The atmosphere within the Abyssal Vein Dungeon was not merely hot; it was predatory.
Deep in the Silverwood Kingdom's subterranean frontier, the air vibrated with a sub-harmonic frequency that tasted of sulfur and ancient, unrefined mana.
The walls, slick with damp obsidian, were laced with pulsating crimson veins of ore that throbbed like the heart of a dying giant.
At the center of this lightless cathedral, a Rank-A Obsidian Demon loomed.
It was a colossus of jagged black plates, its armor cracked from previous exchanges but still radiating a lethal, oppressive heat.
Its eyes were twin pits of molten slag, fixed on the human standing before it.
Blade Lunaria stood firm, his vibrant crimson hair glowing like a torch against the gloom. He wore his signature red-and-gold leather adventurer's outfit, the fabric slightly scorched but the silhouette unmoved.
His red eyes—usually cheerful and expressive in the taverns of Valerion—were now sharpened into lethal pinpricks of calculation.
He casually spun his broadsword, its edge wrapped in tattered, magically-imbued cloth that shimmered with a faint, violet-black undertone.
"You are strong… human," the demon growled, the sound like tectonic plates grinding together.
"But the one who survives this abyss will not be you."
Blade tilted his head, a ghost of a smile touching his lips.
"I've heard that verdict from beings much higher in the hierarchy than you. We'll see."
The demon roared, raising both claws to weave complex, burning sigils in the air.
Circles of hellfire ignited around Blade, forming a blazing prison that turned the oxygen to ash.
"Abyssal Cataclysm!"
The ground split open. Spears of magma and waves of black flame surged toward him. Blade didn't flinch.
He extended a single hand, his movements precise and clinical.
"Flame Veil," he murmured.
An ordinary fire spell, or so it seemed to the observers.
But when the two forces collided, the explosion rocked the entire chamber, sending shards of obsidian flying like shrapnel. Smoke and soot devoured the air, yet when the dust settled, Blade stood untouched.
A thin, transparent film of mana—the "Soul Veil" in its adventurer form—had effortlessly redirected the heat.
"Hmm. You're stronger than most Rank-A demons," Blade noted, his tone flat. "I'll acknowledge that much."
At the edge of the clearing, Lance and Yuria stood trembling.
They were scorched, bloodied, and breathing in ragged gasps.
To the rest of the world, they were high-tier Silverwood adventurers; to the person watching through the mirror, they were pawns.
They downed mana potions with frantic movements, their eyes never leaving Blade's back.
"He's playing with that thing," Lance muttered, his silver-white aura flickering.
"We can't let him walk out of here, Yuria. If he survives, our master will have our heads. Now!"
Yuria extended both hands, summoning the Crimson Tempest.
Blood-red lightning arched from her fingertips, twisting through the air toward Blade's blind spot. Simultaneously, Lance charged, his sword cloaked in a blinding silver light.
Blade sensed the ripple in the mana before the sound even reached him.
His internal profiling—a remnant of the Dark Psychology he had mastered in Tokyo—modeled their trajectory in milliseconds.
"Predictable," he whispered.
He swung his sword upward in a sharp arc. A compressed shockwave of pressurized air burst outward.
The lightning veered off course, striking the cavern ceiling and bringing down a rain of stone.
Lance's strike, meant to decapitate, only grazed the shoulder of Blade's red coat.
Blade didn't wait for a recovery.
He kicked Lance square in the chest with enough force to crack his breastplate and redirected Yuria's follow-up spell with a casual surge of black-crimson flame.
"You should have disappeared quickly," Blade said, his voice dropping into a chilling register.
"Good. This just makes the data collection last longer."
---
Far away, in a chamber lit by the eerie glow of violet flames, the First Summoned Hero, Nyxarion, stood before a floating magic mirror.
He was a vision of divine authority, dressed in blinding white and gold raiments, his face half-hidden by a featureless porcelain mask.
His eyes, ancient and calculating like fractured glass, watched the battle unfold in the Silverwood dungeon.
"So… this is Blade," Nyxarion murmured. He watched the way the red-haired boy moved—the lack of wasted energy, the lack of fear.
"No—he's more than a lucky adventurer. I can feel it… the void coiling beneath that cheerful red mask. He isn't just a threat to the Demon Empire. At this rate… he might surpass even my 'False Peace'."
His expression hardened behind the porcelain.
"No. I won't allow a second darkness to stain my masterpiece."
---
Back in the dungeon, the Obsidian Demon let out a sound that wasn't a roar, but a scream of metaphysical agony. Its body began to glow with blood-red veins—the sign of a demon over-clocking its core.
"You insects! You dare mock a superior being?!"
It slammed its claws into the earth, and the chamber floor turned into a map of glowing runes.
"Oblivion Inferno!"
The entire underground hall shook. Walls began to melt into slag; the ceiling cracked, pouring molten stone onto the floor.
Blade straightened his coat calmly, his crimson hair reflecting the inferno.
"This… might finally be worth a test."
He dashed forward—breaking the sound barrier with a localized burst of wind magic. His sword ignited with a Dark-Crimson Flame, a hybrid of human elemental magic and the suppressed power of his Shadow Core.
Lance and Yuria tried to coordinate one last time.
"Yuria! Cover the left! Barrier Flame!"
But Blade was no longer where they were looking. He vanished into a glitch of reality, reappearing behind them like a ghost.
"You chose the wrong master," he whispered.
