Crossover Shipgirls: Building a Dimensional Empire from Scratch

The treaty document was dozens of pages long, its wording and phrasing exuding the grandeur of a formal diplomatic declaration.

The level of effort and seriousness the shipgirls of the harbor had invested was clear.

Setsuna read through the document carefully. At its core, the content was relatively straightforward.

• Trade Agreement: Azur Lane would send a Vanguard Fleet to help rebuild civilization on Earth while extracting resources from the planet. A portion of these resources would be periodically delivered back to the harbor as compensation.

• Immigration Agreement: Shipgirls were permitted to travel freely between the two worlds and choose their place of residence, whether in the harbor or on Earth. Setsuna was required to guarantee their citizenship.

• Military Alliance: If either side was attacked, the ally was obligated to intervene for mutual defense. The Vanguard Fleet would accompany Setsuna to other worlds for military campaigns, and in turn, he was duty-bound to assist the harbor in eliminating the Siren threat.

The rights and obligations were balanced, with every detail meticulously specified.

The agreement was designed to be fair and just, leaving no room for objections.

"I agree."

Setsuna signed his name on the document.

"We are delighted to work with you."

Enterprise, representing the harbor, signed her name as well.

The gathered shipgirls erupted into cheers and jubilant applause.

"Woohoo!!"

After the treaty was signed, preparations for the Vanguard Fleet's deployment to Earth began in earnest.

The harbor buzzed with activity as resources were gathered and the exploratory fleet was assembled.

Their priority was ensuring they could quickly establish a foothold and build a basic industrial system once they arrived on Earth.

Everywhere, Manjuus and Bulins were busily loading shipping containers with construction materials, ship fuel, coolant, and other essentials for shipgirl life.

By rough estimation, the supplies were sufficient to construct a small naval base.

The Royal Navy shipgirls even packed some breadmakers, tea sets, and their unique culinary specialties, like Stargazy Pie.

"Since our main forces need to remain here to defend the harbor, the Vanguard Fleet will be relatively small."

"We'll keep it to a standard combat fleet of 24 shipgirls, plus a contingent of support Bulins. If needed, we'll send reinforcements later."

Enterprise addressed the gathered shipgirls in the harbor plaza.

"Who wants to join the Vanguard Fleet and explore the new world?"

"Me, me, me, me!!!"

"Pick me, pick me!!!"

The enthusiasm from the shipgirls was overwhelming, as they eagerly raised their hands and surged forward.

The smaller destroyers were especially relentless, pushing their way to the front.

"Yukikaze wants to see the other world!"

"Javelin wants to go too!"

"All four of the Kongou sisters are signing up together!!!"

"Commander, choose me! Choose me!!"

The flagship representatives were momentarily stunned by the uproar.

"If everyone leaves for the other world, what happens when the Sirens attack?!"

"Then we'll just hand the harbor over to the Sirens and move to the other world to live with the Commander!"

A certain French shipgirl suggested boldly.

Bonk!

She received another firm knock on the head.

Clearing her throat, Richelieu addressed the passionate crowd.

"To ensure fairness, I will lead the Vanguard Fleet. Each faction will contribute three shipgirls."

"We depart tomorrow morning!"

The Next Morning—Harbor Plaza

The plaza was packed with shipgirls, forming a dense sea of bodies.

Richelieu stood in front of Setsuna with the 30 selected members of the Vanguard Fleet.

"These are the members of our first Vanguard Fleet."

"Once we arrive on the other side, we'll be under your command, Commander."

Setsuna glanced at the gathered fleet.

The lineup included carriers, battleships, cruisers, and destroyers—all fully equipped.

Naturally, Akashi, the cunning merchant and victim of a Wisdom Cube theft, was also present, likely preparing to open a chain store in the new world.

This Vanguard Fleet would have been a nation-destroying armada back on Earth.

The chosen shipgirls seemed excited to meet Setsuna.

"Hohoho~~, we meet again, Commander."

