because Riku moved even faster than Ren. Faster than Tyrant-01. Possibly faster than Arata himself.

Lucien emerged from collapsed debris moments later while blood dripped faintly from his mouth now. And for the first time— He looked pressured. Actually pressured.

Riku slowly walked toward him afterward while black energy twisted around his body like living shadows.

"You experimented on children."

Lucien quietly wiped blood away afterward.

"And humanity survived because of it."

Riku’s glowing eyes darkened instantly.

"No." Silence followed briefly. "...Humanity died because of it."

Then he attacked again. The battlefield exploded.

Black energy collisions tore through surrounding buildings while shockwaves blasted apart military barricades. Lucien retaliated using sharp energy constructs while Riku casually destroyed them barehanded.

Neither looked human anymore.

Yuna stared blankly from behind destroyed concrete. "...I officially miss normal zombies."

Kaede calmly fired arrows toward approaching Black Flag forces beside her. "...Power escalation became severe."

"That sounds like a game update."

Meanwhile Arata couldn’t stop staring at Riku.

Because every movement triggered more memories.

Riku smiling while protecting him from bullies inside the laboratory compound.

Riku volunteering for synchronization experiments first.

Riku screaming while black markings spread across his body.

And their father crying helplessly outside the containment chamber.Arata slowly realized the horrifying truth afterward.

Riku wasn’t born a monster, Humanity made him one. Akari quietly noticed his expression changing again.

Then softly asked, "...What are you thinking?"

Silence.

Rainwater dripped from Arata’s hair while explosions illuminated the battlefield around them, Then quietly— He answered.

"...He suffered alone because of us."

Akari’s eyes softened immediately, Because honestly— That sounded exactly like Arata himself. Always carrying pain alone. Always sacrificing himself first.

The similarities between both brothers suddenly became terrifyingly obvious.

Meanwhile Riku finally stopped attacking Lucien afterward. Not because Lucien won.

Because Riku lost interest. The glowing-eyed man slowly turned back toward Arata instead.

Then quietly— He smiled.

"...Come with me."

Silence spread instantly, Akari immediately stepped closer toward Arata protectively.

"No."

Riku looked toward her calmly afterward.

"I’m not trying to hurt him."

"That doesn’t matter."

Riku remained silent briefly, Then softly asked:

"...Do you know what happens after synchronization reaches one hundred percent?"

Akari froze slightly, Because honestly—

Nobody had explained that yet.

Riku’s glowing eyes shifted back toward Arata afterward.

"You disappear."

The system flickered violently before Arata immediately.

[Synchronization Rate: 80%]

Riku continued quietly:

"The system reconstructs your mind completely." His expression darkened slightly. "Memories remain. Personality doesn’t."

Rain continued falling softly around them.

Then Riku added:

"That’s what happened to me."

Silence consumed the battlefield afterward.

Even Ren looked away briefly, Because suddenly— Everything made horrifying sense. Riku wasn’t emotionless naturally.

The synchronization had slowly erased him over years underground. Only fragments of the original brother remained.

And somehow— Akari was preventing Arata from suffering the same fate.

Lucien suddenly laughed softly afterward despite the tension.

"...Yet another reason emotional attachment creates weakness."

Riku’s expression instantly darkened.

"...You still understand nothing."

Booooooom!!

Lucien was launched across the battlefield again before anyone even saw Riku move.

This time the impact destroyed an entire tower.

Yuna slowly blinked afterward. "...Okay he definitely has anger issues."

Reina grinned dangerously. "I like him."

"That also concerns me emotionally."

Meanwhile Eden operatives suddenly activated emergency alarms across the underground platform. The white-haired operative shouted afterward:

"More containment sectors breached!"

Ren’s expression hardened immediately.

Then suddenly— Screams echoed from below the city again, Not one scream.

Hundreds. Something was happening underground, Something catastrophic.

Riku immediately turned toward the darkness below afterward. And for the first time— Fear briefly appeared in his eyes.

"...No."

Everyone froze instantly. Because if Alpha feared something— Then what else existed underground? The ground shook violently afterward.

Boooooomm!!

Massive cracks spread across portions of the underground platform while mechanical structures collapsed beneath the city.

Then— Something enormous moved below them, Far larger than Tyrant-01, Far larger than Alpha.

Even the rainwater around the platform trembled from the movement alone. The system exploded violently before Arata’s eyes.

[WARNING]

[UNKNOWN ENTITY APPROACHING]

[Threat Level: Unmeasurable]

[Emergency Protocol Activated]

Everyone stared toward the darkness beneath the underground city afterward.

Then slowly— A deep distorted voice echoed upward, Not inside minds, Not through speakers, Real sound, Ancient, Inhuman.

"...Synchronization... incomplete..."

Cold fear spread across the battlefield instantly. Riku’s expression completely changed.

"...It awakened."

Ren immediately activated combat weapons around him afterward.

"Eliminate surface access immediately!"

But before anyone moved— Gigantic claws suddenly burst upward through the underground platform.

Craaaaaaaaaash!!

Metal exploded everywhere while massive black limbs tore through steel structures violently. Eden operatives were thrown screaming through the air while floodlights shattered instantly.

Then— Something began climbing upward from the darkness below, Not human, Not infected, Something else entirely, The first true monster of the apocalypse.