Crossover Shipgirls: Building a Dimensional Empire from Scratch

Late at night, the naval base was quiet.

Moonlight poured through the windows, spilling into a modest bedroom.

Shoukaku, like a newlywed bride, sat at the vanity carefully tending to herself.

Shipgirls were naturally beautiful—stunning even without makeup.

Dressed in a red-and-white kimono, she looked even more graceful and elegant.

"Admiral, please take care of me from now on."

Shoukaku gently leaned into Setsuna's embrace, bringing with her a soft and delicate warmth.

Her silver-white hair brushed his cheek—it tickled slightly.

This was the essence of "wife material."

Setsuna couldn't help but sigh.

In terms of figure, Shoukaku wasn't the best among shipgirls.

Her usual kyudo outfit and short skirt were easy on the eyes, but fell short of being seductive.

It was her gentle, considerate nature—always thinking of the Commander—that made her the ultimate wife.

Who wouldn't love a beautiful girl who saw only you and was utterly devoted?

Setsuna held Shoukaku with one arm and gently stroked her smooth, long hair.

"Mm..."

Shoukaku lifted her head, sensing something different.

"Commander, Shoukaku is now yours."

"Please... be gentle."

She spoke softly, with a hint of shyness and hesitation.

"Mm."

Setsuna thought to himself that he was already a battle-hardened veteran.

But now wasn't the time to say that.

Instead, he answered with action, guiding and reassuring Shoukaku.

Toward this gentle and lovely wife, it was impossible not to feel protective.

"Admiral, does this mean I'm now your oath-bound shipgirl?"

"To live and die together, never to be parted?"

Amid the storm, Shoukaku's voice sounded a bit strained.

She truly wanted to confirm his feelings.

"Of course. From now on, you're my wife in every sense."

...

The next day.

When sunlight hit his eyes, Setsuna slowly opened them.

Shoukaku was still nestled in his arms, sound asleep.

Her long hair was scattered behind her, and her peaceful sleeping face—along with glimpses of soft white skin—was mesmerizing.

With native shipgirls, Setsuna usually held back a bit.

Their physical strength couldn't compare to starships.

They got tired, they got sore.

"Mm..."

He thought for a moment, then leaned back against the bed and brought up a holographic interface.

After a while—

"Hm?"

Shoukaku sleepily opened her eyes and saw Setsuna operating the interface.

"Admiral, what are you doing...?"

"Designing a new rigging for you."

Setsuna replied.

"We'll be returning soon, and you'll undergo full starship retrofit. I'm designing your new hull in advance."

Though every rigging design would eventually pass through his hands, he paid special attention to his oath-bound shipgirls.

He would add unique design elements just for them.

"Oh..."

Shoukaku's eyes sparkled with admiration.

No shipgirl could resist having her rigging personally designed by her Admiral! In every sense, it was a supremely romantic gesture.

"What type do you want? Carrier-specialized, or should I give you more main guns?"

Setsuna smiled and patted Shoukaku's head.

"In space, there's not much difference between battleships and carriers. You can equip axial weapons too, so don't worry about close-quarters combat."

"Hmm..."

Shoukaku leaned into his chest, carefully considering.

"Whatever the Admiral needs, just modify my rigging accordingly."

"No need for that—just choose what you like."

Setsuna pinched her cheek.

The two began picking together.

"A white rigging! Hmm, and it'd be best to differentiate me from the Shoukaku at Azure Lane Port—if people keep mixing us up, it'll be very confusing for everyone..."

"Also, for the interior design, um, I want to try a new style..."

Setsuna patiently explained the function of each module to Shoukaku, letting her choose the upgrade path she wanted.

After about an hour or two, they finally finished the selection and sent the materials to Bulin, asking the Starbase to prepare in advance.

"Hm?"

Just as they were about to get out of bed, Shoukaku noticed something odd.

"Commander, last night, didn't you...? You..."

"That's the effect of two Wisdom Cubes."

Setsuna shrugged.

To accommodate Shoukaku, he'd held himself back.

"Ah... then I guess I let you down..."

Shoukaku thought for a moment and decided this wasn't acceptable.

With a swish, she slid down out of view.

Not long after—

Knock knock knock—

Someone knocked on the door.

"Shoukaku-nee?"

"Why didn't you come for breakfast today? Are you not feeling well? Or is something up...?"

"We're supposed to keep practicing how to operate space-based carrier aircraft..."

A girl with dark green twin-tails pushed open the door.

Zuikaku, Shoukaku's sister in the Fifth Carrier Division, was usually inseparable from her. They each had keys to the other's room.

