Crossover Shipgirls: Building a Dimensional Empire from Scratch

At the unanimous request of the Sakura Empire fleet, Setsuna decided to bring most of the Sakura Empire shipgirls to the Blue World so they could meet their counterparts from another universe.

The fleet spent some time resting and preparing at the base.

On one hand, the shipgirls were studying the Fleet of Fog, as understanding their opponent was crucial. Although the Fleet of Fog also consisted of shipgirls, they lacked the ability to manifest and project ship rigging like the Azur Lane shipgirls. Their hulls could not be retracted.

With high offense and thick defenses, they were formidable adversaries in naval combat. The Super-Graviton Cannon and Klein Field were particularly difficult to deal with.

However, the Azur Lane shipgirls had already undergone starship modifications. If necessary, they could engage in orbital strikes against the Fleet of Fog.

On the other hand, Setsuna was waiting for the cooldown on his portal-opening ability. He had recently sent Shinano and the others to the Nekopara world and had also unlocked several new worlds on the star map. He needed time to recover.

”Strange, why is Shinano taking so long?”

”Is Nekopara really that difficult to handle?!”

One day, Setsuna suddenly realized that Shinano had been gone for quite a while and activated the communication link with the expedition fleet.

”Commander? Hello, hello?!”

On the screen appeared a silver-haired shipgirl with a slightly manic expression—Hakuryuu.

”You all have been there for almost a month. Why haven’t you returned yet? We’re about to set out for a new world.”

”Did you encounter any difficulties? Do we need to adjust the spiritron transfer schedule, or should we send a support fleet?”

Richelieu frowned, deep in thought. She couldn’t imagine anything in the Nekopara world being able to stop a dozen starship-tier shipgirls.

Even if all the human military forces in that world combined, they wouldn’t stand a chance.

”Uh… we’ve already found the catgirls you requested and acquired the technology for their modifications.”

Hakuryuu waved a stack of documents in her hand.

She then lifted a large cardboard box filled with familiar little catgirls.

There was Chocola, the brown-haired, red-eyed twin-tailed catgirl, Vanilla with her silver hair and blue eyes, along with Azuki, Coconut, and other various breeds.

Since the fleet had arrived early, these catgirls were still young, curled up together in their sleep, their tails swaying occasionally.

”Oh… these catgirls are quite adorable… Maybe we should keep some in the capital…”

Sister Richelieu subconsciously reached out to touch the screen, as if trying to pet the catgirls.

Then she suddenly paused:

”Wait, if the mission is already complete, why haven’t you returned?”

”We’re conquering the world!”

Hakuryuu declared confidently.

She turned the camera outside—to Mount Rushmore in South Dakota.

Setsuna recognized their location immediately.

A vast swarm of carrier-based aircraft carpet-bombed the forces below.

Energy weapons streaked across the sky, reducing tanks and armored vehicles to molecules.

To the humans of that world, it was nothing short of an alien invasion.

”We figured since we were already here, just bringing back a few catgirls seemed boring. So, we decided to make this world our vassal instead…”

”At first, it went smoothly, but the people here weren’t happy about it. They started shouting things about ’freedom’ and ’democracy’ before charging at us. Tch, I don’t really get it.”

”Maybe they just don’t like having a new boss.”

As she spoke, Hakuryuu fired the ship’s cannons, effortlessly taking down a squadron of fighter jets.

”Ha?!”

”Alright then…”

Setsuna and Richelieu both facepalmed.

This was unexpected, yet completely within reason.

There were indeed plans to send fleets to conquer other ordinary worlds, but Hakuryuu had moved a little too fast.

”Remember, we’re not here to loot and destroy—we need sustainable development.”

Setsuna reminded her.

”Understood, you mean… sustainable resource extraction, right?!...”

Hakuryuu scratched her head.

”Just like in Demon Slayer, first use force to establish prestige, then introduce advanced technology to improve the lives of the common people, exploit the upper class and capitalists, and balance the world’s power structure.”

”That way, they’ll even thank us, won’t they?”

”That’s the idea.”

Setsuna found Hakuryuu quite sharp—rough but perceptive.

He had no intention of plundering other worlds like a pirate. Interstellar civilizations had much more refined methods.

Mutual prosperity and shared development—so long as they acknowledged the Alliance’s suzerainty, pre-space civilizations could reap endless benefits from advanced space-age technology.

For example, controlled nuclear fusion, considered obsolete in the Azur Lane world due to Cube Energy, would be an invaluable treasure for ordinary Earth civilizations.

Mass-produced genetic medicine capable of curing various terminal illnesses was another benefit that bio-labs could offer.

With both energy and medical advancements, ordinary people would likely cheer, shouting, ”Hail the aliens! I want to be a shipgirl’s pet!”