He unleashed the Dark Nova Slash—a silent, compressed wave of annihilation.
The chamber flashed a blinding white. Lance's sword shattered into metallic dust; Yuria's barrier cracked and exploded into shards of mana.
Both spies were hurled backward, crashing into the melting walls, coughing up thick, dark blood.
Blade's eyes glowed a faint, lethal red.
"I told you—you made two mistakes. But the third was believing traitors deserve mercy."
He raised his sword, the flames swirling around the blade like a crimson storm.
A single flash of black-red light followed. When it faded, the spot where Lance and Yuria had stood was occupied only by drifting ash.
The Obsidian Demon staggered forward, its mind broken by the loss of its servants.
"You dare kill my tools?!" It raised both hands, forming a massive, spinning sigil of death.
"Explosion of Death!!"
A sphere of blinding black flame formed in its palms, screaming with the sound of a thousand lost souls.
Blade watched it, his eyes narrowing. Within his mind, the Dark Psychology profile completed its scan. He didn't counter the spell; he analyzed its structure.
"That spell…" Dark runes ignited within his irises. "Copied."
An identical sphere of flame formed in Blade's palm—nearly perfect, equally violent, but fueled by a logic the demon couldn't comprehend.
"Let's see whose destruction has more weight."
They released the spells simultaneously.
The two fireballs collided in the center of the hall, merging into a catastrophic explosion that obliterated the very concept of the chamber. The shockwave flattened everything.
When the dust finally settled, only Blade stood.
His red coat was torn slightly at the sleeve, and his sword glowed with a dim, satisfied light. The demon knelt before him, half of its obsidian body disintegrated.
"What… are you?" it wheezed.
Blade looked down with eyes that were suddenly, terrifyingly empty.
"The shadow that judges arrogant monsters."
One slash. The demon's head fell, and the dungeon's core shattered like glass.
Moments later, the oppressive atmosphere lifted as the dungeon began to dissolve.
Light flooded the chamber from a prepared teleportation portal.
Guild Master Varun and the receptionist Mina stepped through, followed by a squad of high-ranking Silverwood knights.
"Blade-san!" Mina ran forward, her eyes wide with relief. "Are you alright?!"
Blade offered a tired, cheerful nod, the "Shadow" persona retreating back into the "Adventurer" mask.
"I'm fine, Mina-san. Just a bit of a workout."
Varun looked at the piles of ash and the shattered demon. He smiled grimly.
"We saw everything through the magic screen, Blade-kun. That Invisible Slime you created—it was a stroke of genius. It captured every word, every betrayal. Lance and Yuria… they truly were the rot in our guild."
He sighed, looking at the treasures now revealed by the dungeon's collapse.
"They deceived us for months. Adventurers were disappearing, and we were powerless without proof. Until tonight."
Blade sheathed his sword.
"Then use this as the guild's evidence. Justice should be public, even if it's delivered in the dark."
Varun nodded solemnly.
"Blade-kun… the entire Silverwood Kingdom—no, the continent—will soon know what the 'Hunter' has done here."
---
Flashback — The Morning Before the Dungeon
At the Esmoril Adventurers Guild, the sun had been pale and cold.
Blade had arrived before the doors even opened, finding Mina and Varun sharing a quiet coffee at the counter.
"Ah… Blade-kun," Varun had said, noticing the young man in the bright red outfit.
"You've been a rising star in this city, but we haven't spoken properly. What brings you in so early?"
Blade's eyes had narrowed, his cheerful demeanor replaced by a sharp, tactical edge.
"You want to clear out the traitors, don't you, Guild Master?"
Mina had gasped, looking around to ensure they weren't overheard.
"Blade-san, that's dangerous talk. You mean Lance and Yuria? We suspect them, but the Guild Laws require evidence before we can act."
Blade had reached up and tapped his right shoulder.
"The plan is simple. Do you see the slime on my shoulder?"
Both Varun and Mina leaned in. There, nearly transparent and perfectly still, was a tiny slime.
"How… I didn't see that before!" Mina exclaimed.
"What can a slime do?"
"This is my own creation," Blade explained, his voice low.
"An Invisible Slime with a sensory link. I've designed it so you can monitor my visual and auditory feed through a magic screen in the back office. If they betray me inside the Abyssal Vein, the Guild will have its proof in real-time."
Varun had looked at the boy with newfound respect.
"Amazing ingenuity, Blade-kun. Very well. We'll be watching. Don't die out there."
---
The Legend Spreads
Days later, the news moved like a wildfire through the kingdoms.
"Adventurer Blade cleared a Rank-A Abyssal Vein alone!"
"The traitors of Esmoril have been executed by the Red Hunter!"
"The Silverwood Kingdom declares Blade its strongest active Rank-A!"
From the taverns of Flarewood to the royal courts of Ironwood, the name Blade became a symbol of rising, unpredictable power.
In the Valerion Temple, Ryuto Yuzen read the report, his brow furrowed in confusion.
"Blade again… Why does his mana signature in these descriptions feel so… familiar?"
Nearby, Rei Nocturne lowered her gaze, a small, knowing smile playing on her lips.
"Shujin-sama… you've certainly found a loud way to stay hidden."
And far away, in the chamber of violet flames, a fist clenched so tight the stone throne beneath it cracked.
"Then the game begins in earnest… Darkness Lord," Nyxarion hissed into the silence.
---
✦ To be continued...