Crossover Shipgirls: Building a Dimensional Empire from Scratch

Before setting out, Setsuna and the shipgirls had already evaluated the strength of the enemies in this world.

The conclusion: they could win just by auto-attacking. The Abyssals had absolutely no means of countering the starships; they might not even be able to defeat an Angeloid.

The technological gap between their weapons and equipment was immense. No matter how strong the Abyssal princesses were, they couldn't bridge the chasm between the pre-space age and faster-than-light civilizations.

As such, the task of eliminating the Abyssals was divided among the shipgirls accompanying Setsuna.

The next morning—

The harbor in front of the Naval Base was bustling with shipgirls.

Azur Lane, Arpeggio, and KanColle natives had all gathered, discussing the routes for their deployment.

Whoosh—

With a wave of his hand, Setsuna projected a massive holographic map in front of them, drawing exclamations of awe from the native shipgirls.

"Judging by the positions, the Abyssals here are mainly concentrated in six sea zones. Each zone has roughly one to two thousand units."

"Most of them are mass-produced types, but some include elite-level Destroyer Princesses, Light Cruiser Princesses, Battleship Water Demons, and so on."

On the hologram, the entire planet's condition and the general distribution of Abyssals were clear at a glance.

Much like the Siren fleets, which are divided into low-level mass-produced units, mid-tier Executors, and high-tier Testers and Arbiters, the Abyssals also had a strict internal hierarchy.

The most common were mass-produced destroyers resembling fish, semi-humanoid light cruisers, light carriers, etc.

Though individually weak, they were formidable in swarms.

Some elite-level Abyssals had special titles like "Demon," "Princess," "Water Demon," and so on—such as Destroyer Princess, Light Cruiser Princess, Battleship Water Demon, Carrier Demon, etc.

These named Abyssals were usually mini-bosses of their sea zones, vastly more powerful than regular ones, and far beyond what the native shipgirls could handle alone.

Hiss—

Seeing the map, the shipgirls of the Naval Base were shocked by the sheer number of enemies.

With their current strength, never mind eliminating all Abyssals—they'd struggle to even reclaim a single sea zone.

"This... the situation is dire..."

KanColle Nagato furrowed her brow, carefully analyzing the enemy markers on the map.

As the former flagship and acting commander, she quickly considered several strategies in her mind.

"We currently hold an intelligence advantage. First, we should try to avoid enemy main forces and open a supply route to other zones."

"Once the Naval Base is properly resupplied, we can unite our strength and attack from the enemy's weak points, gradually eliminating the Abyssal strongholds one by one."

"Mr. Setsuna, if we all work together, I'm confident we can defeat them. I estimate we can take down the first base in about two months..."

She pointed across the map as she spoke.

"To prepare for a long campaign, we should also reinforce the Naval Base's surrounding waters..."

Her tone was serious and her planning thorough. She carefully analyzed every angle and laid out a cautious battle strategy.

The native shipgirls nodded in agreement.

"A sound plan—concentrate forces, prioritize weak points, and proceed steadily to shrink the Abyssals' area of operations."

Yamato nodded.

"?"

Setsuna blinked.

"Two months? A long campaign? What are you talking about?"

"This isn't a matter that'll take two or three days to solve?"

He realized the native shipgirls were still operating under outdated tactical assumptions.

"Huh???"

Under Nagato and Yamato's confused stares,

Setsuna began issuing commands to the shipgirls he had brought with him.

"Richelieu, Taihou, Nagato... each of you take a squad and wipe out one of the Abyssal strongholds."

"Bismarck, you and the Iron Blood fleet will handle the roaming Abyssals on the open sea."

"Understood!"

Shua shua shua—

The shipgirls materialized their hulls.

One after another, sleek sci-fi starships appeared over the Naval Base, leaving the KanColle shipgirls stunned.

"W-What about us?"

"What do we do poi? Do you need us to support you poi?!"

The native shipgirls realized Setsuna hadn't planned to involve the Naval Base's forces at all. He intended to handle the Abyssals completely on his own.

"You can have some tea, take a bath, and wait here for our good news."

