Crossover Shipgirls: Building a Dimensional Empire from Scratch

Setsuna felt like he had entered a grand strategy game like Civilization or Stellaris, except the nations were replaced with worlds from the multiverse.

And he was starting out as a primitive indigenous with absolutely nothing.

The Dimensional Diplomacy ability was extraordinarily powerful. Even gods and demons might lack the ability to perceive the multiverse as a map, let alone freely traverse other worlds without conditions. Its potential was immense.

But looking at the surrounding neighbors, each labeled ”Like a God,” Setsuna couldn’t shake off the subtle feeling of, ”Man, I’m so weak.”

”Well, let’s figure out how to complete the initial quest first.”

Recruiting 20 individuals meant he’d have to turn to other worlds for help—he certainly couldn’t split himself apart to make more people.

Setsuna scanned the map, and his gaze eventually landed on the Honkai Universe and the Azur Lane Universe.

Considering the unpredictable nature of Honkai energy, he decided to contact the Azur Lane world first.

He had, of course, played this game before.

Its core premise was battling Sirens alongside shipgirls.

The game’s ”specialty”? Teetering on the edge of R18 content, repeatedly.

Thanks to these games that anthropomorphize military hardware, now even hardcore otakus were calling the Type 055 destroyer their ”waifu.”

On the star map, he reached out and tapped the Azur Lane world. Detailed information immediately appeared:

[Azur Lane: Pre-Space Age]

• A predominantly oceanic world inhabited by beings called Shipgirls, engaged in an unending war against the Sirens.

• This world possesses a unique technology tree, with highly advanced military technology and a trace amount of magical power.

Comparison of Strengths:

• Technological Level: Like a God.

• Military Strength: Like a God.

• Economic Power: Like a God.

[Options:]

• Diplomacy

Setsuna tapped the holographic interface.

Zzzt

The screen flickered.

[Contacting faction leader…]

[Language auto-translation system activated…]

[Communication established!]

In the Azur Lane world, at the harbor—

A blonde-haired shipgirl, engrossed in her paperwork, suddenly froze in shock.

She looked up to find a large holographic screen, the size of a movie screen, materializing abruptly in front of her.

On the screen, Setsuna’s avatar was clearly projected. He waved and greeted her:

”Hey? Hello? Can you hear me?”

It seemed he had successfully contacted the nominal leader of the Azur Lane world.

”G?!”

The shipgirl jumped, spilling coffee all over her desk.

After hurriedly cleaning up the mess, she glanced around nervously before focusing on the holographic interface.

Steadying herself, she adjusted her clothes, cautiously materialized her rigging, and fixed her eyes on Setsuna.

”Well… hello?”

”Welcome to the Azur Lane main harbor.”

”I am Richelieu, flagship of the Richelieu-class battleships from the Iris Libre faction. May I ask who you are?”

The two conversed across worlds through the holographic projection.

The girl had golden hair and violet eyes, wore a long red-and-white dress, and kept her hair in an elegant style.

Her appearance was exquisitely refined, far surpassing that of any human, even the most stunning celebrities on Earth.

But the most striking feature was the rigging behind her.

Two quad-barreled main guns stood prominently, with countless secondary cannons guarding her flanks, clearly set in a combat-ready posture.

”Relax, I mean no harm.”

”I’m your neighbor,” Setsuna introduced himself succinctly.

”Neighbor?”

”I don’t recall there being any humans in or near the harbor... Are you with the Sirens?”

Richelieu looked slightly confused.

”No, I’m from the adjacent universe. Our worlds are next to each other.”

”Ha???”

It took a while to explain things to the utterly baffled shipgirl.

Fortunately, since Azur Lane’s technological level was relatively advanced, Richelieu quickly grasped the concept.

The so-called ”neighbor” was actually separated by an entire universe—a distance of hundreds of trillion of light-years.

They were having an interdimensional conversation.

”So, you’re saying there are other people outside of our world? Hmm, I’ve never thought about that before…”

”No, we haven’t even left our planet yet…”

Richelieu tugged at her golden hair, deep in thought.

”And by ’neighbor,’ you mean there are other worlds nearby?”

