This Dungeon Grew Mushrooms

Vast and boundless, the open sea stretched endlessly as a massive, plain-looking sailing ship made its slow journey north.

Its hull was dark brown and utterly unadorned, appearing at first glance to be nothing more than an ordinary cargo vessel.

Only when one drew close could faint runes be seen carved beneath the wooden grain, and beneath the waterline, the barely visible glint of silvery metal.

Defense matrices, anti-detection wards, magic-concealing arrays, beast-repelling sigils, wave-sensing circuits…

Calling this ship the culmination of the Church’s magic array engineering would not be an exaggeration.

High above on the main mast, Sophia stood atop the spar, ocean wind tossing the gold hair tied behind her. Her eyes—enhanced through skill—stared toward the distant horizon. Square white lines pulsed in her pupils, zooming in and out as they projected far-off scenes directly onto her retinas.

“Still nothing?”

A brisk voice floated up from below.

Bella scaled the mast with feline ease, offering Sophia a softly glowing green fruit.

“Rest for a bit. Your eyes are going to dry out if you keep staring like that.”

In truth, the ship lacked no reconnaissance capabilities. Under Priest Samuel—master of magic array theory—the vessel’s detection matrices and anti-scrying wards were more than enough for most situations at sea.

However, all those refined arrays and intricate devices were eclipsed by one thing—Sophia’s eyes.

Vision exceeding mortal limits.

Sight piercing most illusions and veils.

And a brief ability to foresee trajectories a few seconds into the future.

Together, these made Sophia the irreplaceable “living radar” of this entire region of ocean.

Which was why, ever since they began hunting demon warships, nearly every moment she was awake had been spent on the mast.

Sophia accepted the fruit, and the strange white grid in her pupils slowly dissolved like ripples fading into still water.

“So far, the only ship we’ve successfully intercepted was that lone demon transport.”

She bit into the crisp, sweet flesh, her tone tinged with disappointment.

“Every other time, it’s been full demon fleets. We can only avoid them. If only the archipelago people were willing to help… then we might actually have a chance to cut off the demons’ sea routes.”

“Don’t count on those scum,” Bella snorted, full of contempt.

“Spineless fence-sitters! Expect them to openly oppose the demons? I’d sooner expect some ancient sea monster to appear out of nowhere and swallow the entire demon navy in one bite!”

Of course, that was just venting.

Powerful sea beasts certainly existed—some capable of capsizing entire fleets—but most had low intelligence and acted only on instinct: hunger and territory.

That was precisely why the ship’s beast-repelling array could emit a magical frequency strong enough to make most sea monsters avoid them.

And the demons, with their own formidable technology, would naturally have similar protections.

Meaning Bella’s “miracle” was practically impossible.

Sophia opened her mouth to reply—but her gaze drifted across the northern horizon and abruptly froze.

The white square in her pupils contracted to a pinpoint.

Her voice tightened:

“There are ships!”

Her warning instantly brought both the guard captain and Priest Samuel rushing up from the deck.

Sophia relayed what she saw:

“Northwest direction—three demon warships! One Siren-class, two Bone-class!”

“A Siren-class?!”

Samuel’s expression tightened.

By demon standards, their own vessel was roughly equivalent to a Bone-class.

But a Siren-class… that was one of the true sea giants of the demon navy, and a ship of that size would certainly carry at least one Sanctum-tier powerhouse—along with a full combat formation.

They could fight if necessary—but Samuel’s mission was to protect the Hero’s development. Hunting weak, isolated targets was acceptable. Risking a direct battle with a proper fleet was absolutely not.

He immediately prepared to slip away quietly, just as they had done many times before.

But Sophia raised a hand suddenly and spoke again—this time urgently:

“Wait—Priest Samuel! Something’s wrong… the defensive runes on their hulls are flashing repeatedly. It looks like… they’re being attacked by sea creatures?”

After reporting this absurd situation, Sophia instinctively turned to glance at Bella—expression suspicious—as if checking whether her companion really did have a hidden talent called 【Cursed Mouth】 that had just triggered in real time.

…

Meanwhile, on the demon fleet, the ships were indeed under attack.

But the attackers were not ordinary sea beasts.

A half-demon whose right arm had a bone blade embedded in its flesh steadied himself on the violently lurching railing and peered over the side.

The murky waters below were littered with bloody chunks—scaly severed limbs, unmistakably the remains of the serpentfolk soldiers who had been sent down earlier to investigate.

“What kind of sea beast is this?”

The half-demon yelled toward the bloodborn viscount farther down the deck.

“Sir! Looks like the entire first squad of serpentfolk is gone! What now? Should we have the mages freeze the whole damn sea?”

The ship’s runic wards flashed rapidly, but the half-demon’s tone showed little fear.

The ship’s defenses were excellent; no sea beast could breach them quickly.

Besides, the real trump card—Lord Hess—hadn’t even acted yet. There was nothing to fear.

KRRCH… SCRAAAPE…

A harsh scraping, like something rigid clawing along the hull, echoed out.

The half-demon tensed, scanned the surroundings—

—and saw nothing.

“You idiot! Duck your head!”

The bloodborn viscount roared—

—but his warning came too late.

The half-demon felt a sudden chill on his neck.

His vision twisted.

The world flipped—

And the last thing he saw was his own headless body still standing, blood jetting from the severed neck like a fountain.

His head fell into the sea with a splash—

—and the spraying blood outlined a monstrous silhouette clinging to the ship’s hull.

Six limbs.

Six claws.

A six-claw.

“Damn it…”

The viscount cursed both his subordinate’s stupidity and his own failure to detect the creature sooner.

He raised his gemstone-inlaid staff high.

A moment later, a shifting, multicolored sphere of light burst from the staff and hovered overhead like a miniature artificial aurora.

Under its illumination, the six-claws’ Refraction Cloak failed, revealing numerous hideous forms already crawling across the deck.

Battle erupted instantly.

Metal clashed against bone.

Claws tore through flesh.

Screams, growls, and wet impacts blended into a frenzy of sound.

Caught off guard, the demon soldiers still quickly regained formation thanks to superior training and equipment.

The six-claws’ stealth assault failed to inflict enough casualties in the opening strike.

Without the element of surprise, they soon fell behind under the demons’ brutal counterattack.

Until—

A massive tentacle, lined with teeth like a gaping maw, surged up from the sea and slapped onto the deck.

The whole ship lurched violently.

At the same time, two colossal sinister eyes rose from the waves—water streaming off them like tears.