Setsuna thought for a moment.

"No!"

"How can the Naval Base stand by while the enemy is here?!"

Yamato firmly refused, insisting on joining the expedition team.

"..."

Setsuna looked at her.

"Alright then, if you really want to come, you can join—as cheerleaders."

...

Whoosh—

The Azur Lane shipgirls set out from the Naval Base in all directions.

The starships, powered by anti-gravity systems, slowly lifted off and cruised in the upper atmosphere.

Inside each Azur Lane shipgirl's hull were a few native KanColle shipgirls.

Having never seen such advanced technology before, they were thrilled—nervous, but overjoyed.

"So big!"

Upon entering the interior of an Azur Lane shipgirl, the native shipgirls immediately felt the overwhelming gap between them.

Even the smallest destroyer was several times larger than Yamato, the Naval Base's flagship.

The hulls of carriers and battleships were several kilometers long—impossible to see end to end.

And as for the tech inside, the native girls didn't recognize a single device.

"This is the sensor array, that's the holographic scanner, and over there is the Klein Field monitoring system..."

Richelieu enthusiastically explained, flooding the locals with strange new terminology that left their heads spinning.

Vmmm—

Soon, a large Abyssal fleet appeared beneath the starship, sailing across the sea.

Hundreds of destroyers and cruisers patrolled the waters in tight squadrons, wrapped in thick black fog and looking utterly sinister.

At the center of the fleet stood a larger figure—a black-haired, red-eyed Abyssal princess in a black dress, her pale skin stark against her surroundings.

Behind her, her rigging took the form of a twin-headed beast, her chained hands flanked by two triple-mounted turrets.

The beast's skin glowed red-black and knelt behind her—not so much a rigging as a subordinate entity.

"Battleship Water Demon!"

"That's the Battleship Water Demon!"

Onboard the ship, the KanColle shipgirls cried out.

"She's one of the strongest battleships among the Abyssals! The Naval Base once encountered her during a patrol—Nagato, Mutsu, and the others were seriously wounded just to escape!"

"She's very dangerous poi!!!"

The bridge filled with unrest as the native shipgirls recalled their traumatic memories.

Below, the Battleship Water Demon looked up with confusion as the starship loomed closer.

At first, she mistook it for a large carrier aircraft and sent a few Abyssal fighter squadrons to intercept.

But as it got closer, the sheer size of the ship blocked out the sky.

Even after years of fighting the Naval Base shipgirls, she had never seen anything this outrageous.

Boom boom boom—

She rotated her turrets and fired upward experimentally.

The shells exploded against an energy shield, bursting into fireballs that failed to even scratch the hull.

"You say she's the strongest battleship among the Abyssals?"

Richelieu asked.

"She could take on multiple of you at once?"

"Yes, don't let your guard down poi! Even Yuudachi's torpedoes couldn't hurt her poi..."

Yuudachi was just about to finish her warning—

Click—

The main cannon under the starship locked onto the Battleship Water Demon.

BOOM—

The super-graviton cannon and erosion missile struck the sea almost simultaneously, releasing a dark-red energy field that exploded across the surface, expanding into a hemisphere several kilometers wide.

With blinding light and deafening roar, the erosive energy spread outward, disintegrating everything into base particles.

The Battleship Water Demon didn't even have time to react—she and her rigging were completely annihilated.

The entire escort fleet followed, wiped out by the high-energy barrage.

When it was over, the sea was empty.

Not even a scrap of wreckage remained.

"Aba aba..."

The native shipgirls rubbed their eyes and pinched their cheeks.

They couldn't believe such powerful weapons even existed in the world.

"Next."

Richelieu's expression didn't change. She locked onto the next Abyssal fleet on radar.

"The Commander said two days, so it'll be two days."

"Phew—these Abyssals are way easier than the Sirens."

The Azur Lane shipgirls were quietly overjoyed.

They really did feel like max-level players returning to a beginner zone to casually farm mobs.

With complete dominance in technology and strength, the tactics Setsuna assigned to the Azur Lane and Arpeggio shipgirls were exceedingly simple.

