Crossover Shipgirls: Building a Dimensional Empire from Scratch

Setsuna couldn’t make sense of Grey’s bizarre, mischievous-sounding statement. But seeing the confidence on her face—and that of the other Science Division members—he decided not to ask further.

Bzzz—

The starship activated its optical camouflage, slowly descending from the outer atmosphere.

The hatch opened, and several shuttles were deployed.

”Move out. Quickly.”

—1951, Berlin—

It was an ordinary day.

After centuries of development, Schicksal —armed with the knowledge preserved within the Void Archives—had transformed the city into a dazzling metropolis.

From its architecture alone, one could see that it had reached a level nearly indistinguishable from a modern society.

The streets bustled with cars, and the people went about their daily lives as usual.

But then, without warning—

BOOM—

The Honkai descended.

A surge of indescribable energy erupted from the city’s center, leveling the metropolis in an instant.

Smoke and fire engulfed the skyline.

The city was reduced to a hellscape within moments—no trace of life remained on its streets.

The violent shockwave and seismic tremors spread for miles, and within minutes, the blaring of alarms filled the air.

At first, the Schicksal forces stationed nearby believed they were under attack.

But thanks to centuries of relentless research into Honkai energy, their scholars quickly determined the truth.

It was a Honkai Eruption.

And one far greater than any before.

The initial energy release exceeded 1000 HW.

Rescue teams and exploration units were immediately dispatched into the ruins.

The devastation was total. The city lay in shambles, consumed entirely by the Honkai.

Only a few survivors could be pulled from the outskirts; the center had become a lifeless exclusion zone.

”...”

Yet, amid the rubble of collapsed skyscrapers and twisted metal—

At the very heart of the eruption—they found something strange.

A young boy, kneeling amidst the destruction, staring blankly at his surroundings.

”A Herrscher!!!” shouted one of the explorers in alarm.

According to old records, whenever a Honkai Eruption reached instantaneous power levels exceeding 1000 HW, there was a high probability that a being known as a Herrscher would be born.

They were emotionless, merciless beings who attacked humanity without hesitation—driven by an instinct to annihilate civilization.

But this boy... showed no hostility.

He simply looked around in confusion.

Click—

Desperately, he tried to use his power to save others. But his strength soon failed him, and he collapsed unconscious.

”Target has lost consciousness. Retrieve him.”

The Schicksal recovery team was just about to move in when—

BZZZ—

A shadow swept over them.

A shuttle descended from above.

Fu Hua stepped out, accompanied by the Angeloids, landing gracefully on the ground.

”Hmm? So this is the Herrscher of Reason? Quite... unexpected.”

She glanced down at the unconscious Welt Joyce, then waved her hand.

The Angeloids swiftly placed him into a stasis capsule and secured him for transport.

”Aw, come on! He fainted already? I wanted to spar with him!” Senti pouted.

”Who are you?!” shouted the Schicksal troops, stunned by the sudden intrusion.

Seeing their target stolen before their eyes, they naturally refused to stand by.

The mysterious ship that had appeared out of nowhere—its origins were completely unknown.

A squad of soldiers raised their weapons and advanced.

Fu Hua’s blade flashed.

”Stand down.”

Shhh—

The nearest soldiers fell in an instant.

Even against modern firearms, the immortal of Shenzhou showed not the slightest trace of fear.

Senti, bored as ever, grinned and leapt into the fray—bashing aside opponents left and right just for fun.

It wasn’t until Fu Hua reminded her of the mission that she finally stopped.

Whoosh—

The shuttle acted swiftly. With the target secured, it wasted no time firing its thrusters and streaking toward the north.

”That’s it for this temporal node. Next... the scientists, right?”

Fu Hua glanced over the files, then turned to the small blue-haired loli beside her, twin tails swaying.

”Nymph, I’m not great at dealing with scientists. I’ll leave that to you.”

”No problem! This is Master’s order!” the Angeloid replied confidently.

”Honestly, scientists are the easiest to deal with when they’re obsessed with research, hehe...”

”???”

It wasn’t until the starship’s exhaust vanished beyond the horizon that the Schicksal soldiers finally snapped out of their daze.

