Crossover Shipgirls: Building a Dimensional Empire from Scratch

Two days later.

Outside Yokosuka Harbor.

Purifier, Observer, Iona, and several Sakura Empire submarines towed a massive warship wreck into the harbor.

Its entire body was silver-white, with golden engravings etched along the hull.

Although it had been submerged at the ocean’s depths for a long time, there was not a trace of rust on it.

However, the ship was severely damaged—its keel was nearly split into four sections, and half of its bridge had been forcibly sheared off.

On the deck and along its sides were several holes exceeding ten meters in diameter—marks left from its battle with Musashi.

”So this is… Arpeggio’s Yamato?”

The shipgirls examined it from top to bottom.

The size of this Yamato far surpassed that of the historical ”ultimate battleship.” Even by starship standards, it was not small.

”Phew—”

”We found her at the bottom of the Pacific Ocean. It took quite some effort.”

Purifier climbed out of the water, jumped ashore, shook off her wet hair, and wrung out her soaked sailor uniform.

”She’s much heavier than I imagined. Tsk, she feels almost like a Yamato-class starship.”

”Oh?”

Musashi crossed her arms and scrutinized this Yamato-class ship from another world.

The iconic three triple-mounted 460mm main guns remained unchanged, but on her armored sides were more than a dozen supergravity cannons.

They resembled the sails of a warship.

Normally, these weapons remained concealed within the armor. Upon engaging an enemy, they would transform and deploy, delivering devastating blows.

The Bulins swarmed forward.

Using various devices in their hands, they began inspecting Yamato.

Takao’s ship body was also docked beside Yamato’s. Though her injuries were not severe, she still required repairs.

”Hey? Who brings a hammer to repair a warship?”

”Are you sure you guys know what you’re doing?”

Takao eyed the hammer-wielding Bulin with apprehension.

”Don’t question the magic of the Bulins. This is a Specialized Bulin. They can build wonders and legitimate space-faring vessels—fixing a few ships is nothing.”

Setsuna signaled Takao to stay calm.

”The power system is destroyed, the midsection of the hull is damaged, and there are several breaches on the deck. We estimate it will take some time to repair, buri.”

Bang—bang—bang—

The colorful Bulin began hammering away at the hull.

Takao had no idea how the Bulin managed to repair warships with just a hammer, much like how Setsuna couldn’t comprehend how they built the capital ship from just a wrench and sheer willpower.

However, as chaotic as the process seemed, the results were always correct.

”...”

An hour later.

A strange sensation coursed through Takao’s body—her hull had indeed been repaired, and the discomfort from her previous damage quickly faded away.

”You guys...”

”Forget it. I’ll never understand your methods…”

She gave up trying to comprehend something outside her expertise.

Before long, a colorful Bulin arrived with a report.

”Commander, the damage to Yamato is quite severe. We need a large amount of nanomaterials to repair her…”

”Additionally, her weapon modules are also damaged. Approximately 70% of the hull requires refurbishing, which will take about 5 to 7 days, buri.”

This was essentially equivalent to building a brand-new ship, but Setsuna was unconcerned about the resource consumption.

”Can you manufacture Super-Graviton Cannons, Corrosive Warhead Torpedoes, and Corrosive Warhead Missiles?” Setsuna asked.

”Bulin thinks Bulin can do it!! We can take some samples back to Akashi for reverse engineering, and then we’ll be able to produce them, buri!”

The colorful Bulin bounced excitedly as she answered.

”Alright.”

If the Bulins believed they could figure it out, then they would surely find a way to produce it.

Setsuna had Takao dismantle several corrosion torpedoes and missiles, and also handed over the vibration warheads acquired from the transport ship to the Bulins, instructing them to take everything back to the repair team.

Even without blueprints, given the shipgirls’ advanced technological capabilities, as long as they had samples, they could find a way to replicate them.

...

While the Bulins were repairing Yamato, Setsuna dispatched Purifier, Observer, and some Sakura Empire shipgirls to begin their conquest of this world.

The first target, of course, was the island nation they were currently in.