The starships would lead the way, delivering concentrated strikes on Abyssal strongholds and major fleets.

Spot them, strike them, annihilate them.

The Angeloids followed behind the fleet to clean up any scattered remnants and stray Abyssals that might slip through.

Along the way—

The Azur Lane shipgirls devoured hotpot and sang songs, wiping out nearby Abyssals with unbelievable efficiency.

Against the interstellar fleet, the Abyssals had no chance to resist.

"Anchorage Demon! That's the Anchorage Demon!"

"Her armor's crazy tough—even Kongou's main cannons couldn't penetrate her!"

As they passed a certain sea region, Akatsuki, Hibiki, Ikazuchi, and Inazuma all chattered at Yukikaze, introducing her to one of the Naval Base's formidable enemies.

"Three months ago, we formed an expedition team and fought the Anchorage Demon for an entire day and night. We barely managed to eliminate the two Destroyer Princesses escorting her..."

"Even Kongou-class guns didn't leave a scratch on her."

Whoosh—

From Yukikaze's ship, dozens of erosion missiles streaked across the sky, erupting over the sea with a deafening explosion.

The Anchorage Demon and her escort fleet were instantly vaporized.

"No big deal nanoda!"

The beast-eared little shipgirl shook her head and proudly posed with her hands on her hips, showing off her new weapon.

The native Yukikaze and other destroyers looked on with envy.

They compared their own rigging-mounted 533mm and 610mm torpedoes, then looked again at Azur Yukikaze's erosion missiles.

They stared longingly at the beast-eared girl.

"This is a weapon the Commander personally designed for Lady Yukikaze nanoda! We had to fight several battles against the Arpeggio fleet to get it!"

"You can take a look, but don't touch! It's dangerous!"

Yukikaze removed a dark red erosion missile and handed it over like a precious treasure, then began bragging about her glorious adventures in the Arpeggio world.

The native destroyers listened in awe.

"A weapon designed by the Commander himself..."

The native shipgirls grew increasingly envious.

A Commander who could take them on expeditions across worlds, provide shelter and a home, and personally upgrade their equipment—it sounded like an impossible dream.

Nagato and Yamato were certainly responsible leaders, devoted to fighting the Abyssals and caring for their comrades.

But compared to the Azur Lane Commander, something vital was missing.

"If I let him be my Commander, would he upgrade my weapons too? Make my turret-kun even stronger?"

Amatsukaze suddenly asked.

Cough cough cough—

Yukikaze nearly choked.

"Probably, but isn't that a bit sudden?!"

...

In the carrier fleet—

"Carrier Demon, she's an elite-class Abyssal. Her Abyssal Revenge Fighters and Abyssal Hell Bombers are formidable! Be careful!"

On Enterprise's ship, Zuikaku and Hiyou pointed out the Abyssal Princess below.

That white-haired, red-eyed shipgirl, huddled inside her massive rigging, stared blankly at the giant warship in the sky.

Ka-ka-ka—

Enterprise opened her sealed hangar, unleashing over a hundred black-and-red space fighters.

They roared out with dizzying maneuvers, blanketing the area below with super-graviton cannons and erosion missiles.

The Abyssals' WWII-era anti-air couldn't even come close to stopping the space fighters.

They couldn't even lock on—only when they saw the overwhelming wave of aircraft with their own eyes did they realize what was happening.

The Abyssal fleet hurriedly launched their own aircraft in response.

But against such overwhelmingly advanced military technology, the aerial battle quickly devolved into a turkey shoot.

The once-feared Abyssal aircraft were blasted into fireballs one after another.

...

The carrier shipgirls quickly discovered that their opponent's aircraft were inferior across the board—in speed, durability, and firepower.

Fighting the Abyssals here was much easier than training battles back on Earth. Within just over ten minutes, the Carrier Water Demon and her entire escort fleet were blasted to dust by Enterprise.

"So this is how interstellar shipgirls fight? That's terrifying..."

The native shipgirls were thoroughly shaken.

The concept of annihilating enemies from miles away with overwhelming firepower was both cutting-edge and shocking.