”That woman with the sword—who was she?” one asked.

”Why do I feel like she looked exactly like that immortal from Shenzhou who stopped Schicksal ’s Eastern Crusade centuries ago?!”

”You mean the immortal who piloted the flying ship?! And that vessel—what is it?!”

The soldiers stared at each other in disbelief.

”Quick, report this to Lord Otto!”

...

Thousands of miles away, in London—

On the outskirts of the city stood a massive laboratory marked with the insignia of Schicksal .

Inside, several young women were hard at work.

”Einstein, send me the results from the last Honkai energy experiment.”

The speaker was a green-haired, amber-eyed scientist. Unlike most of her colleagues, she looked remarkably young—barely in her thirties—and carried herself with elegant composure.

”Yes, ma’am.”

Not far away, another girl in a white shirt and light sweater responded.

Her short, wavy blonde hair framed a face so delicate she could have been mistaken for a porcelain doll—if not for the faint air of chaos that betrayed her as a mad genius. Her name was Lieserl Albert Einstein—one of humanity’s greatest scientists.

At this time, she was already beginning to make her mark, working within Schicksal ’s Imperial laboratories.

Her research encompassed not only traditional physics but also the utilization and transformation of Honkai energy.

”Once we finish this project, we might have to visit the North American branch...”

The scientists chatted casually as they worked.

Then suddenly—

Beep—

An urgent transmission blared through the lab.

Planck and Einstein rushed over immediately.

”A Honkai Eruption has occurred!!!”

The report sent a chill through the room.

On the digital map, the exact coordinates of the first Honkai Eruption were marked in red.

”Should we go there? Or wait for orders from Schicksal headquarters?”

”No. It’s too dangerous right now. A high-energy Honkai burst like that could produce a Herrscher—we should wait...”

Before they could finish their discussion—

BZZZ—

The roar of engines filled the air outside.

The laboratory’s communications abruptly went dead.

”???”

Einstein and Planck turned toward the window—only to see a silver ship hovering directly above the facility.

In the blink of an eye, the Angeloids descended, effortlessly wiping out Schicksal ’s security forces.

”Are we being... robbed?!” one of the scientists cried, trembling.

But then she realized—

It didn’t make sense. Who would come robbing in a state-of-the-art antigravity craft? And they were just researchers—hardly worth looting.

Click—

Nymph landed before them, flanked by several Angeloids.

”Oh...”

The sight of the angelic beings—white wings, radiant halos, and flawless faces—left the scientists momentarily dumbfounded.

”Hmm, quite a few people here, huh?” Nymph glanced around casually.

Einstein, Planck, Schrödinger—all the major names of future history were present.

In the Honkai universe, every one of humanity’s most famous scientists was, of course, an adorable girl.

”To put it simply, we’re from the Starsea Empire. Master has taken an interest in your work and invites you to come aboard.”

The little loli gestured politely toward the ship.

”?”

Einstein and Planck exchanged baffled looks.

”Starsea... Empire...?”

Although Schicksal classified all information regarding the Starsea Empire as top secret, as senior researchers, they had heard fragments of the legend.

Now, seeing the impossibly advanced starship hovering above, old memories began to resurface.

”Yes, it’s exactly what you think—the same Starsea Empire recorded in history,” Nymph replied cheerfully.

”Suspicious,” Einstein murmured, chin resting on her hand as she studied Nymph.

A strange group suddenly appearing, claiming to represent a forgotten civilization, and inviting them to meet some mysterious ’Master’—it all sounded absurd.

Especially right as the first Honkai Eruption had just begun.

Even as a scientist driven by curiosity, Einstein hesitated.

But Nymph’s next words froze her in place.

”Lieserl Albert Einstein—you recently completed your doctoral thesis, right? On General Relativity 1.1?”

”Ah—uh, yes...”

Einstein answered instinctively.

”It’s a brilliant theory. Hugely influential. It used to be part of the Starsea Empire’s elementary curriculum.”

”Elementary...?” Planck blinked in disbelief.

”It’s based on the constancy of light speed and the principles of Special Relativity, correct?”

”O-oh... yes, that’s right.”

Einstein hadn’t expected the little girl to know her work so well.