As soon as Zuikaku entered, she spotted Setsuna—and the suspiciously puffed-up blanket.

"A-Admiral? You're here too?"

"Have you seen my sister? Akagi is looking for her too."

Zuikaku stood there frozen, confused.

She sniffed the air—there was an unfamiliar scent lingering in the room.

"Um... uh..."

"Ahem. I'm here. Don't worry..."

Shoukaku poked her head out, her voice a little hoarse.

"Sister, you—?!"

Zuikaku instantly understood the situation.

She had long known Shoukaku had feelings for the Admiral, but she hadn't expected them to progress so quickly.

Smiling awkwardly, she realized she might have barged in a bit rudely.

She quickly raised the bag in her hands to cover the awkward moment:

"Sis, do you want breakfast? I just bought some."

"Those Dragon Empery shipgirls' cooking is really tasty!"

The plastic bag held soy milk and fried dough sticks, and the savory aroma was unmistakable.

They were clearly made by Ning Hai, Ping Hai, or perhaps Ying Swei and Chao Ho.

"..."

Shoukaku swallowed a little uneasily, eyeing the breakfast Zuikaku brought.

She'd never had soy milk before. On any other day, she might have tried it.

But today... better not.

"I'll take it."

Setsuna got up and took the bag from her.

Shoukaku was unexpectedly bold sometimes—willing to try things no one had dared attempt before.

And she hadn't wasted a single drop.

If he were an emperor in ancient times, Setsuna thought, he'd surely summon Shoukaku every single night.

"..."

Shoukaku looked a little resentful.

"Admiral, sometimes... you really do bully your shipgirls, don't you?"

"Right? You definitely do, don't you?!"

...

Two weeks passed in the blink of an eye.

The reconstruction of the naval base was nearing completion.

The Bulin construction corps had modeled it after Azure Lane Port, transforming the island where the base stood into a multi-functional military harbor fit for the interstellar age.

Not only had the original port area been expanded more than tenfold—stretching from the coastline all the way to the offshore zone—

All kinds of supporting facilities were also in place.

Next to the port's main structure was a massive starship landing base, large enough for small and mid-sized starships to land, undergo maintenance, and be refitted.

The munitions factory and carrier aircraft assembly plant were also industrially upgraded. The outdated WWII-era production lines had been replaced with advanced interstellar weapons systems.

Rows of futuristic anti-gravity buildings stood tall—viewed from above, it looked like a large-scale military base.

At the same time, Bismarck brought good news.

The human governments on this version of Earth offered no real resistance. They quickly surrendered and agreed to become a vassal state of the Starsea Empire.

After finishing up leftover matters at the naval base and assigning a few shipgirls to remain stationed there—

The Kantai Collection world conquest was officially complete.

Setsuna led the expedition team and began their journey home.

Whoosh—

The Eternal Snowfall pierced the clouds, skimming low over the Eurasian continent.

The neatly arranged building clusters below earned gasps of awe from the native shipgirls.

In a sense, the Starsea Empire was an intelligent-machine empire.

Aside from research being managed by Black Bullet lolis, most of the basic and productive labor was handled by the Bulins and Angeloids.

All across Earth, fleets of starship Bulins and swarms of flying Angeloids busily moved about.

Each continent had a specialized role—industrial zones, agricultural zones, raw material processing areas, and so on.

It all appeared orderly—with a hint of fantastical flair.

When they landed at the base near the capital city, the native shipgirls were stunned by the sheer scale of Constantinople.

It was a super-city hundreds of times larger than any human metropolis.

Rather than a capital city, it looked more like a nation unto itself.

The urban area stretched across the Balkan Peninsula and much of the Anatolian Plateau.

The Sea of Marmara looked like a small lake in comparison.

The imperial administrative center towered into the clouds, showcasing the Starsea Empire's staggering technological prowess and wealth.

Within the city, thriving residential districts bustled with lolis, shipgirls, Bulins, Spirits, and more walking the streets.

Outside the city lay institutions like the Imperial Research Institute, Imperial Magic Academy, and Imperial Starship Academy—each the size of a major modern city.

"So this is the civilization Admiral built from scratch...? Incredible..."

Shoukaku, arm in arm with Setsuna, marveled in genuine admiration.

Seeing the Starsea Empire's power with her own eyes, she realized just how remarkable her Commander truly was.

"This was the result of everyone's hard work."

Setsuna patted Shoukaku's head. She leaned her head on his shoulder and smiled sweetly.

