Chapter Text
“Damn it! How can they be so fucking stupid?!”
Ryu ‘Keria’ Minseok ripped the comms headset off his ears in a fit of rage. Without a second glance, he hurled it straight out the window of the armored SUV, which was tearing madly through the dead wasteland.
The howling desert wind roared into the cabin, bringing a flurry of dust and sand that completely ruined his already messy black hair. His narrow eyes flashed with pure fury. Still unsatisfied, Keria struck a heavy fist against the passenger door, making the entire chassis shudder violently.
“Hey, you crazy bastard, keep it under control. If you wreck this ride, I’m leaving you to walk back alone, you hear me?”
Moon ‘Oner’ Hyunjoon steered the wheel with one hand while his other rapidly swiped across a transparent virtual console, projecting the emergency alert they had just received onto the main screen. In stark contrast to the volatile volcano sitting right next to him, Oner appeared vastly more composed and grounded. His thick, form-fitting Sentinel Special Forces uniform threw the rippling muscles of his arms into sharp relief every time he maneuvered the vehicle.
The 3D display flashed, revealing the profile picture of a petite girl with short hair. Beside it were the basic lines of information that Keria had long memorized over the past few months. Only the very last line had been freshly updated in a glaring, eye-searing red.
[Deployment: Citadel No. 1 ➔ Citadel No. 4]
“What the hell are those idiots at the Tower even doing? Do they want the Sentinels in Citadel 1 to go completely insane before they’re satisfied?!” Keria snarled, feeling as though he were about to explode from sheer frustration. A Sentinel’s hyper-acute hearing was currently turning the engine’s roar into cracks of thunder right next to his ears. The smell of gasoline, the stinging dust, the blazing sunlight outside... everything was being magnified a hundredfold, clawing at his senses to an alarming degree. He needed a Guide. He needed a Cleanse the moment he set foot back in Citadel 1 to end this godforsaken mission. And yet, those old fossils at the Tower had just snatched away their last remaining Guide!
Insane. Those bastards had truly lost their minds. Did they want to bleed the Sentinels of Citadel 1 dry until they died? Fine. If he ended up succumbing to Feral and burying his bones in this desert, the biggest loss would fall upon that rotten Tower, not him.
After all, who told them he was their precious S-class Sentinel?
Oner glanced at his heavily panting comrade. Sighing, he waited until Keria’s mental tremors subsided a little before speaking in a low, heavy voice.
"Don't worry. They've already dispatched reinforcements to Citadel 1 as a replacement.” Knowing his friend's explosive temper, Oner quickly swiped the virtual screen away to keep it out of sight. Keria didn't reply. He merely let out a cold snort and leaned his head back against the headrest, his exhausted eyes tracking the endless, rolling sand dunes outside.
The mental overload caused fragmented memories of the past to abruptly flood his mind. Keria recalled the early days when he had first met Oner. Back then, this A-class Sentinel was an incredibly impulsive, arrogant, and bloodthirsty feral beast. He had never shrunk away from any of the Tower's insane training regimes, always completing them in the most ruthless manner possible. His massive, predatory physique stood as a testament to that era.
But now, looking at the man quietly holding the steering wheel beside him, Keria couldn't help but feel a wave of irony. Time truly possessed the power to grind down a person's sharp edges, or perhaps, “someone” had managed to tame the beast. Then again, the only reason Oner could afford to be so wild back then was because he had someone constantly backing him up, powerfully shielding his mental domain so he could charge forward. Now that even the Citadel's only Guide had been taken away, Oner had no choice but to suppress that side of his personality if he didn't want to lose his mind and die a pointless death. Eventually, this forced restraint grew to become a genuine part of him.
