Crossover Shipgirls: Building a Dimensional Empire from Scratch

Both sides of the ongoing battle momentarily froze as the enormous starships suddenly appeared overhead.

Like any pre-space-age civilization, they were momentarily stunned by the sight of colossal warships blotting out the sky.

Boom—

The mass-produced ships of the Fleet of Fog lacked Klein Fields, and under the combined assault of the Eternal Snowfall and the Sakura Empire fleet, they were swiftly melted down into scrap metal by high-energy beams, dissolving into molten iron on the ocean surface.

”Aliens?!”

”Am I dreaming? Could it be the Eagle Union… no, is it another nation coming to our aid?”

On the transport ship, the captain responsible for escorting the vibration warhead looked up at the starships in excitement.

He had resigned himself to certain death today, only to be unexpectedly rescued by what seemed to be extraterrestrial forces.

Squinting through his binoculars, he tried to identify the origin of the starships.

But neither their flags nor their ship models resembled anything he had ever seen.

”Is this really something Earth could have built? Where the hell did they come from?”

”If not the Eagle Union, then could it be Britannia? Or the European Union?”

”Forget it, forget it. Regardless of which country they belong to, if they have ships like these, then the war against the Fleet of Fog should be over soon… they’ll wipe them out in no time…”

Just as he was rejoicing—

The crew suddenly noticed that two larger Siren shipgirls, along with a vast number of mass-produced Siren units, were descending from the Eternal Snowfall.

Among the Sirens, the Executor-class units ranked below the experimental units but above ordinary mass-produced models, serving as mid-tier combatants.

They possessed both humanoid forms and riggingging, were far more agile than mass-produced ships, and could conduct boarding operations. However, their autonomy was limited—they had to obey the commands of experimental units.

That meant Purifier and Observer were leading them.

”They’re really aliens?! And they’re all girls?!”

”They can walk on water?!”

The human fleet watched in astonishment as the Siren shipgirls strode across the ocean’s surface, riding the waves.

All of them had the same white hair and golden eyes, their faces strikingly similar, and their riggings exuded an aura of high-tech sophistication.

It was clear at a glance that they were an elite alien strike force.

”Hey! Over here!! Save us!!”

”Watch out for the Fleet of Fog!!! Help!!!”

The crew eagerly waved toward the Sirens.

Alien beauties were much easier to accept compared to tentacled monstrosities.

They considered themselves lucky that these weren’t some kind of eldritch horrors.

Then—

Bang! Bang! Bang!

Dozens of Siren shipgirls boarded the transport ship.

”Search for the vibration warhead and any usable technological data.”

The leading Executor issued orders with an emotionless expression.

”Eh?”

Before the crew could react—

The Sirens swiftly tore through the deck, making their way deep into the ship’s hold, where they found a small modular missile encased in a sealed alloy container, roughly three to four meters long.

Alongside it were a briefcase and a laptop containing the corresponding technical data.

This was the special anti-Fog weapon developed by the island nation at the cost of its entire national research effort.

As for the encryption protecting the data, the Sirens didn’t even care. The computing technology of a mere pre-space civilization posed no challenge to them.

”I thought you were here to help?!”

The captain was dumbfounded.

What the hell—so these aliens weren’t on their side?!

First, they annihilated the Fleet of Fog… and now they were looting the vibration warhead?!

The classic ”I want it all.jpg” moment.

Driven by duty, he drew his handgun and stepped in front of the Siren carrying the warhead.

With righteous indignation, he declared:

”This is classified technology! No one is allowed to—”

”Hmm?”

The Siren shipgirl turned her head.

-Clank—

Every gun barrel on the shipgirls’ rigging turned toward him.

Even if the captain didn’t understand what riggingging was, he could tell from the shape that these were definitely some kind of firearms or cannons.

”...”

Gulp—

The captain immediately calmed down, swallowing nervously.

”I mean, please handle it with care.”

”This thing is worth a fortune.”

”Oh, understood.”

The lead Siren shipgirl nodded.

”You’re actually pretty reasonable.”

Meanwhile—

Takao stared at Observer and Purifier in front of her.

She had absolutely no idea where these two had come from or what those bizarre riggings they carried were.

The massive fleet of hovering starships in the sky only deepened her confusion.

”Commander, don’t interfere. I want to see how strong the so-called Fleet of Fog really is.”

Observer, sitting atop her octopus-like rigging, contacted Setsuna.

”The combat data from this fight will be invaluable research material.”

”Do as you please, just don’t sink her.”

Setsuna and the other shipgirls remained in the air, watching the battle below like a cockfight.

He was quite curious about Observer and Purifier’s abilities. Ever since they had joined the port, he had never seen them engage in a serious fight.

”Relax, I promise to clean her up nicely and deliver her to your bedroom in one piece.”

Observer made an extremely questionable remark.

”...”

A hostile force.

Takao quickly assessed the situation.

”You… possess the ability to control warships, but I don’t sense any Mental Models from you. You are not Fog.”

”Who are you? Why are you here?”

She stood at the bow, looking down at Purifier and Observer below.

”I want to inspect your body. Won’t you be a good girl and surrender?”

Observer raised her hand in a mock question.

She muttered under her breath:

”Even the Tribunal faction hasn’t seen shipgirls from other worlds before… If we contact them later, they’ll be in for a surprise...”