"Listen carefully! I am the noble, lucky, and invincible Yukikaze, the eighth ship of the Kagerou-class destroyers!"

"Having me in your fleet is a blessing, so rely on my luck, hohoho~~"

A cat-like ears shipgirl in a sailor uniform with white hair and amber eyes stood with her hands on her hips, looking up at Setsuna with a proud expression.

"Alright, alright."

Despite Yukikaze's reputation in history for being a bit of a troll teammate, Setsuna figured her legendary survivability and uncanny luck would make for some amusing moments in the future.

"Commander-sama, do you remember me?"

"Hmph, so many pests here, but it doesn't matter. The Commander is mine and mine alone… Hehehe."

A heavy Sakura Empire shipgirl stood before Setsuna, her eyes gleaming with a possessive, almost unhinged intensity.

Dressed in a daringly short red kimono, the fabric clung to her figure, the intricate golden embroidery accentuating her curves while exposing a generous view of her thighs and the alluring swell of her chest.

Her ample chest pressed dangerously against the thin silk, the flimsy fabric straining with each deep inhale as if threatening to spill free. The plunging neckline revealed the creamy expanse of her décolletage and offered a tantalizing display of her cleavage, an intoxicating sight that drew the eye and quickened the heart.

The slit in the kimono a revealed striking view of her charming legs, wrapped in black stockings as she moved. Her heels, polished and adorned with intricate details, clicked softly against the floor with every step.

Her long, obsidian hair cascaded down her back in silken waves, accentuated by crimson ribbons that added an air of elegance to her otherwise provocative appearance.

Behind her, her rigging flared out in a fan-like formation, resembling the majestic tail of a peacock, its sharp, mechanical edges contrasting starkly with her seductive charm.

Her presence was intoxicating—a perfect blend of beauty and danger.

"Taihou?!"

Setsuna felt a sudden chill down his spine.

Fortunately, the fleet also included I-19 and I-401, as well as Essex from the Eagle Union. They should help keep Taihou in check.

The Royal Navy contingent—Illustrious, Formidable, and Belfast—stood out as the faction with the largest average cup size.

Even the small Eastern Radiance faction managed to contribute Yat Sen, Ning Hai, and Ping Hai.

At the rear of the formation stood a precise square of purple Bulins.

Led by a single colored Bulin, they all carried oversized wrenches. Their identical outfits, expressions, and even the angles of their ahoges made them look like clones—only their chest-mounted numbers differentiated them.

"Commander, come back to visit us often!"

"I still want to hear stories about the other worlds…"

A petite shipgirl in a naval uniform with a bob cut clung to Setsuna's sleeve reluctantly.

"There'll be plenty of chances to meet again. Once we defeat the Sirens, all of you can move over."

"Maybe we'll even upgrade you with better rigging—like something akin to the Type 055 Destroyer."

Setsuna ruffled Tai Yuan's hair, earning a small smile.

Then, concentrating, he stretched his hand toward the void.

"All units, prepare for departure!"

Hum!

A higher-dimensional power tore through space, opening a massive temporal portal.

...

After a cascade of dazzling lights, solid ground met their feet once again.

Before them stretched a barren, desolate world, lifeless and bleak.

Since it was their first time setting foot in another dimension, the Azur Lane shipgirls curiously took in their surroundings.

"So, this is the Commander's world?"

"Hm… it's slightly better than I expected. At least it's not a nuclear wasteland."

Belfast sniffed the air, picking up the earthy fragrance of soil and the scent of nearby forests.

Some of the more excitable shipgirls darted off, chasing tigers, wild boars, and bears, sending the animals scurrying in all directions.

"Is that where you lived before?"

Essex pointed to the small wooden cabin by the forest's edge.

A month of exposure to the elements had left the cabin dilapidated, barely standing.

"That was my starting point, I guess. There are some tools and supplies inside—flour and rice—but I doubt we'll need them anymore."

Setsuna glanced at the cabin and shrugged.

"Since we're helping the Commander rebuild civilization here, the first step is to draft a construction plan."