"I feel like living here with you would be pure happiness."

Stare—

Not far away, Richelieu, Taihou, Belfast, and other Azure shipgirls narrowed their eyes at the two.

What was with this overflowing housewife aura coming off Shoukaku?!

She had always been a shipgirl full of feminine charm.

After spending two weeks with the Commander, that vibe had only grown stronger.

Even Setsuna now seemed to have no desire to leave her side.

"Geez, we used to worry the shipgirls from the other world were having a tough time and thought we'd need to support and care for them more."

"Looking at it now... maybe we worried a bit too much?"

Formidable said while playing with her hair.

Going on an expedition with the Commander was fun. Meeting shipgirls from another world was also fun.

But why did combining the two make things feel... a little complicated?!

Seeing the native shipgirls getting eager, the Azure shipgirls felt a sense of crisis.

There were quite a few Yamato Nadeshiko types among them, like Shoukaku—Akagi, Yamato, and others fit the mold too. And it seemed the Commander had a weakness for that type.

"Having more shipgirl companions around the Commander isn't so bad. It's always lively when everyone's together."

Belfast replied nonchalantly.

She was already used to the lively atmosphere aboard the Eternal Snowfall.

"Head maid, that's easy for you to say—you're a well-fed shipgirl!"

Azure Shoukaku gave her a resentful look.

"Of course you're fine. The Commander's already fed you well. Have you even considered how the rest of us sisters feel?!"

...

Later that day—

In the administrative center, all companions—Shipgirls, Spirits, Heroic Spirits, and more—gathered.

This expedition hadn't yielded any new advanced tech or magic.

The biggest harvest?

They had brought back several hundred shipgirls, along with Northern Princess and her family.

Inside the conference hall, the native shipgirls curiously struck up conversations with Spirits, Heroic Spirits, and dragon girls.

If the Azure shipgirls they'd met earlier still made sense as just more technologically advanced "noble ladies,"

These magical beings were completely beyond comprehension.

"And with that, the Kantai Collection world conquest is complete."

"That world is now fully under the Starsea Empire's administration, and will exist henceforth as one of our vassals."

Setsuna gave the room a quick rundown of what happened.

The process had been straightforward—thanks to overwhelming technological superiority, they'd trampled the Abyssal Fleet, and even brought Abyssal Yamato back.

Observer, Tester, and a few other Sirens listened with great interest.

"Another world's shipgirls... and an Abyssal Fleet?"

"Able to endlessly respawn their Abyssal fleet as long as they're at sea? No wonder humans and shipgirls there couldn't defeat them."

Observer rested her chin on her hand, the tentacle rigging behind her wriggling slightly.

"Ah... I really want to run some experiments on them..."

"???"

"Experiments?!"

Yamato, Nagato, and the other native shipgirls were horrified by her octopus-like rigging.

Their minds immediately jumped to all kinds of... questionable scenarios.

Sirens were terrifying—even worse than the Abyssals.

Abyssals might kill you in a fight, but Sirens would abduct you with their tentacles for experiments.

"Stop! You're scaring the natives. Put that thing away."

Setsuna glared at Observer and motioned for Ikaros to bring in Abyssal Yamato.

Mmm mmm mmm mmm mmm—

The clumsy angel tossed the tightly-bound prisoner onto the floor.

With a rag stuffed in her mouth and rope tying her up in a tortoiseshell pattern, she wriggled helplessly like a salted fish.

Even the shameless Sirens were impressed by the Commander's... creativity.

"She's all yours. As the Abyssal Fleet's Supreme Flagship, she should be directly connected to their strange abilities."

"See if you can learn anything useful from her."

Setsuna nodded toward Observer.

He was particularly curious about the Abyssals' ability to rapidly mass-produce and revive units at sea—it could be a valuable research subject.

"Thank you, Commander~ Come visit anytime~"

"Tsk, between the Allspark and now the Abyssal Fleet, I'll be busy for a while..."

Under Abyssal Yamato's horrified gaze, Observer twirled her tentacles and dropped the bound flagship into a strange container before carrying her off.

"..."

Everyone else gave a moment of silence.

"Ahem. We've got plenty of work ahead of us."

Setsuna turned toward the native shipgirls, whose eyes were full of anticipation.

"We need to refit our new shipgirl companions and upgrade Northern's family."

"Shipgirls must be transformed into interstellar shipgirls. Fortresses into interstellar fortress girls. Eternal Snowfall into a Juggernaut-class..."

"Once all that's done—then we can go bully the next world of natives!"

...

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