This Dungeon Grew Mushrooms

Muling Fortress, the royal palace of the demon emperor, was guarded with extreme vigilance.

Multiple layers of defensive structures surrounded the outer perimeter, and the blood-crystal watchtower at the castle’s center kept everything within three thousand meters under surveillance. The slightest anomaly would trigger alarms and summon the elite Bloodguard stationed inside.

Just beyond the outer edge of that three-thousand-meter alert radius, inside the basement of what looked like an ordinary residence:

The old demonkin Ratir roughly dragged several bound demons to the ritual nodes, then tilted his head toward Tanaka, signaling for him to come up.

On the table in the basement, an hourglass was steadily draining — the time limit set by the fox-folk Kiro.

Only Tanaka’s Sloth clone was present; Kiro himself had left after setting everything up, not even bothering to appear.

Feeling the chilling aura seeping from the ritual circle beneath his feet, Tanaka looked uneasy.

“Abyssal magic… can this really work?”

Ratir sat at the edge of the ritual, glanced at the hourglass — still a little time left — and finally replied, “If you want an answer to that, ask that sly fox.”

“Speaking of which,” Tanaka hesitated, “I never asked you this. Why help Kiro? Or rather… why trust him?”

Ratir suddenly let out a hoarse laugh that echoed harshly through the basement. “I’ve only met him twice. Where would trust come from?”

“Only twice? Then why—”

“He showed me what he can do,” the old demonkin said, laughter vanishing and determination flashing in his eyes. “And I… simply chose to gamble.”

“And if he lied to you…”

Ratir shrugged with utter indifference. “Then I lose this rotten life, that’s all. At least I’ll cause that traitor some trouble before dying.”

His gaze returned to the hourglass. He slowly rose. “Time’s about up. Let’s begin.”

“Wait, one last question.” Tanaka pointed at another Abyssal magic circle in the room. “What is that one for?”

Ratir grinned, showing his teeth. “That one’s for me.”

The runes beneath Tanaka flared with pitch-black light. With the sacrificial victims’ short-lived screams, Tanaka’s figure flickered and vanished from the basement entirely.

At nearly the same moment, several Bloodguard were already racing toward the residence.

…

Tanaka’s vision flickered — the next moment, he found himself standing in a sealed room covered in arcane runes.

The chamber had no torches, yet every inch of wall, floor, and ceiling was carved with runes glowing faintly, providing a dim source of light.

He felt no threat or restraint. It seemed, just as Kiro had said, the rune effects only applied outside the room.

His attention instantly fell on the object sitting atop the central pedestal.

A flawless white cube — perfect in shape, without a single blemish. It starkly contrasted with the densely packed runes all around it, impossible to overlook.

“So this is the Demon King’s seal?”

Tanaka stepped forward — and his left foot was suddenly yanked down.

He glanced down.

His left foot had fused directly with the floor.

“What kind of game-engine bug is this…” He gritted his teeth and pulled, but the foot refused to budge, as though it had always been part of the ground.

He clenched his teeth and drew the short blade at his waist.

Steel flashed.

Blood sprayed from the severed ankle, staining the rune-carved floor a dark red.

“Damn fox bastard… this was your ‘perfect plan’?”

Enduring the agony, he hopped toward the white cube on one foot.

But when he was only one step away, an invisible barrier stopped him.

He pressed against the unseen wall, his expression turning uglier by the second.

“Kiro said there wasn’t any barrier inside!”

【Hero, restriction lifted】

Before Tanaka could react, all resistance vanished from before him. His hand slapped down onto the white cube.

The cube toppled — its shell cracking apart like a broken eggshell. A mass of pale-blue gel, speckled with faint starlike lights, slowly oozed out, glowing softly in the dim room.

“So I’m… the one who awakened it first?”

Tanaka stared blankly at the wriggling mass on the ground. “A slime?”

“Rude, young man. It’s ‘flow-gel being.’”

Then the jelly-like creature seemed to notice something. “This room is… amusing.”

Floating up into the air, the gelatinous being shifted the flow of magic in the chamber. One after another, the runes carved into the floor went dark.

It was dismantling all the room’s seals effortlessly — silently — and without triggering any alarms.

Tanaka hurriedly opened the panel, catching only the two most important details:

【Skill: The Apex of Arcana …】

【Title:

Demon King: Not restricted by race level. Can randomly draw one special title or skill (already used).

…】

When the final rune dimmed, the gelatinous being drifted down.

“You found a way to leave, yes? In my current state, I can’t take you with me.”

Tanaka nodded instinctively.

Receiving confirmation, the fluid creature shimmered with mana and vanished.

The final ripple of teleportation finally tripped Muling Fortress’s alarm system.

A shrill alarm echoed through the entire stronghold. Tanaka did not dare linger — he immediately dismissed his clone.

His body faded like morning mist, dissolving into the air without a trace.

When the Bloodguard burst into the chamber, they found only an empty pedestal and a room full of dead runes.

They sealed off the entire fortress and conducted a floor-to-ceiling search.

In the end, all they discovered was faint residue of Abyssal magic in a collapsed basement and traces of an elderly demonkin who had fled. Nothing more.

Meanwhile, hundreds of kilometers away inside a carriage—

“Ow-ow-ow-ow!! My foot!!”

…

Outside Tri-Mountain City, the blood-red canopy roared and boiled.

Mortis sat upon his blood throne; with a flick of his hand, endless waves of blood surged and condensed into countless blood-crystal spears, each packed with terrifying power.

The blood spears rained down like a crimson storm, turning the entire battlefield into a forest of scarlet lances.

The shrill sonic booms tore through the air; the ground trembled violently under the relentless barrage.

The werewolf-transformed Elvien darted between the spears. His body had swollen to three meters tall; his silver-gray fur had been tinted dark red by the bloodlight, and each of his claws gleamed like forged steel.

Right now, his claws were the sharpest swords.

The five bone-deep claw marks across the prince’s chest were struggling to heal — only because Valerius had reacted fast enough.

When the Sword Saint burst out from the crystal cluster, Valerius had been the first to charge in, and had nearly been torn apart for it.

Elvien was extremely cautious now. Aside from The Pinnacle of the Sword, he did not use any techniques.

Even though Mortis was no longer using Envy to interrupt him, Elvien still remembered well how his Moonstep had been forcibly shattered.

The only thing he could trust was The Pinnacle of the Sword.

Elvien didn’t rush Mortis directly — he kept dodging between the blood spears, searching for an opening.

But the result was disappointing.

With the artifact Bloodbane in hand, Mortis completely enveloped himself within the blood veil, leaving not a sliver of opportunity.

As if bored of the chase, the emperor clicked his fingers. Another sky-piercing blood pillar descended, joining the barrage of spears as the rhythm of the battle sharply intensified.

At that moment—

A ring on Mortis’s right hand shattered, its magic scattering like stardust.

“The sealing chamber!”

That brief distraction opened the smallest flaw in the perfect blood veil.

It was enough.

Elvien shot forward like a silver bolt of lightning, claws ripping through space toward the emperor’s throat.

Simultaneously, countless blood-crystal spears materialized above Mortis’s head and launched in counterattack.

As they crossed paths, three claw marks appeared across the emperor’s neck, dark-red blood seeping slowly.

And the Sword Saint, skewered through by dozens of spears, fell helplessly from the sky.