The Royal Military Academy's Impostor Owns a Dungeon [BL]

Splashhhhh—!

Metal crashed into the sea. The surface split open as Sera’s mecha plunged into the dark water, a surge of bubbles and foam bursting upward.

Inside her cockpit, Sera gripped the controls, eyes darting across the radar. ”Nia! Respond!”

Static.

Only static.

Her radar blinked wildly, showing distorted signals all around her. The water was too murky, churned into chaos by the force of their descent. Silt, sand, and fragments of coral filled the view screen, turning the ocean into a gray storm.

She clenched her teeth, pushing her controls. ”Come on, come on... where are you—”

Beep. Beep. Beep.

A faint signal blinked on her screen.

”Nia, hold on, I’m coming!”

Her comm crackled. Then a strained voice broke through, distorted but unmistakable.

”Don’t—don’t follow me!” Nia’s voice was panicked, breathless. ”I’m serious, Lieutenant! You have to report this—whatever HQ thinks the rebels are doing, this is worse! Way, way worse!”

Sera’s blood ran cold. ”What are you talking about? Where are you?”

In truth, Nia didn’t know how to answer because all she saw was a never-ending carpet of what surely looked like tentacles!

Worse still, the mecha wasn’t functioning as it should.

”My mecha’s leg was suddenly unresponsive! But I’m currently being pulled downward!”

Metal groaned through the line. The radar blip began to sink.

”Nia! Hold on!”

”Don’t come closer!” she screamed. ”You can’t see it, but I can—it’s huge! Tell them—”

”This is so far beyond our pay grade!”

The signal died.

Only static filled the cockpit.

But not seeing it? No. At least, not anymore.

Sera couldn’t see it earlier because she didn’t know what she was looking at.

Because now that the water had settled, how could she possibly miss this monstrosity?

Static filled the comm line.

Sera’s voice came through, breathless but clear. ”Nico, I’m sending an image now. Get everyone you can because what in all the stars is that supposed to be?!”

Right about now, she even felt like asking for priests, maybe even exorcists.

Sera, however, didn’t wait for a reply. More like she really could not after hearing what happened to Nia.

Her thrusters flared, cutting through the murky waters as she dove after Nia’s last signal. Inside the cockpit and while entering stealth mode, she prayed to the gods to lend her the ability to use the mecha she was piloting, even if just temporarily.

Her mecha’s systems dimmed as she reduced its energy output, quieting her presence the way she’d practiced. The water churned softly around her as she descended, her hands trembling on the controls.

Back at the command hub of Sector One, Nico’s console flashed just as he tried calling for Sera’s name.

He opened the incoming transmission—and froze.

The image was murky but sharp enough to make his stomach twist. The shot came from Sera’s mecha.

And there, suspended in the frame, was something colossal.

At first, it looked like a field of tendrils swaying in the dark—thick, curling tentacles that moved in rhythmic waves. Some looked smooth and rope-like, while others were jagged, branching apart, and looked much more menacing than the rest.

But then, his eyes caught the worst part.

At the edge of the frame, he could see Nia’s mecha—tiny in comparison—being dragged down by a single tentacle.

It looked helpless.

The limb wrapped around it like a child holding a toy.

And beyond that, where the light barely reached, the water shimmered faintly with movement. It wasn’t just one creature. It was... layered. The tentacles were part of something bigger—something that stretched so wide, the image couldn’t even capture the full form.

It was like looking at a giant carpet of flesh, pulsing with life, its surface glimmering under the weak bioluminescent glow of the deep.

And close by, there was a crater—a ginormous hollow pit.

Except it wasn’t a pit. It had to be a mouth, especially if all those creatures being deposited inside were any indication.

The readings flickered on Nico’s screen, numbers jumping erratically. If those readings were even half right, that ”mouth” was large enough to swallow an entire structure.

His throat went dry.

”...You’ve got to be kidding me.”

The image feed ended abruptly, replaced by flat static.

”Sera?” he called out. ”Lieutenant Rivers, do you read?”

Nothing.

He tried again. ”Nia? Sera?”

Still nothing.

The silence stretched, practically suffocating him who had just spoken to two of his most important people, only to face this silence now.

Then Nico slammed his palm against the console, opened a direct line to Military HQ, and shouted, ”We have a situation in Sector One! We’re facing a biological anomaly of impossible scale! Send reinforcements—now!”

The operator on the other end stammered. ”Define anomaly, Captain.”

Nico stared at the frozen image still on his secondary screen—the faint silhouette of a mecha being pulled toward that glowing maw.

He swallowed hard.

”Something alive,” he said. ”Something big enough to make the sea itself look too small.”

And maybe that was just the problem, for what could be done when it had taken everything under the sea?

__

Back at the Military HQ Command Center, Deputy Officer Curtis was glad they had found the anomaly, only to nearly fall over when he saw what it was.

”Sir! I think we found it!”

Marshal Julian entered at that exact moment, his heavy boots thudding against the floor. ”Where?” he asked sharply.

”Sector One Zone Four, Sir.”

Curtis pointed at the main screen, stammering. ”The creature causing the anomaly, sir. We have visual confirmation. But uh... Sir, you might want to sit down for this.”

But Julian didn’t sit down.

He leaned in closer, eyes narrowing as the footage came into focus.

For a long moment, there was silence as Marshal Julian absorbed the reality of the situation. Just static, faint sonar pings, and the sound of the Marshal’s slow exhale.

”...What in the stars is that?” he muttered.

Curtis swallowed hard. ”That, sir, is what was likely causing the sudden change in water elevation. It was apparently underwater and wouldn’t have been detected if not for a mecha pilot mentioning her observation.”

Julian’s jaw tightened. ”And where are the pilots who discovered it? We need to get more information.”

Curtis’s voice faltered. ”That’s... the problem.”

Julian turned to him, his tone deadly calm. ”Problem?”

Curtis straightened like a man about to face his execution. ”Two of our mecha pilots are currently entangled with that thing. We lost contact during the scan relay.”

The Marshal’s expression darkened. ”What?! Who?”

Curtis grimaced. ”Sergeant Nia Kane and Lieutenant Sera Rivers.”

Julian froze. ”Rivers? As in Lieutenant Sera Rivers?”

Curtis nodded, visibly sweating. ”Yes, sir. The one piloting the prototype support mecha built by that genius mechanic, Luca Kyros.”

The room erupted in gasps and low murmurs. The name alone was enough to cause panic. Luca’s mecha wasn’t just another model—it was presently the only one of its kind.

Julian slammed his palm on the table, silencing the room. ”Enough. Divert the forces from the nearest zones to Zone Four immediately. I want every available rescue and combat team sent to Sector One.”

”Yes, sir!”

Curtis moved fast, barking orders into the comms. Across the facility, alarms began to blare—sharp, echoing, and relentless.

WEEOO—WEEOO—WEEOO!

Lights flashed crimson as automated announcements played through the corridors. ”All units, prepare for emergency deployment! Repeat, all units, prepare for emergency deployment!”

”This is Marshal Julian,” he said, his voice low but steady as the line connected. ”Your Majesties, I’m contacting you regarding a critical situation in Sector One, Zone Four. We’ve confirmed the existence of a calamity-level monster. Two of our pilots are already engaged, including Lieutenant Sera Rivers, currently operating Luca’s support-class mecha.”

There was a pause on the other end. Then the Emperor’s voice came, sharp and incredulous. ”We’ll get there as fast as possible.”