As the fleet's flagship, Richelieu took charge without hesitation.

"Formidable, confirm our current location and scout the surrounding terrain."

"Understood."

The twin-tailed aircraft carrier activated her rigging, launching two carrier planes.

Initially toy-sized, the planes rapidly expanded mid-air into several-meter-long war machines, roaring into the distance.

When Setsuna had first arrived, the architectural style suggested he was in Europe, but pinpointing the exact location had been impossible.

It wasn't long before Formidable received data from her reconnaissance planes.

"Current coordinates: 50.7° N, 8.4° W. Based on global maps… we're near Frankfurt, in Western Europe."

"The scout planes report no signs of human activity within a 300-kilometer radius. The area is mostly forested with scattered wildlife."

Since this world's terrain mirrored the Earth he knew, Setsuna's old maps were still usable.

"We're inland…"

Richelieu tapped her chin thoughtfully.

"What's the nearest access to the sea?"

"Heading north along the Rhine River, we can reach the North Sea. Going south, crossing the Alps will take us to Italy, where Venice offers a good port city connected to the Mediterranean."

Setsuna spread a map on the ground, pointing to locations as he explained.

"I see…"

"Commander, where do you think we should start?"

"North, south, or should we build a city right here?"

Richelieu's gaze was expectant.

The first city in this world would serve as the cornerstone of their civilization, the foundation of future development and their eventual capital.

"What's everyone's opinion?"

Setsuna turned to the lead shipgirls for their input.

"I suggest heading north to build a port by the North Sea—like the harbor we came from," Formidable said, twirling a strand of her hair.

"After all, we're shipgirls. Living by the sea feels natural."

"I disagree."

Belfast shook her head.

"Since this is the Commander's world, we should consider his needs. The North Sea's harsh climate isn't suitable for human habitation."

"Building a city here using local resources is the best choice."

The ever-dedicated maid prioritized Setsuna's well-being above all else.

"I think we should head south, meow!" Akashi raised her hand.

"Venice is larger than any North Sea port, and the weather is milder."

"If we build inland, later development will be much harder, meow. We'd have to construct a road and rail network from scratch."

"If we're by the sea, meow, we can solve most problems with shipping."

The shipgirls argued passionately, each presenting valid points.

Ultimately, all eyes turned to Setsuna for the final decision.

"Hm…"

Setsuna rubbed his chin in contemplation.

Each option—north, south, or staying put—had its advantages.

Building locally was the simplest and allowed for easy access to mineral resources. However, the lack of transportation infrastructure would complicate future city expansion.

While the shipgirls were naturally suited to maritime environments, their technological expertise skewed heavily toward naval warfare. Setsuna doubted they had unlocked agriculture or light industry on their tech tree.

A northern port offered excellent connectivity via sea routes but would be limited in scale and subjected to the cold, harsh climate of higher latitudes.

As for Venice, while its location in the Mediterranean was appealing, the city wasn't large enough to support a comprehensive industrial and agricultural system.

He pondered deeply. None of the options seemed ideal.

"Is there a location with enough land area for future highways, railways, and airports, a port suitable for shipgirl habitation, and convenient access to both sea and land routes connecting continents?"

"Preferably one with abundant nearby resources, too…"

His eyes scanned the map.

"Commander, your standards are too high! There's no place like that…"

Formidable pouted.

"Got it! Here!"

Setsuna's finger landed firmly on a spot on the map.

The others leaned in to see.

It was a location at the crossroads of Europe and Asia, marking the boundary between the two continents.

Constantinople.

This city could connect the entire continent via land routes while also granting access to the seven seas through the Mediterranean.

For a significant part of history, Constantinople was the world's largest city, famously known as the Queen of Cities.

After the fall of the Eastern Roman Empire, it was renamed Istanbul and transitioned into the modern era. Despite its decline, its strategic geographical position and historical significance had never waned.

"This city was once the capital of the Roman Empire."

"And it will be the starting point for our voyage through the endless sea of stars."