”But your theory could use some refinement later on,” Nymph said matter-of-factly, pointing out the window.

”See that ship? Faster-than-light.”

”We can also generate dark domains, reducing vacuum light speed to 30 meters per second—allowing us to navigate higher-dimensional space, travel through time, and cross thousands of light-years via jump drives.”

”???”

”What—what did you just say?!” Einstein, Planck, and Schrödinger all gasped as if hearing pure nonsense.

Nymph simply smiled again.

”So, are you coming or not?”

...

”So this era’s greatest scientific minds are all here now.”

Half a day later, aboard the starship’s command bridge—

Nymph stood proudly before Setsuna, a group of girls lined up behind her.

”This is Einstein, this is Edison, this is Tesla...”

The ship’s young researchers stared in awe at the legendary scientists they’d only ever seen in textbooks.

Edison was a tall, confident woman with blue hair tied into a high ponytail and piercing red eyes.

Einstein had naturally curly hair, a shirt-and-jacket combo, and black stockings that made her look both scholarly and charming.

Tesla, with her red hair and twin tails, looked so much like Kotori Itsuka that Setsuna almost did a double take.

Alongside them were Schrödinger, Planck, and other forebears of modern science.

Though it was still early in their careers—they had yet to make the world-shaking discoveries that history would remember them for—most had already begun to rise in prominence.

Some had been recruited by Schicksal to research Honkai-related technologies. Edison, for example, was currently the CEO of General Electromechanics, worth billions.

But regardless of their individual circumstances, none of these brilliant women could refuse an invitation from a supercivilization.

To witness technology beyond imagination—that was an irresistible lure.

”...”

Kayo Senju and Midori Fuse, who had accompanied Setsuna, skimmed through the holographic profiles and then looked at the assembled scientists before them. Their expressions shifted several times.

To think—these were the people whose theories they had studied growing up.

And now, those textbook legends stood before them as natives of a less advanced age.

Even more shocking—every single one of them was a girl.

”...Whatever. We’ve seen other worlds where King Arthur and Nero are both girls. Nothing new here.”

Kayo rubbed her temples and stepped forward with Setsuna to greet their new guests.

”Welcome to the Starsea Empire. I’m Kayo Senju, Director of the Imperial Science Division—and this is the Commander of the Empire.”

”Simply put, we’d like to invite you to join our Science Division. We’ll provide you with far more advanced equipment and share our knowledge with you.”

”Together, we’ll explore the secrets of other worlds.”

”Oh...”

Edison stared at the little loli for a long moment, barely able to believe that such a young girl could already be leading a scientific division.

”Hey, she’s even more of a genius than you. Didn’t you finish your PhD at seventeen?” she teased, nudging Einstein.

”Ngh...”

Einstein glanced around. Nearly everyone aboard was a young girl in a lab coat—save for a few exceptions.

”This is simply the result of advancements in bioengineering,” Kayo replied modestly.

”Huh...?”

”You mean you’ve used biological technology to enhance intelligence?” Einstein quickly realized, her curiosity piqued as she began to examine her surroundings.

”This ship—it’s antigravity-based, isn’t it? What’s its power source? Honkai energy? Can you really exceed light speed? Is that even possible? What kind of mechanism allows that?”

”Hiss... looks like I’ll have to rewrite my entire theory...”

Her barrage of questions made Setsuna chuckle.

Scientists would always be scientists—utterly consumed by their hunger for knowledge.

And for such obsessive seekers of truth, the Starsea Empire’s technological allure made recruitment laughably easy.

”The Starsea Empire’s technology spans countless disciplines—not just physics, astrophysics, and biology, but even the field you’d call ’magic.’”

”If you’re interested, the Science Division can start by teaching you the basics of faster-than-light theory.”

Setsuna snapped his fingers, and the Angeloids handed each of the scientists a sleek tablet.

They contained the Empire’s introductory materials—an overview of the Starsea Empire’s history, technology, and development.

With intellects like these, it wouldn’t take them long to catch up to the rest of the Empire’s researchers.

”No problem!!!” Edison and Planck responded at once.

Not a single scientist could resist the chance to explore an advanced civilization.