Boom—

Takao didn’t respond. Instead, she fired her fully charged Super-Graviton Cannon.

Shua—

A crimson energy surge tore through the sea like a laser, aiming straight for the two Sirens.

”Ohhh—”

Purifier and Observer reacted with impressive speed, easily dodging the attack while seated atop their riggings.

Boom! Boom! Boom!

Both of them retaliated, opening fire with their ship cannons.

Shua—

Takao activated a semi-transparent blue energy shield, deflecting all incoming shells.

Some exploded upon impact, while others were harmlessly redirected, their trajectories bending away from her.

”So this is the Klein Field? Interesting.”

Observer analyzed the white-dress-clad shipgirl before her.

She had never encountered such technology in the Azur Lane world. While Sirens also had energy shields, the Fleet of Fog’s version operated on entirely different principles.

Instead of relying on a reactor’s energy output, it seemed to function primarily through computational power.

”Die.”

Takao waved her hand.

She decided to eliminate these two strange opponents immediately.

Clack-clack-clack—

Dozens of missile silos opened along the black-and-red warship’s deck.

Shua—Shua—

Dark-red corrosive missiles streaked through the air, locking onto the two Sirens.

At the same time, eight larger, torpedo-like projectiles—about a dozen meters long—launched from the sides, speeding toward them underwater at several times the speed of sound.

This was the most powerful weapon of the Fleet of Fog aside from the Super-Graviton Cannon—something humanity couldn’t understand, let alone replicate.

Buzz—Boom—

The Corrosive Torpedoes detonated upon impact, creating massive dark-red spheres hundreds of meters in diameter across the ocean surface.

Unlike conventional explosions, there were no dazzling effects, no mushroom clouds, nor thunderous booms.

Instead, anything caught in the blast—Fleet of Fog warships, Siren Executors, even a portion of the seawater itself—was simply erased, as if someone had gouged out a chunk of reality itself.

This wasn’t just explosive damage like that of regular torpedoes. The torpedoes directly affected the fundamental structure of matter, shattering and annihilating particles at a subatomic level.

In an instant, the battlefield was eerily empty—no wreckage of human warships, no remains of Fleet of Fog vessels, just an unsettling void where they once were.

”Whoa—”

The shipgirls watching from above were stunned, with Akashi staring wide-eyed in fascination.

They could feel the technological superiority of the Fleet of Fog’s weaponry.

Leaving aside the fact that their cruisers had missile silos, the sheer destructive power of the Super-Graviton Cannon and Corrosive Torpedoes was leagues beyond conventional weaponry.

While their range wasn’t particularly large, the way they inflicted true damage, breaking down matter on a fundamental level, made them almost impossible to defend against.

”Damn, humanity really stood no chance against these guys, huh?”

”Their weapons tech seems way more advanced than yours—uh, assuming we don’t count Wisdom Cubes.”

Gudako tilted her head in thought.

She wasn’t well-versed in technological warfare, but from sheer spectacle alone, the Fleet of Fog’s capabilities were overwhelming.

The special effects were maxed out—pure light pollution on an absurd level.

”Meow... But have you ever considered what would happen if we combined their tech with the power of Wisdom Cubes?”

Akashi twitched her ears.

”Oh! That’s a great idea!”

The shipgirls’ eyes gleamed with excitement.

Takao observed the battlefield, now cleansed by her Super-Graviton Cannon and Corrosive Torpedoes.

Nothing remained—not even the strange Siren girls from earlier.

”Tch—”

”It’s over.”

”That’s it? That was pathetic.”

She scoffed, adjusting her turret angles to take aim at the starships hovering in the sky.

It seemed they weren’t as formidable as they appeared.

Then—

A playful voice echoed from beneath the ocean’s surface.

”Miss shipgirl from another world, we were just toying with you~”

”Mmm, but your equipment and Mental Model are certainly fascinating. You’ll make a great research specimen.”

The voice came from directly beneath her.

Takao’s eyes widened in shock as she quickly activated her radar and sonar—

Two figures were approaching from below.

One resembled a shark.

The other, an octopus.

The Sirens’ riggings always had a slight resemblance to marine creatures, allowing them to move freely both on and below the water’s surface.

”???”

”You were submarines all along?!”

Before she could react—

Boom!

Muffled explosions erupted from below.

Purifier’s main cannons, over a dozen in total, fired simultaneously underwater, shaking the entire battlefield.

Boom—Boom—Boom—

The Klein Field’s saturation threshold was instantly exceeded, and the pale-blue energy barrier shattered spectacularly.

Takao’s propulsion system was the first to be disabled, and a gaping fracture tore through the middle of her hull.

The force of the impact sent her tumbling helplessly into the ocean.

”What… just happened…?!”

”Why…?”

Just before losing consciousness, she caught a glimpse of a white-haired, golden-eyed Siren loli swimming toward her—

The loli’s rigging, still brimming with writhing tentacles, wrapped around her.

”Purifier! You hit her too hard!!!”

”If you break her, Commander’s gonna punish us!!!”

Observer scolded Purifier while blowing bubbles in the water.

”…Cold.”

”Oh no. I’ve been captured by tentacle aliens.”

Takao’s mind could only latch onto one thought.

”Are they going to do… weird things to me?!”

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