Crossover Shipgirls: Building a Dimensional Empire from Scratch

A few days later, in the morning.

At the Naval Base plaza.

On a marble-decorated column hung a large, eye-catching banner:

[Naval Base Admiral Appointment Ceremony]

Azure, Arpeggio, and Kancolle shipgirls chirped among themselves, gathering under the stage and whispering.

Welcoming a new commander—according to the native shipgirls, he should be called an admiral—was a rather novel experience for them.

Although they had briefly fought together, most of the time had been spent aboard the starship, watching the Eternal Snowfall swat away the Abyssal Fleet like a match-3 game.

The native shipgirls only knew that Setsuna and the Azure shipgirls were incredibly powerful, with highly advanced technology. They knew little else.

Most of them accepted Setsuna's position as admiral out of gratitude and respect for their supreme flagship Yamato, but many hadn't even spoken to him.

As such, the native shipgirls mostly crowded around the Azure shipgirls, trying to find out what kind of person the Commander really was.

"The admiral seems really gentle, doesn't he? He must really care for his companions, right?"

Native Shoukaku asked Richelieu.

"Gentle? Pfft—"

Richelieu nearly burst out laughing.

"He's gentle with shipgirls most of the time, sure, but don't mistake the Commander for a nice guy."

"If you want a comparison, I'd say he's kind of like Bismarck... no, actually, his methods are even more direct."

"Eh? That military-like shipgirl?"

Shoukaku was a little surprised.

Setsuna always seemed easygoing in the Naval Base—it was hard to associate him with someone as forceful as Bismarck.

"He's very tolerant with shipgirls. Even a bit of insubordination doesn't bother him. But when it comes to enemies or outsiders—heh, you'll understand eventually."

Chen Hai crossed her arms, speaking as a senior to educate Shoukaku.

She described the state of the Starsea Empire and recounted a few of their fleet's expeditions.

Upon hearing that the Eternal Snowfall could mercilessly destroy entire noncompliant countries or worlds, the native shipgirls were stunned speechless.

That was the mark of a true battle-hardened soldier.

Someone who could, without hesitation, order the annihilation of a nation or world, using power to make other worlds kneel.

"I used to think the admiral just needed to be handsome and responsible, but to think he's also the ruler of a super empire?!"

Nagato realized that to Setsuna, the Naval Base was just a tiny corner of a world.

She felt overwhelmed by the honor—being able to invite someone of that caliber to serve as admiral was a blessing the shipgirls must've earned over many boilers' worth of smoke.

"Does the admiral have someone he likes, poi?"

Yuudachi poked her head out with a curious look.

Gossip always catches interest, and the other native shipgirls perked up immediately.

"Only the most outstanding can stand beside the Commander~~"

Taihou answered with her signature yandere pride, proudly explaining her relationship with the Commander.

Hearing about this bizarre thing called "oath-bound shipgirls," the Naval Base shipgirls couldn't stay calm.

"To entrust everything to each other, to live and die as one with the admiral... so romantic!!!"

"We didn't even know about this?!"

The younger shipgirls were amazed by this oath-like bond.

The First and Fifth Carrier Divisions exchanged glances—fire clearly ignited in their eyes.

"?"

The Azure shipgirls suddenly sensed a whole new wave of future rivals.

Spirits and Heroic Spirits were few, but this was hundreds of shipgirls identical to themselves!

"If the Commander has that many companions, does he even have enough time?"

Nagato asked, slightly puzzled.

"Of course he does. That's one of the Eternal Snowfall's wonders..."

Taihou was just about to explain some rather indecent knowledge to the naive native girls when—

Vmmm—

With the crisp sound of a horn,

Setsuna and Yamato stepped out from the main building, both dressed in formal uniforms and holding several documents, followed by several accompanying shipgirls.

The shipgirls quickly made way for them.

Once they stood on the platform—

"Then, the Admiral Appointment Ceremony shall now begin."

At Nagato's command, the shipgirls of the Naval Base stood in neat formation.

Grouped by class—destroyers, cruisers, battleships—they formed several phalanxes.

Their expressions were solemn and serious. Even the youngest shipgirls had put away their playful moods.

Acknowledging a new admiral was a sacred event for them.

Just as the Azure shipgirls had acknowledged their Commander, Setsuna had also spent time earning the trust of each fleet.

The band on both sides began playing a military march.

