Crossover Shipgirls: Building a Dimensional Empire from Scratch

After returning to the Starbase, Aurora underwent a simple inspection, but no issues were found.

Whether it was the lolis’ design or the Bulins’ exquisite craftsmanship, the result had reached perfection.

The shipgirls looked at Aurora with eyes full of envy.

The first shipgirl to surpass the speed of light! Also the first to accompany the Commander on a long-distance space voyage!

A milestone within the port—something worthy of being written into the Empire’s history.

Aurora herself appeared sweet and well-behaved, staying by Setsuna’s side the entire time.

”Commander, are you satisfied with Aurora’s hull?”

”How did the trip feel? If you have time, remember to visit me often...”

She took out a few delicately decorated dried flowers and handed them to Setsuna and the companions who had traveled with him.

”These are flowers I cultivated myself while stationed at the Starbase—a little memento for you all.”

”Mm.”

Setsuna recalled that she did indeed love gardening—and she was a Sichuan girl.

The other shipgirls each received a bouquet—mostly common varieties like lavender and dusty miller.

When it was Setsuna’s turn, Aurora pulled out a radiant bouquet of blooming roses from her rigging.

”Commander, this is the best variety I cultivated—just for you~”

Aurora stood on tiptoe and gave Setsuna a gentle kiss on the cheek before running off with a blushing face.

”???”

”Are you a humanoid succubus or what?!”

Gudako was finding it increasingly difficult to comprehend just how popular Setsuna was among the shipgirls.

”If I throw a stone in the base, I’ll hit nine shipgirls who want to sleep with you.”

”So jealous—”

”Ahem, no, that’s not the point.”

Kayo Senju sized herself up and realized that even if she stood on tiptoe, she still wouldn’t be able to reach the Commander. She’d only be treated like a daughter.

Clearing her throat, she redirected the topic.

”Building a superluminal engine isn’t that complicated. We already have a mature manufacturing plan.”

”With support from the Specialized Bulins, everyone will soon be able to refit into faster-than-light starships, and even install some experimental weapons.”

”Oh?!”

Hearing that their hulls could be modified again, the shipgirls temporarily forgot about Aurora’s bold move.

”We can all travel faster than light and explore the sea of stars freely?!”

Just imagining soaring through the stars, the stars above seemingly within reach, filled everyone with excitement.

”What kind of experimental weapons are we talking about?”

Richelieu asked curiously.

”The Commander probably hasn’t brought back any tech-side weapons from other worlds recently, right?”

”But we do our own research too!”

The science loli stomped her foot like she was pouting.

”Don’t treat us like some reverse-engineering-only group who relies on otherworldly products! Our R&D capability is super strong too!!!”

”Once faster-than-light tech is achieved, the corresponding support systems need to be upgraded as well. It’s not as simple as just swapping out the engine!”

Under Kayo Senju’s explanation, everyone understood a simple truth for tech-side civilizations:

Below lightspeed, all are ants.

The difference between an FTL civilization and a sub-light one is qualitative.

It’s not just about ships flying faster.

Once you enter the FTL threshold, the very foundations of science enter an entirely new tier.

The gap is even greater than going from geocentric theory to relativity.

On the scale of interstellar warfare, sub-light civilizations are simply crushed.

In a conflict across star systems several light-years apart, a sub-light civilization would only be seeing images of the enemy from years ago.

Just like how the stars we see from Earth are often light emitted tens, hundreds, or even hundreds of thousands of years ago.

Because their sensors and targeting systems also cannot exceed the speed of light.

Even firing the fastest energy weapons would take years to actually reach the enemy.

To actually hit the target, you’d have to pray the enemy just stands there without moving.

From the perspective of a faster-than-light civilization, everything happening in the universe is perceived in real-time.

Even the faintest ripple hundreds of light-years away can be instantly detected.

And any attack launched would strike instantly, leaving no reaction time.

Under such immense information and technological disparities, a sub-light civilization is no better than a tribe of primitives in the eyes of an FTL civilization.

Thankfully, with Kayo Senju and Setsuna’s support, everyone would soon shed their primitive, sub-light status.

”Hiss, so we’ve finally touched the threshold of the interstellar era...”

...

After inspecting operations across the Starbase and handing over his ship to the Bulins for retrofitting, Setsuna sat in the top hall of the main building, gazing at the distant stars while contemplating the next phase of interstellar expansion.

With faster-than-light technology, the range of activity had massively increased—entire galaxies could now be developed.

”We’ll need to build a lot more Bulins and Angeloids...”

”If we’re expanding on a galactic scale, we’ll need at least a billion Bulins and Angeloids...”

”Does that mean we’re becoming a full-fledged synthetic empire?!”