"Some of the carrier shipgirls in the Naval Base used to say that in the future, wars would belong to carriers and their aircraft, and battleships would become obsolete."

"But now it seems... maybe not. Big-gun decisive battles still have their place."

Inside the Eternal Snowfall, Nagato from the KanColle world let her imagination run wild.

"...The concept of big-gun battleships in the interstellar age isn't the same as what you think."

Setsuna sighed.

"In wars that span astronomical distances, it's not just weapon strength and armor that matter—sensor capabilities and mobility are crucial too."

"After being refitted as starships, the lines between battleships and carriers blur. Battleships have aircraft, and carriers have main guns. The only difference is in scale."

"Oh..."

Nagato nodded thoughtfully.

She could sense that this man was extremely knowledgeable, well-versed in shipgirls, naval, and space warfare.

As the former acting commander of the Naval Base, she felt outmatched.

Even though Setsuna hadn't received any formal academy education, his experience—gained from countless battles and campaigns across different worlds—made him a battle-hardened veteran.

In just half a day, with the starships' carpet-bombing strikes, the sea around the Naval Base was completely cleared.

"Beyond this point is the core of Abyssal territory."

Yamato looked at the darkening sky and the increasingly dense Abyssal presence on the water, awe in her eyes.

"Even at the Naval Base's peak, we could barely get close to this region."

"Rumor has it the Abyssal leader is hiding here."

"Oh?"

Setsuna looked down.

The sea was dyed pitch-black, clouds loomed overhead, and it seemed the Abyssals had an innate ability to alter the environment.

Monstrous, twisted Abyssals prowled across the waves.

"The leader of the Abyssals? Hm... could it be Abyssal Yamato?"

He thought for a moment. According to the lore, Abyssals were the vengeful spirits of sunken ships—dark beings born from lingering hatred against humanity.

Judging by the features of Battleship Water Demon and Carrier Demons, it was clear they resembled their shipgirl counterparts.

So if the flagship of the Naval Base was Yamato, then it made sense for the Abyssal leader to be an Abyssal Yamato.

"Doesn't really matter. Even if it's Space Battleship Yamato, she's getting smacked."

Whoosh—

The Eternal Snowfall ignored the lesser grunts and fired up its engines, cranking its sensors to full power as it began sweeping the sea for their real target.

Once inside the Abyssal-controlled zone, native shipgirls found their communications disrupted—but that didn't affect the starships.

Not long after—

Bzzz—Bzzz—

The ship's onboard AI suddenly sounded the alarm.

[Alert! Target detected at 32.76 kilometers northwest!]

[Alert! Target confirmed!]

"Wah?!"

Yamato, Nagato, and the other native shipgirls jumped at the sudden alarm.

"Is it a powerful enemy?!"

They instinctively manifested their rigging and assumed combat stances.

"Hm?"

Setsuna steered the ship toward the source.

There, standing on the sea, was a small white-haired, red-eyed girl in a white dress.

Her skin was pale, her expression emotionless, and several black-and-red turrets floated behind her—clearly her rigging.

Compared to elite Abyssals like Anchorage Demon or Carrier Water Demon, she was much smaller and lacked that usual vicious aura.

In fact, she looked kind of cute—adorably fierce, even.

Surrounded by a large escort fleet of Abyssal ships, this little Abyssal was clearly their commander.

"Is that... Destroyer Princess? No, Light Cruiser Princess? Doesn't seem right..."

The native shipgirls who knew the Abyssals well tried to guess her identity.

"Wait, is that Fortress Princess?!"

Judging by her rigging and aura, there was no doubt. She was, in a sense, a relative of the shipgirls—

Shipgirls were personifications of warships. Fortress Princesses were the personification of naval bases.

Their power far exceeded that of regular shipgirls, though their mobility was poor.

Whoosh—

Upon seeing the Eternal Snowfall, Northern Princess raised her hand, launching over a hundred pitch-black Abyssal aircraft from her rigging.

They swarmed toward the starship.

"Hand over the Zeros and Ryuuseis... now...!"

...

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