"The great wind rises, the clouds surge high—how can we not have shipgirls guarding the four seas..."

One of the Azure shipgirls mumbled along, prompting surprised glances from those nearby.

Step, step.

Yamato stepped forward and, with a formal tone, declared the most important decision in the Naval Base's history:

"I, Yamato-class battleship No.1, Supreme Flagship of the Naval Base, hereby swear."

"From this day forth, Lord Setsuna shall be the first—and only—Admiral of the Naval Base. I, on behalf of all shipgirls, accept your command."

"We hope you will lead us to victory and witness an even grander world."

Yamato bowed deeply and handed Setsuna the seal, documents, and other items symbolizing the Supreme Flagship's authority.

Her etiquette was impeccable—even the normally relaxed Azure shipgirls felt ashamed in comparison.

"I will do everything in my power to protect you, offer you the best, and build a prosperous empire together."

Setsuna accepted the items and replied sincerely.

"From now on, we are in your hands."

Yamato lowered her head again and bowed, raising a beautifully decorated, brand-new command sword above her head.

It had been forged long ago in case an admiral was ever appointed—until now, it had never been used.

Today, it finally found its rightful owner.

"Mm."

Setsuna accepted it.

Clack—he drew the blade, gave it a flourish, lightly touched it, then sheathed it again.

"I swear, in the name of myself and the Starsea Empire, to protect you until the end of time."

Boom boom boom—

Ceremonial cannons fired, and flags fluttered.

The Naval Base erupted in celebration.

"Waa—"

The native shipgirls broke into cheers, many hugging each other in excitement.

For the first time, they felt a true sense of belonging.

From this moment on, they were part of the Starsea Empire.

Through joy and sorrow, there would be someone to share and shoulder the burden with them.

Their Admiral would lead them beyond the seas, into space, and into the unknown multiverse.

"Welcome to the Starsea Empire family."

Setsuna looked at the jubilant Naval Base shipgirls and smiled, nodding.

He felt the heavy weight of their trust.

More importantly, he had taken another step toward that great goal.

"I will become the Commander of all worlds, the Commander of all shipgirls."

"Ah, the number of potential wives just increased again."

...

After the Naval Base's highest authority transfer ceremony, Setsuna officially took office as Admiral.

He now sat in the main building's grand office.

This room had once belonged to Yamato. It was designed in traditional Japanese style—elegant and tranquil.

Now Yamato stood beside him, taking the initiative to serve as his assistant.

Setsuna flipped through the documents.

All were in paper format—filling several cabinets. Yamato worked meticulously.

She had recorded resource consumption, personnel changes, and combat situations with the Abyssal Fleet in perfect detail.

This old-fashioned office method was a poor fit for Setsuna, who was used to working with holographic interfaces.

Back then, a few taps on the screen could bring up any data he needed. Now, people had to dig through stacks of files manually.

"Hmm... This naval base has fewer shipgirls than Azure Fleet, though there are many with identical names."

Setsuna skimmed the roster—about 300 shipgirls served at the Naval Base.

There were no blueprint ships or META shipgirls here—only warships that had historically existed during WWII. Not as many as in the port district.

Still, it was a fairly strong elite force.

"In the early days of the Naval Base, we briefly worked with the human government to resist the Abyssal Fleet."

"But as the Abyssal territory grew and sea routes were cut off, humans became overwhelmed, and the Naval Base was completely isolated."

Yamato handed Setsuna a few records.

Most were communication logs between both sides—notifications about enemy movements or sightings of new Abyssal Fleets.

"That doesn't matter. The humans of this world will soon have a new order."

Setsuna flipped through them with little interest.

To this world's humans, shipgirls were like urban legends.

They only knew that strange sea monsters appeared on the ocean—and that a group of girls in miniature rigging fought them by walking on waves.

As for the details, they knew nothing. Just fending off the Abyssal Fleet left nations in chaos.

After reading for a while, Setsuna gained a good grasp of the Naval Base's condition.

He began forming a rough development plan.

Leaning back in his chair, he looked at Yamato, Nagato, and the other native shipgirls.

"Do you all have anything you want to do from now on? You can tell me."

"Umm..."

Yamato thought for a moment.

"Admiral, the Naval Base was created to fight the Abyssal Fleet. Now that the Abyssals are gone, it feels like... we have nothing left to do..."

She and Nagato looked a little downcast.

Like weapons of war that had completed their mission.

—And the mission had been completed by someone else.

