Transmigrated as The Forgotten Extra-Chapter 126 Boss in the Ravine.

The dim crimson glow of the monsters’ cores and the echoing sounds of their movement at the bottom of the ravine showed no sign of stopping. What had once been dozens continued to multiply, without any indication that it would end.

Cain ground his teeth and holstered his pistol. He shifted his grip instead to the katana at his left waist. His sharp eyes narrowed as he tried to count the enemies surrounding them.

’More than thirty, and they’re still increasing. Is this place their nest?’

Most of the creatures encircling them were intermediate-rank virus beasts, towering crab-like monsters with elongated bodies and massive pincers for arms.

Considering that this ravine connected to a sea route, it made sense that it had become their nest. Not only was it difficult to access, but the darkness also concealed their presence perfectly, allowing them to ambush prey.

And Cain had foolishly walked straight into it.

He clicked his tongue in frustration. His lack of information about this world and about the virus beasts had led him into this nightmare.

He still didn’t fully understand his enemies, and that ignorance had dragged him into a deadly situation.

Suppressing his breathing, Cain glanced toward the stone staircase carved into the ravine wall.

’There’s still a chance! What about the stairs?’

But the moment that thought crossed his mind, the virus beasts seemed to read it. They moved swiftly, sealing off the cadets’ escape route.

"As expected of crabs, those legs are fast."

His mocking remark made Rika snap back sharply from behind him.

"This is not the time for jokes, Cain! What are we supposed to do?!"

Her raw anger rattled his eardrums. Cain let out a long breath, releasing the tension binding his body.

He fell silent. His right hand blurred as it tapped the small screen of his smartwatch several times.

In front of everyone’s eyes, his armour suit hissed and dissolved, breaking down into nano-particles that crawled across his skin before returning to the black bracelet on his right wrist.

"Cain, what are you?!"

"Cain?!"

"Leader?!"

"..."

Rika, Abel, Louise, and Peter stared at him with narrowed eyes.

Cain, however, focused only on the blue holographic panel floating directly before him.

[Corruption +1%]

[Corruption +1%]

...

The corruption value surged rapidly thanks to his new Limit Break skill, which absorbed cosmic virus energy faster than any known source.

Cain inhaled deeply, keeping watch on the monsters, who, strangely, remained still, as if waiting for the humans to move first.

Perhaps they were giving their prey one final chance to struggle before devouring them.

If so, they were gravely mistaken.

In a single breath, Cain drew his katana. The silver blade gleamed in the darkness, shining like a moon guiding the lost.

Gripping the hilt with both hands, he spoke calmly.

"You all hold your ground here. I’ll take care of everything."

"What are you saying? We should..."

Before Rika could finish, Cain cut her off. His gentle voice carried a chilling edge, far more terrifying than their surroundings.

"Limit Break."

[Corruption 100%! Conditions are already met to unleash the skill.]

[All your parameters will be X5 for the duration: 71 seconds]

The moment the words left his mouth, a black aura erupted from his body. The air grew heavy as small arcs of black lightning roared outward, spreading with terrifying precision.

But instead of retreating, the crimson glow within the monsters’ cores deepened, overflowing with greed and instinctive hunger to absorb elemental energy and evolve.

Raw, untamed power surged through Cain’s veins, making the veins on his knuckles twitch violently.

He took a deep breath, feeding oxygen into his lungs. The boy tried to calm the furious pounding of his heart.

The scattered black lightning crackled with fury, then condensed into a thin yet powerful layer that enveloped his body.

"Rika, Senior Luna, and everyone. Take your battle positions. If it becomes impossible, retreat toward the stairs."

Without wasting another second, Cain stepped forward and vanished into the darkness. His katana flashed sideways, cleaving into a metal crab that hadn’t even realized what was happening.

The motion didn’t stop there. Following the momentum of his first strike, Cain stepped forward and swung his Ether-wrapped blade, slicing through the enemy’s hardened metal body like jelly, without the slightest resistance.

There was no sound of clashing metals, only the dry thud of dismembered iron sliding to the ground, echoing at the end of Cain’s path.

Within his grey-toned world, Cain’s katana danced vertically, diagonally, and horizontally, rising slashes, all executed within a single breath. Several intermediate-rank virus beasts collapsed instantly.