As for nations and corporations that relied on financial exploitation… their end had come.

Setsuna needed vassals focused on production, not financial games that yielded no tangible value.

”Please rest assured, Commander. Although this operation was somewhat rushed, I will handle the remaining work properly.”

The silver-haired, fox-eared Shinano approached, bowing her head respectfully.

”By the time we return, everything here will be in order.”

”Alright, I’ll leave it to you.”

Setsuna agreed.

...

After a period of preparation...

North of the capital, at Golden Horn Bay.

Setsuna selected the members of the expedition fleet.

Most of the Sakura Empire shipgirls, along with Richelieu and Belfast as sworn escort ships, plus Observer and Purifier, the two Siren girls.

The Spirit of Origin and the ever-curious Gudako also stood beside him.

The shipgirls were excited about exploring the Blue World, but the Heroic Spirits and others were less interested in meeting a new set of shipgirls.

As for Mio, Setsuna believed she could handle many unexpected situations.

If all else failed, she could simply open Ain Soph. In her domain, she was essentially a god.

”Alright, prepare to depart.”

Shua—

Setsuna first opened the communications interface.

[Arpeggio of Blue Steel (Pre-Space Age)]

A world set in a near-future Earth, with a technological level slightly above the early 21st century.

No supernatural abilities exist, but the advanced Fleet of Fog dominates the seas.

Comparison of Strengths:

• Technological Level: Slightly Inferior.

• Military Strength: Like a Ant.

• Economic Power: Like a God.

”Huh?”

Setsuna noticed that although the other side was just a terrestrial civilization incapable of spaceflight, their technological level was only slightly inferior.

It seemed the Fleet of Fog’s technology was truly ridiculous.

He clicked on the communication interface, wondering if there was anyone worth negotiating with…

Bzzt—

After a flicker on the screen…

A girl appeared. She wore a gray sleeveless shirt with a blue tie, black thigh-high stockings, and short boots.

Her silver-white hair cascaded behind her, her skin as pale as snow, and her eyes remained closed.

The girl stood at the bow of the ship, behind her a towering black command tower and two triple-mounted 460mm gun turrets at the front of the deck.

Although she appeared to be a loli, like Nagato, she was a true big-gun battleship.

”Musashi?”

Setsuna was a little surprised. He hadn’t expected to connect directly with the Supreme Flagship of the Fleet of Fog’s Guardian Fleet.

”Hm?”

Sensing the sudden activation of a holographic interface, Musashi opened her eyes, revealing crimson pupils. She gazed in confusion at Setsuna and the shipgirls behind him.

”Who are you...?”

”We’re shipgirls from another world, coming to take a look.”

He greeted Musashi briefly.

”Which fleet do you belong to?”

Musashi’s gaze swept across the other shipgirls. At this moment, everyone had manifested their hulls, preparing for departure.

Her instincts told her these girls shared a certain resemblance to herself.

”Wow, your hull is huge, it looks so futuristic.”

”Oh, this main cannon is identical to our Musashi’s...”

The shipgirls gathered around, curiously examining Musashi’s vessel.

Its dark exterior was etched with golden patterns, exuding both science fiction aesthetics and an imposing presence.

There were also many weapons they didn’t recognize.

Most astonishingly, despite being a battleship, Musashi was equipped with torpedo launchers and missile silos—features completely unexpected on such a vessel.

Many of them clicked their tongues in amazement.

”...”

Musashi remained silent for a moment, looking at the lively shipgirls surrounding Setsuna.

”Why have you chosen to align yourselves with humans?”

”Huh?”

The shipgirls, who had been admiring her hull, froze.

”What do you mean?”

Nagato tilted her head.

”I have given a command to the entire Fleet of Fog—to expel all humans from the seas forever.”

”Why do you remain by his side?”

Musashi’s eyes sharpened.

”He is our Commander!”

Yukikaze retorted angrily.

”Commander? Why would you even need something like that?”

Musashi frowned in confusion.

”Hah?”

The shipgirls stirred in agitation, some itching to teach her a lesson.

”...”

”It seems she has mistaken us for being part of the Fleet of Fog—one of her subordinates.”

Richelieu realized.

Since members of the Fleet of Fog could communicate through their Mental Models, it was easy to see how this misunderstanding had arisen.

”What an unpleasant little brat.”

Azur Lane’s Musashi furrowed her brows as she looked at her Fog counterpart.

”...”

”Forget it.”

Setsuna chuckled, waved his hand, and closed the communication.

”No need to argue with a child. Besides, isn’t it fun to discipline an unruly loli?”

”Exactly, sooner or later, she’ll come to understand the size and strength of our Commander.”

Gudako nodded sagely.

Bang!

”Why did you hit me?!”

”I’ll say it again—I prefer them big.”

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