While deep in thought, the system notification suddenly popped up.

[Congratulations, Host. You have completed FTL technology, advancing your civilization to a new era.]

Shua —

The statistical interface opened before him.

[Civilization Overview]

• Civilization Type: Technological Civilization

• Technological Level: Space Age (FTL)

• Population: 18.753 million

• Species: ...

Still a Space Age civilization, but now upgraded from sub-light to faster-than-light.

The list of species had also expanded—demons, vampires, Doppelgängers, and others—recruited from the Overlord world.

Then—

More prompts appeared.

[Civilization Era Upgraded]

[You may now observe more civilizations on the Hyperdimensional Starmap.]

”...”

Shua —

The hyperdimensional starmap opened once more.

The first time Setsuna set out into space with his crew, the system had rewarded him by marking several nearby neighbors.

Now, with a technological era upgrade, more had appeared.

Perfect timing—he had already conquered most of the previously discovered worlds, saving him the effort of manually exploring for new ones.

Setsuna looked at the starmap, where several new world bubbles appeared slightly farther out.

[Kantai Collection (Pre-Space Era)]

[Puella Magi Madoka Magica (Space Age)]

[KonoSuba (Tier-III Magic Age)]

[Three-Body Problem (Space Age)]

[Uma Musume: Pretty Derby (Pre-Space Era)]

”???”

”Huh???”

”What is this?!”

Setsuna nearly spit out his drink.

The newly discovered worlds this time were quite odd.

Back when Elma suggested summoning a deity to the capital, he had vaguely seen the Madoka Magica world.

The power system over there was extremely exaggerated—if Madoka became a god, it might even be classified as a higher-level magic civilization, or even a hybrid one.

Conquering the Madoka world would be a classic underdog challenge. Madoka was undoubtedly the key point, requiring careful planning and execution.

Then there was Kantai Collection...

Setsuna paused. Well, that was the original shipgirl franchise.

He already had Azur Lane shipgirls, Arpeggio shipgirls, and Siren girls.

Adding a few KanColle shipgirls wouldn’t hurt.

KanColle’s overall power wasn’t too absurd. Their enemies—the Abyssal Fleet—were more about brute strength than any magical nonsense, unlike the Azur Lane meta.

”The umbrella lady, poi, and... Northern Princess?!”

Setsuna suddenly thought of bringing over a few Battleship-class Princesses.

They were also shipgirls—representing naval base personifications.

In the future, they could be refitted into Titans and stored in starships, launched during battle like mobile Starbases.

Guaranteed to beat the enemy until they wet themselves.

Uma Musume was just a peaceful slice-of-life world. Nothing much to say.

Bringing them over to organize horse races at the base could be quite fun.

He could even give them a round of gene ascension to showcase the power of biological science.

That left two worlds:

KonoSuba and the Three-Body Problem.

The former was a classic sword-and-magic isekai.

When choosing a guardian deity for the base, Setsuna had briefly considered Aqua.

But the problem was that airhead goddess didn’t seem particularly powerful.

—Completely incomparable to Madoka.

Besides, appointing her as guardian deity might lower the IQ of the science lolis in the base.

As for the Three-Body world...

Now that he had unlocked FTL tech, the native civilization there felt a bit awkward.

They were a space-faring civilization, yet Three-Body tech was strictly limited to sub-light speeds of tens of thousands of kilometers per second.

Even their god-tier civilizations capable of pattern-based weapons couldn’t break that speed barrier.

Still, some of their tech was pretty flashy—like dimensional reduction weapons and low-speed black domains.

Dimensional srikes were great for wiping out low-level civilizations—clean and efficient.

Just don’t use them in your own universe.

Overall, this new batch of neighbors had wildly varying power levels.

Some were peaceful everyday worlds, others extreme and unreasonable magic realms.

Rather than full conquest, some of these worlds might be better approached by altering or participating in their storylines.

”Everyone, assemble!”

”We’ve got more neighbors now!”

...

A few hours later—

Inside the main building of the Starbase, all the shipgirls, Spirits, Heroic Spirits, and others gathered noisily together.

The liveliest times in the base were always when the Commander discovered a new world.

Even though most had just indulged themselves in the Overlord world, they were still eager for the chance to show off in a new one.

”So, the newly discovered worlds this time are as follows.”

Setsuna projected the hyperdimensional starmap on the holographic interface.

”Kantai Collection, Three-Body Problem, Uma Musume, KonoSuba, and Puella Magi Madoka Magica.”

He briefly summarized the situation of each world, then distributed relevant data files to everyone.

”Uh... more shipgirls?! And horse girls?”

The Azur Lane and Arpeggio shipgirls exchanged puzzled looks.