Though ranked one tier below Keria on the Tower’s Sentinel registry, Oner was absolutely not inferior in terms of physical prowess. In fact, he far surpassed him. What set Keria apart was his anomalous Mental Control capability. One shouldn't judge Keria based on how easily he lost his temper; his Mental World was exceptionally stable and resilient, allowing him to stand entirely alone on almost any mission. That was precisely why the higher-ups dared to let these two Sentinels roam outside the Citadel walls without an accompanying Guide. As for Oner? Whenever Keria saw him on the verge of succumbing to Feral, he would simply knock him unconscious and drag him back. Simple as that.
Yet, no matter how powerful a trump card Keria was, Citadel 1 could not sustain itself without Guides. Keria wasn't the only Sentinel stationed there. The others desperately needed Cleansing too.
Since when had their shortage of Guides become so dire that even a non-combatant Guide was being snatched away?
Keria bit his lip, rubbing his temples in a futile attempt to pacify the renewed wave of anger clouding his mind.
.
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The exponential leap of technology always came hand in hand with filthy, dark undercurrents. When human greed and industrial waste bled into nature, mutation began to take root. Originating from microscopic alterations invisible to the naked eye, they gradually evolved into grotesque, nauseating monstrosities.
Animals turned fiercely aggressive; marine life violently thrashed, tearing the oceans apart. The climate mutated into deadly extremes: if it wasn't a scorching heatwave blistering the skin, it was a sudden blizzard freezing all signs of life. Rising sea levels swallowed low-lying lands, while shifting tectonic plates fractured and dissolved the old continents.
Humanity grew increasingly frail in the face of novel, plague-like diseases. To survive, they were forced to cluster together, erecting colossal weather barriers to safeguard what little life they had left, marking the birth of the world's very first outposts.
Everything heralded an impending doom.
Doomsday - the day the entire planet was swallowed by darkness. The mutated creatures officially evolved into Monsters, slaughtering and purging the global population down to roughly a third of its original size. In the span of a single, agonizing year, seventeen of the most heavily fortified defensive outposts were completely wiped off the map.
The five remaining sectors, housing the sharpest minds and the strongest warriors, coalesced to form the Alliance of the Five Towers: LCK, LCP, LPL, LEC, and LCS. Each Tower governed a distinct territory, painstakingly carrying humanity through the raw fury of mother nature.
Humans came to remember that dark milestone as The Year of the Purge.
In the 10th year Post-Purge, scientists discovered the first child who possessed five senses heightened to a miraculous degree. The child was brought back to the Tower for research, unlocking the greatest turning point in human history: mankind finally possessed a weapon to fight back against the Monsters outside.
Those children gifted with such supernatural traits were called Sentinels.
Yet nature always demanded a cruel equilibrium. The price for their hyper-acute five senses was an incredibly volatile neurological state. Absorbing too much information from their surroundings left Sentinels highly susceptible to sensory overload. Once their Mental World collapsed entirely, they would fall into a state of Feral - losing all reason and humanity, turning violently feral, and ultimately mutating into monsters themselves.
To prevent such tragedies, scientists tried everything, from high-dose sedatives to specialized soundproof isolation chambers, but these were merely temporary fixes. That was until they discovered Guides, individuals possessing unique mental wavelengths capable of entering a Sentinel’s Mental World to soothe them and cleanse the environmental impurities left behind.
All Guides and Sentinels fell under the absolute jurisdiction of the Tower, destined from birth to serve as the shield of humanity. They were glorified by the Tower and immortalized for generations. Their families shared in the prestige, enjoying an elevated status in society.
Keria and Oner were under LCK Tower.
The old Eurasian continent was split into quadrants, with the LCK Tower governing the Northeast region extending toward the old North Pole. The central hub houses the Tower and serves as the residential zone for civilians, known as the Center. The vast majority of the territory outside the Center consists of uninhabitable dead zones. To combat this, the LCK constructed ten heavily fortified citadels, forming a closed defensive ring that completely shields the Center within.
In principle, Sentinels and Guides were always Bonded and distributed evenly across the ten citadels. Yet currently, this distribution had fallen into a bizarre state of chaos.