’No... this still isn’t enough.’

Though their numbers dwindled, it was still below his expectations. Cain glanced to the side, at the blue panel displaying his remaining time.

[Remaining Time: 62 seconds]

’More. I can go faster.’

His trained body responded to his will. Cain’s breathing slowed, his face devoid of any emotions, and his black eyes reflected only the enemy forward.

A fragment of memories replicated in his brain, like a movie. The boy’s eyes flickered with a cold glint as he discarded unnecessary movements, minimizing his energy in every swing.

One by one, his body began applying the basic Kenjutsu principles stored in his mind. It was not like in the practicum, where he would take months or years to master. But it was forcibly enacted into his body.

Thanks to that, where he once defeated two monsters per second, Cain could now cut down three, sometimes four, when the enemies were close to each other.

The difference sounded small, but the gap was enormous.

Cain moved like a shadow, leaving afterimages and heaps of shattered metal in his wake. The silver gleam of his blade danced across the ravine floor like neon streaks cutting through the night.

Sparks flew as both metals scraped, black liquid reeking of rot flesh splattered across the ground, fueling Cain’s urge to press forward, to break through the invisible wall before him.

Then, amid the chaos, salvation arrived for those who refused to fall.

[Integrity Sync Complete.]

[Integrity 100% Reached]

> Level Up → 32.0

> Parameters boosted → All stats +1

> Bonus Point 5!

Cain, submerged in absolute focus, felt his heart thunder violently. Warmth spread from that pulse, reinforcing his flesh and bones to another height.

Within the battle, he snapped his eyes open, scanning the remaining enemies as he tightened his grip on the katana.

’How much time left?’

[Remaining Time: 50 seconds]

In that moment, reality and instinct blurred. Cain’s body absorbed information and adapted at an abnormal rate, turning the disadvantageous battle into a one-sided slaughter.

[Integrity +2%]

[Integrity +2%]

...

The numbers no longer mattered. Cain focused solely on maintaining the flow he had created from the first strike.

Seconds passed in pure sharpness. A final metal crab split cleanly in two, marking the end of the fodder enemies.

[Integrity Sync Complete.]

[Integrity 100% Reached]

> Level Up → 33.0

> Parameters boosted → All stats +1

> Bonus Point 5!

For a moment, a silence embraced Cain’s figure as he stood in the innermost part of the ravine, facing a towering rock cliff. He exhaled the tension in his body and whispered.

’I need to go back!’

Ignoring the blue panel hovering in his sight, Cain turned his body and tried to help his teammates. Yet, suddenly, he halted his steps when a chill seized the back of his neck.

"What?!"

His eyes widened. Without thinking, he leapt away before a massive stone spear slammed into the ground where he had stood.

Cain froze mid-breath as a mountain of rock before him rumbled. The mass shifted, firing seven identical stone spears into the ground before lifting its enormous body.

Cracks spread across the giant stone formation. Cain assumed his stance, preparing for a colossal foe.

A deafening crack rang out as the surface collapsed, raining stone fragments and forcing Cain to leap backwards to escape the rising dust.

Visibility vanished beneath swirling debris and darkness. Cain held his breath, waiting for the dust to settle, but the enemy did not allow it.

Suddenly, a black spike thrust toward him. Its razor tip dripped with black liquid, sending a chill down his spine.

Cain raised his katana. The spike collided with the blade, producing a screeching hum that shredded his hearing and sent sparks flying.

He had underestimated the force. Before he realized it, his body felt weightless, and then he was flung backwards.

Cain spun midair, landing atop the remains of a defeated metal crab, but the momentum carried him several meters before he finally stopped.

He exhaled sharply, staring at his trembling hands.

’That’s heavy.’

The loud screeching roar drew his attention toward the dust cloud.

A moment later, a piercing cry reverberated through the ravine. It sent a shockwave that blasted away the dust to reveal the monster before Cain.

The violent gust forced Cain to shut his eyes briefly. When the air cleared and the grit faded, his eyes opened slowly. His body stiffened.

Unconsciously, Cain tightened his grip on the katana. His breathing grew heavy, his vision narrowing as he stared at the towering monster clad in thick layers of iron.

Silence stretched. Then his hardened expression cracked into a fearless grin.

"So... you’re the boss of this place, huh?"