”Of course. So far, I’ve identified five. Your world is among the more technologically advanced ones.”

Not wanting to overwhelm her with concepts like Spirits, Herrschers, and demons from other universes, Setsuna kept his explanation simple.

”Oh.”

Richelieu nodded, a note of admiration in her tone.

Initially, she doubted whether Setsuna was telling the truth, but then she realized—if someone had the power to communicate across space and dimensions, why would they waste time deceiving her?

After pondering for a moment, Richelieu returned to the matter at hand:

”Well then…”

”Mr. Setsuna, may I ask why you’ve contacted the harbor?”

Assuming that someone capable of initiating interdimensional communication must come from an unimaginably advanced civilization, she spoke with great respect.

”…”

”I want to learn more about your harbor’s situation,” Setsuna replied seriously.

”And while we’re at it, are you interested in signing a migration agreement? Maybe throw in a mutual non-aggression and joint defense pact too?”

”...”

The shipgirl on the other side was utterly stunned.

From the moment she received the interdimensional communication and heard about the multiverse concept, Richelieu’s brain had been overloaded with information.

When Setsuna mentioned migration agreements, non-aggression pacts, and mutual defense treaties, she was left completely dumbfounded.

What was all this? Treaties between worlds? Thinking on such a grand scale?

After staring blankly for a long time, she finally responded:

”You mean… you want to cooperate with the harbor?”

”Yes.”

Setsuna nodded.

His idea was simple—ask if the harbor needed resources like oil or metal ores. He could provide them.

After all, the entire Earth was his now.

All he wanted was for some shipgirls to migrate over and help him with infrastructure development.

”Hmm...”

Richelieu lightly tapped her fingers on the table, lost in thought.

The harbor had been locked in years of conflict with the Sirens, and resource shortages were indeed a pressing issue.

Furthermore, with the seas blockaded, the expedition teams’ operational range was shrinking by the day.

However, collaborating with an unknown individual from another world posed many challenges.

”I’m sorry, Mr. Setsuna. Matters involving two worlds require deliberation among all the major fleets. I cannot make such decisions on my own.”

She nodded slightly in apology.

”Besides, even if you’re willing to supply us with resources, how would you deliver them? The distance between two universes must be at least hundreds of billions, if not trillions, of light-years. The harbor doesn’t have interstellar travel capabilities yet...”

”I’ll handle that part.”

Setsuna replied.

”Are you currently able to receive visitors? If so, I could come over and discuss things in person. Cross-world communication is quite taxing mentally.”

”Huh?”

Richelieu froze again.

”In person? Well… I suppose that’s possible...”

”Will you come by spaceship? How long will it take? When will you arrive?”

”Right now.”

Setsuna pressed the ”Traversal” button on the holographic interface.

[Opening Dimensional Portal: Earth → Azur Lane World]

Swish!

The space before him distorted as a dimensional portal opened, filled with dazzling, chaotic light that swirled like a vortex.

As he stepped through, a sense of weightlessness overtook him, and his entire being vanished from the plane of reality.

Meanwhile, Richelieu let out a startled cry from the other side.

”G?! What is that vortex? A portal? You can traverse worlds freely?!”

”Wait! I’ll send someone to receive you immediately!!”

Azur Lane World

The sky was a vivid blue, and the sea stretched endlessly beneath it, unmarred by even a single cloud.

Boom!

Suddenly, a roaring sound reverberated through the air.

A multicolored dimensional portal tore through the fabric of space, opening slowly above a sandy beach.

The shipgirls playing on the beach felt the ground tremble beneath their feet. They stopped their games, stood on tiptoes, and squinted at the strange phenomenon.

”An earthquake?!”

”What is that thing? It’s black… Wait, there’s a shadow inside!”

”Could it be a new Siren weapon? Or maybe Yuubari’s conducting experiments again?!”

”Should we shoot first and ask questions later?”

The shipgirls gawked at the portal in the air.

The shadow within the dimensional vortex grew larger and closer.

”Waaaah! Someone’s falling out!”

The little shipgirls quickly scattered to make room.

Thud!