Or rather, it was only Citadel 1 that was abnormal. Because every single Sentinel stationed in Citadel 1 remained entirely Unpaired.
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.
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“Do you get the feeling that something bad is about to happen?”
Oner’s low voice cut through the air, dragging Keria out of his chaotic spiral of thoughts. He raised an eyebrow, casting a sidelong glance at his best friend’s expression after such a random, open-ended question. Ultimately, Keria just shrugged, feigning indifference. What did it matter whether he felt something strange or not? Could he actually change anything?
It had been six years since he officially became a Sentinel, and Keria had bitterly come to accept a cold reality: no matter how hard he struggled or how strong he grew, his life was nothing more than a puppet operated by the strings of the Tower. His destiny - whether it meant bleeding out on these scorching sands or being buried beneath the freezing snow out there - was predefined to end in a "glorious" death on the battlefield to save the world. And after that, the name Ryu 'Keria' Minseok would be solemnly engraved somewhere among thousands of others on the LCK Tower’s memorial wall.
Since the exact same ending awaited him sooner or later, Keria had long given up on pondering the meaning of this world or his life.
Watching his friend disconnect from reality once again, Oner let out a heavy sigh. He silently thought to himself that if Keria knew what had happened after he threw his headset out the window, he wouldn't be sitting there acting indifferent, he’d be screaming curses at the entire universe.
This guy's personality was truly something else.
BOOM!
The armored SUV suddenly bucked violently into the air before shaking uncontrollably. Keria instinctively grabbed the door handle to keep from being thrown across the cabin, while Oner locked his arms and gripped the steering wheel with brute force, fighting to stabilize the iron beast. He shot a rapid glance at the rearview mirror. Without waiting for Keria to process what had just occurred, Oner slammed his foot flat against the gas pedal, the engine roaring in a frenzy as the vehicle surged forward.
Keria spat out a curse, letting out a sharp, mocking laugh.
“Your mouth is a literal fucking jinx, you know that?!”
“Keria.” Oner’s voice turned instantly rigid. It was a rare occasion for him to address his friend directly by his codename in such a dead-serious tone. “Turn your head around and look at that thing.”
Keria immediately braced himself against the frame, poking his head out into the dust-choked window to look back at the path they had just traversed.
Amidst the swirling, blinding dust storm of the wasteland, a colossal entity stood towering over the terrain. Despite the rapidly widening distance between them, Keria could distinctly feel its deformed visage staring straight in the direction of their vehicle. The sensation sent a violent shiver down his spine, as though they were prey being scrutinized by an apex predator.
No... it was far more terrifying than that. It seemed Oner was enduring the exact same suffocating sensation. In his six years stationed at Citadel 1, facing all manner of Monsters, Keria had never laid eyes on a creature like this. The appearance of new mutations wasn't rare, but the crushing, suffocating pressure radiating from this thing was entirely unprecedented.
“You realize it too, don't you?” Oner’s face was pitch black, his eyes glued to the treacherous road ahead as he spoke in a raspy, strained voice. “We have an S-class Sentinel and an A-class Sentinel sitting right here... So tell me, why the hell did neither of us sense its approach until it hit us?”
Keria froze, a genuine, icy dread crawling up his spine.
A Monster capable of completely masking its existence from Sentinels?
[Classified Internal Data]
☬ The LCK Tower ☬
Personnel Dossier - Sentinel Registry
Citadel No.1
∆ Ryu Minseok - Sentinel
Codename: Keria
Classification: S-Class
Deployment: Citadel No. 1
Physicality: A | Combat: A | Mental Domain: A | Tactics: A
Feral Risk: 15% | Fugue Risk: 30%
∆ Moon Hyunjoon - Sentinel
Codename: Oner
Classification: A-Class
Deployment: Citadel No. 1
Physicality: S | Combat: A | Mental Domain: B | Tactics: B
Feral Risk: 64% | Fugue Risk: 73%