Due to rising sea levels, Tokyo had become a scattered capital, resembling a collection of floating islands.

Inside the Tokyo Parliament Hall, the stationed commander of Yokosuka vividly described what he had witnessed to the Prime Minister and the gathered parliament members.

”Spaceships!! Actual spaceships!”

”And invulnerable mutant warriors who can withstand direct tank cannon fire! They were bombarding people from the shore with ship cannons!!!”

The admiral was visibly agitated.

The parliament members and the Prime Minister were utterly bewildered.

”Are you saying that the Fleet of Fog has landed?”

”That can’t be right. Over the past few decades, there has never been a recorded instance of the Fleet of Fog launching a land assault. They rarely even approach coastal areas…”

The Prime Minister stroked his chin in thought.

”Not the Fleet of Fog! Aliens!!!”

The admiral was exhausted, painstakingly explaining just how terrifying the fleet they encountered was.

...

”Aliens? Did you not sleep well last night? Or are you hallucinating?”

Just as chaos engulfed the parliament hall—

Buzz—

A deep, resonant hum echoed from above as a fleet of starships, blotting out the sky, appeared over the city.

A large number of Siren Executors were airdropped, swiftly eliminating resistance and surrounding the entire city, including the parliament hall.

Observer, seated on her octopus-like ship rigging, gracefully descended before the assembled officials.

”I believe someone has already briefed you on the situation. Now, will you surrender?”

The little girl puffed out her cheeks and spoke casually:

”But don’t worry, we’re not some kind of man-eating aliens, nor do we intend to commit genocide—provided you know your place.”

”From now on, behave as a tributary state, and we’ll even provide you with some advanced technology. Hmm, this place seems quite suitable for marine industry development.”

”???”

The high-ranking officials stood frozen, unable to react.

Only the personnel from Yokosuka shrugged.

”See? What did I tell you? Aliens, right? I wasn’t lying, was I?!”

”Hey, are you going to give us an answer or not? My time is valuable, and I’m not here to waste it on you locals.”

Observer knocked on her ship rigging impatiently.

”I’ll give you 20 minutes to decide.”

”20 minutes?! You expect us to decide the fate of our entire country in just 20 minutes?!”

The parliament hall erupted in panic.

Some of the more timid individuals, upon seeing the overwhelming number of Siren Executors and the starships looming above, began crying out of fear.

”Crying? That still counts toward your time.”

The little girl pulled out a clock and gave it a tap.

”If the time runs out and I still don’t have an answer, I’ll order the attack.”

...

10 minutes later.

Satisfied, Observer boarded a starship, holding a signed surrender agreement.

The agreement had been drafted long ago, meticulously detailing the obligations and responsibilities of a tributary state. All they had to do was sign.

She opened the world map in the control room.

”Done.”

”Let’s see... the next target is... tsk, Eagle Fortress.”

”Hopefully, they don’t get any strange ideas... Let’s settle this within 30 minutes. Move out!”

...

In the depths of the ocean.

Far from any land, deep in the open sea.

Musashi was leading the Fleet of Fog, patrolling the waters.

The escort fleet of the Fleet of Fog’s flagship was massive, numbering in the thousands when counting the mass-produced vessels.

Accompanying her at a moderate distance were elite battleships such as Kirishima, Haruna, Hiei, and Kongou.

Unlike the pacifist Yamato, Musashi had only one goal: to drive humanity completely out of the ocean.

As such, any human fleet daring to venture into the seas would be mercilessly destroyed.

Some within the Fleet of Fog considered her stance extreme, but Musashi didn’t care.

However, she had recently noticed something strange—human fleets had stopped even making exploratory forays into the ocean.

”What’s going on? Are they too afraid to set sail?”

Musashi found it odd and contacted Takao and the Far East Fleet to gather information on the humans.

Then, she received a shocking report:

”What?!”

”That alien is conquering the world? He’s already taken over nearly half the nations? Unbelievable!”

”The entire world has been turned into his vassal states?!”

Musashi stood in stunned silence, unable to process the news for a moment.

”Aren’t you all being a bit extreme?”

”I just wanted to push humanity off the seas!”

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