Setsuna emerged from the portal, landing firmly on the ground.

”So, this is the Azur Lane world?”

”Why does the dimensional portal feel like a tumble-dryer?”

He rubbed his head, trying to regain his composure.

The traversal between worlds had taken about ten minutes. It wasn’t a pleasant experience—the process consumed a significant amount of mental energy, leaving him slightly dizzy and disoriented.

Thankfully, he had landed near the harbor. If he’d ended up at the Sirens’ base, it would have been a disaster.

He glanced at the system panel.

Cooldown: 29 days, 23 hours, 59 minutes

Unrestricted dimensional traversal came with a one-month cooldown. It wasn’t too long and was manageable.

”Hm?”

Setsuna surveyed his surroundings.

He was standing on a sandy beach, with the azure sea and sky stretching out before him. Not far away lay a cluster of naval-style buildings—likely the Azur Lane harbor.

Around him, a group of curious onlookers had gathered.

Several shipgirl destroyers had even materialized their rigging, watching him warily.

”Isn’t that Yukikaze, Mutsuki, and Kisaragi?”

He recognized a few of the small shipgirls.

”Wow, the alien can talk!!”

The shipgirls screamed and scattered.

”An alien! Aliens are invading! Quick, get Enterprise-senpai!”

Half an hour later.

Breathing in the fresh ocean breeze, Setsuna walked toward the main harbor building, surrounded by a group of shipgirls.

His sudden arrival had caused a minor commotion, but the harbor staff had quickly sent someone to escort him.

A Kingdom of Women.

That was Setsuna’s first impression of the Azur Lane world.

Shipgirls, as the name suggested, were anthropomorphic representations of warships, all taking the form of women.

There were adorable destroyer lolis, youthful cruiser girls, and elegant aircraft carriers and battleship ladies.

The shipgirls lived together in the harbor near the coast.

Additionally, there were small, fluffy yellow birds bustling about, sweeping and handling chores.

These seemed to be Manjuus, the mascots of Azur Lane.

Judging by the size of the harbor, it was far larger than Earth’s largest naval base, the port of Murmansk.

Their technology tree resembled Earth’s in some ways. The designs of certain aircraft and artillery bore traces of WWII-era styles but had been modified with this world’s unique technology.

”Mr. Setsuna, this way.”

”The flagships of the major fleets are waiting for you.”

Crossing a plaza, Setsuna arrived at the entrance of the main building, where a silver-haired shipgirl in a maid outfit curtsied elegantly, her stunning features and refined grace exuding an exquisite charm

”Oh, Belfast, hello.”

Setsuna nodded in greeting.

Guided by the head maid, he was soon led to the top floor, where a reception hall awaited him.

Inside, several shipgirls dressed in formal attire rose to greet him.

”Eagle Union flagship, Enterprise.”

”Royal Navy flagship, Queen Elizabeth.”

”Dragon Empery flagship, Yat Sen.”

”Iron Blood flagship, Bismarck.”

These were the flagships of the major factions.

In the absence of a commander, the Azur Lane world functioned as a federation of fleets, with high levels of shipgirl autonomy.

”A visitor from another world—you are the first human to reach the harbor.”

As the first to interact with Setsuna, Richelieu stepped forward to welcome him.

She was still dressed in her red-and-white short skirt accented with gold trim. Paired with thigh black garters, red stockings clung to her slender legs, the vibrant color drawing attention to their perfect shape. The outfit revealed just enough of her thighs to accentuate her beauty without losing its refinement.

Her look was completed by a pair of sleek black high heels, elevating her stature and adding a striking allure to her every step. Few could pull off such an extravagant style and bold color palette. Without the right presence, it could easily appear gaudy or overwhelming.

Instead, it enhanced her natural elegance, exuding grace and poise befitting a cardinal. Each detail of her attire and bearing enhanced her stunning appearance, leaving an indelible impression.

Her slightly wavy blonde hair cascaded evenly behind her shoulders, and her violet eyes held a blend of determination and noble air.

Richelieu greeted Setsuna in French.

”Bonjour, Mr. Setsuna.”

”Welcome to the Azur Lane harbor.”