Even though they had only spent a couple of hours aboard, just from observing the details of the ship, the scientists had already concluded that the Starsea Empire’s technology operated on a level far beyond human comprehension.

Antigravity, energy shields, artificial intelligence angels...

And, whether intentionally or not, they’d revealed that they came from another world entirely.

As for their personal safety?

When had mad scientists ever cared about that? The Starsea Empire bore them no hostility—in fact, they’d even promised to build each of them a personal laboratory.

A win-win situation. Pure profit.

”Parallel universes... No, beyond this universe there are others...”

The group quickly lost themselves in the flood of new information.

”Hmm, looks like cosmology will need a major rewrite...”

”And the applications of Honkai energy...”

After half an hour of animated discussion, they suddenly realized how impolite they were being.

Straightening their coats, they cleared their throats and bowed respectfully to Setsuna.

”Ah—sorry, we got a bit carried away.”

”It’s fine,” Setsuna replied with a grin.

In the original timeline, these very scientists had gone on to create miracles—the Moonlight Throne, Star of Eden, and countless other wonders.

Here, in the Starsea Empire—with better resources and the support of the Angeloids—their potential was boundless.

He couldn’t help but look forward to what they would create next.

”Earlier, I heard you’ve retrieved the first Herrscher. May I ask—what do you plan to do with him?” Edison suddenly asked.

”Hmm...” Setsuna paused to think.

”After separating the Herrscher Core from him, we’ll restore his memories and return him to live as a normal human.”

Better that Welt Joyce live peacefully as a man than be captured by Schicksal and turned into an endless lab experiment.

Besides, the Empire had countless vassal worlds where he could easily settle.

Of course—

With the first Herrscher and the world’s leading scientists all removed, the future of the Honkai world would change dramatically.

Originally, Schicksal ’s conflict with Einstein and Planck over Herrscher research had led to their defection—and the founding of Anti-Entropy, sparking centuries of rivalry and strife.

But now, with all of them joining the Starsea Empire, Anti-Entropy would never exist.

Schicksal would likely be left completely dumbfounded.

The future’s direction had splintered into countless possibilities, all neatly mapped out by Grey’s simulations.

”...Separate the Herrscher Core?” Edison and the others stared in awe, both confused and impressed.

”Could we see how it’s done?”

”Mhm,” Setsuna nodded toward the Science Division.

On Honkai Station-1, the researchers had already mastered Honkai energy manipulation—this would be easy for them.

”Don’t worry—it’s simple! Easier than a minimally invasive surgery!” Kayo Senju said confidently.

...

A day later—

While Setsuna was planning their next temporal destination, the Angeloids delivered a containment unit sealed within an energy field.

Inside floated a translucent crystal, faintly radiating power.

”All done. This is the Core of Reason—the first Herrscher Core,” Kayo reported.

”Welt Joyce’s memories have been modified by the Herrscher of Sentience and he’s been relocated to another vassal world.”

”Good.”

Setsuna studied the crystal carefully.

The Herrscher of Reason—

Her power was Understanding and Replication.

Once she fully comprehended and explained the structure of an object, she could recreate it purely through her own energy.

Be it an assault rifle, a starship, or even a Divine Key—so long as she understood its mechanism and function, she could reproduce it.

A blend between imagination manifest and projection sorcery—a truly versatile ability.

”Hmph, collecting them one by one is too slow. We might as well take care of the Cocoon of the Finality next time.”

Click—

Setsuna inserted the core into the starship’s interface slot.

The Herrscher Core Drive Module—crafted by the Science Division during their first expedition to the Honkai world—hummed to life.

[Core of Reason successfully integrated.]

As the AI’s voice echoed, a surge of power flowed through the ship—and into Setsuna himself.

”Hmm...”

He clenched his fist, feeling the new strength coursing through him.

The energy was of the same origin as the Herrscher of Corruption’s, yet distinctly different in its expression.

”Not bad.”

Merging the power into his body, Setsuna turned toward Fu Hua, Senti, and the others.

”Well? What do you want? I’ll make you something as a test.”

”...”

Grey tilted her head thoughtfully.

”How about a Dyson Sphere? For fun?”

”?”

—

—

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