"How could that be? You'll have plenty to do."

Setsuna nearly laughed.

He opened several holographic interfaces with his rigging.

"First, you will all undergo starship-class transformation and become the fourth shipgirl fleet—alongside Azure, Siren, and Arpeggio Fleets."

"Second, this Naval Base will be heavily upgraded. I'm going to make it the administrative capital of this world, to manage the Kantai Collection world."

"Third, the Starsea Empire will soon launch a new expedition. We're heading into space—to fight aliens. Yep."

"???"

Just three sentences left the native shipgirls nearly speechless.

"Turn us into starships, and expand the base?!"

Yamato, calming herself, immediately began flipping through documents to help Setsuna tally the numbers.

"Admiral, due to years of war, the Naval Base's resources are quite limited. Large-scale renovations might not be feasible..."

"These are our steel and aluminum reserves. Also, we don't have many construction workers. We used to build everything together ourselves..."

She spoke earnestly, while Setsuna found himself increasingly amused.

Native shipgirls truly lived up to the name—apparently, back when the base was being built, they had to personally mix cement and lay bricks.

Compared to the luxurious and pampered Azure shipgirls, they gave off a refreshingly down-to-earth feeling.

Setsuna patted Yamato on the shoulder.

"Don't worry, we'll bring you up to the space age in no time."

"Eh?"

...

Outside, in the plaza.

Setsuna took out a teleportation anchor and set it in front of the Naval Base's main building.

Vmmm—

The dark blue anchor slowly levitated into the air, locking onto this world.

[Primary Node Teleportation Network Established]

[Node #15: Fleet Collection]

"The 15th world already, huh..."

He sighed and contacted Yat Sen in the capital.

"Send 6,000 Purple Bulins and 1,000 Gold Bulins. Bring construction materials—I'm renovating the Naval Base."

"Understood."

Half an hour later—

Swish—

Gold and Purple Bulins carrying wrenches and drills marched out of the teleport anchor in formation.

"Burin!"

"Commander, Bulin Construction Squad #75 reporting for duty, burin!"

"Whatever the mission, leave it to Bulin! Buli!!!"

The leading Gold Bulin saluted Setsuna.

"???"

The synchronized movements of the Bulins left the native shipgirls speechless.

"Admiral, are they shipgirls too?"

"Why do they all look exactly the same?!"

Yamato stared in shock at the crowd of little cuties.

The Bulins packed the entire plaza—same hairstyle, same outfits, same wrenches.

Like a clone army.

"Bulins and lolis are the foundation of the Starsea Empire."

Setsuna imparted this simple truth to Yamato.

Then, he assigned tasks to the Gold Bulins.

"Rebuild the Naval Base according to the Azure port district's structure."

"Bulin understands!"

The Bulins immediately dispersed.

They were so familiar with Azure port layouts they didn't even need blueprints—they could build them with their eyes closed.

From their rigging, the Bulins pulled out piles of pre-packed building materials.

With wrenches and drills clinking away, they got to work.

At a pace visible to the naked eye, the Naval Base buildings were swiftly demolished, and new starship-class facilities were constructed in their place.

The native shipgirls watched the entire process slack-jawed.

"Ehhh?! Your tools are just wrenches and drills?!"

"Dumb little sister also has a hammer, burin! But we don't need it here~ She uses it for building starbases and spaceships."

"How did you dismantle the dock that fast?!"

"Like this, then that, then done—burin!!!"

"Can I watch how you build houses?"

"Sure, but even if you watch, you won't understand—burin~~"

The bewildered native shipgirls tried earnestly to learn a few techniques from the Bulins.

Only to discover that their powers came from the mysterious force known as Joyful Bulin Logic—which had absolutely nothing to do with science or engineering.

Eventually, they gave up and resigned themselves to being spectators.

"Oh right, I've also brought some textbooks and new weapons. Take a look."

Setsuna pulled out several thick stacks of textbooks.

They covered interstellar combat—compiled by the Imperial Starship Academy.

The shipgirls didn't need formal classes, but it was still important to familiarize themselves with space-era gear.

Otherwise, after their body upgrades, they wouldn't even know how to use their own equipment.

"Ababa..."

Yamato flipped through the books—pages full of astrophysics, quantum mechanics, and other high-level content.

She recognized every word, but couldn't understand any of the sentences.

It felt like she was a native being enlightened by a suzerain.

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