They felt it was kind of a skill how the Commander could always pinpoint worlds full of moe girls from the multiverse.

There might soon be shipgirls from three different worlds living in the base.

”Commander, how do the Kantai Collection shipgirls compare to us?”

Taihou asked.

”If you’re talking combat strength... there’s really no comparison.”

Setsuna thought for a moment.

The KanColle shipgirls were literal WWII weapons—lacking both the black-tech of Arpeggio girls and the magic of Azur Lane.

Their enemies, the Abyssals, were the same—brute-force types with no magical nonsense.

Their tech level simply couldn’t compare with the other two factions.

But since they were still shipgirls, they could be brought over and transformed into starship-compatible units—boosting their strength drastically.

”Hiss, the Commander is thinking about other girls again. Disgraceful.”

Gudako squinted and cast a look of disdain.

”Wouldn’t it make the base even livelier with more shipgirls around? Besides, we could even bring Little Northern over.”

Setsuna dismissed it casually.

”Do you have some kind of obsession with shipgirls?!”

”I’ve always followed one core principle regarding shipgirls.”

Setsuna cleared his throat.

”What?”

Gudako swore she’d never heard of such a ridiculous thing.

”All the shipgirls in existence belong to me. I want to be the Commander of every shipgirl.”

”???”

Gudako, the Heroic Spirits, and the Spirits were all stunned by that declaration.

Should they say it’s exactly what they expected from the Commander?

Putting aside Azur Lane and Arpeggio shipgirls—they had already sworn loyalty.

Even the just-discovered KanColle shipgirls and Abyssals were already part of the plan before any contact.

Just thinking about the future, when there might be three versions of the same-named ship in the port, made everyone’s expressions rather complicated.

Call out ”Kongou” and three girls might show up.

One would be the goofy KanColle version, one the Azur Lane version, and one the goth-styled Arpeggio Kongou.

”Commander, Taihou is one of a kind!”

A well-endowed shipgirl immediately threw herself at him.

”Relax, relax. KanColle Taihou is a flat-chested loli—no comparison to you.”

Setsuna savored the soft sensation pressed against him.

The Azur Lane version’s proportions were indeed reassuring.

”Alright, alright. The KanColle and horse girl worlds are easier to conquer. Let’s say they’re yours.”

”What about the other worlds?”

After flirting with Taihou for a while, Gudako brought the conversation back on track.

”The Three-Body world is perfect. It’s full of primitive sub-light era natives—their best tech barely hits lightspeed.”

”Now that we’ve completed FTL upgrades, we can head over and crush them.”

Setsuna projected that world’s info on the screen.

”Weren’t we sub-light natives not long ago...?”

Richelieu muttered quietly.

That’s how technological progress works—once you pass a certain threshold, the gap between civilizations becomes like heaven and earth.

Just like how industrial civilizations crush agricultural ones, or spacefaring civilizations overwhelm pre-space ones, a sub-light civilization stands no chance against an FTL civilization.

The group studied the Three-Body world more closely, astonished by the array of bizarre and flashy weapons.

”Dimensional strikes?! Why do I feel like that’s way fancier than any of our energy weapons?!”

”And pattern-based weapons? Mathematical laws? Physical laws? How are those even used as weapons?!”

Akashi and some of the smaller shipgirls scratched their heads in confusion, while the science lolis fell deep into thought—it looked like something had clicked for them.

”Comrade-chan, can we really beat the aliens from the Three-Body world...?”

Tashkent looked visibly worried.

”No problem.”

Setsuna rubbed her head.

”No matter how lethal dimensional strikes are, their spread rate is still capped at the speed of light—they’ll never catch up to us.”

”As long as they’re not thrown into our managed universe, there’s nothing to worry about.”

As for the survival of the Three-Body civilization, Setsuna wasn’t particularly concerned.

That universe was already riddled with dimensional collapse. The entire world might collapse into two dimensions at any time.

All they needed to do was go over, extract whatever tech they wanted, and beat up some aliens.

As for the humans of that world...

Setsuna felt it wouldn’t be wrong to call them Three-Body scoundrels.

It was hard to believe a human civilization could combine so many negative traits: bootlickers, bleeding-heart saints, anti-intellectual mobs, all rolled into one.

He had little interest in managing them.

Either ship them off to the mines to cultivate martial virtue, or just leave them be.

Finally, everyone’s attention turned to the two magic worlds.

”...Both these worlds have gods? Uh, but don’t the quality of their gods differ a little too much?”

The dragon girls and Spirits compared Madokami to Aqua.

Absurd.

There were levels to gods too.

”Isn’t the Law of Cycles a little too strong?”

Tohru and Elma stared at Kaname Madoka’s profile in amazement.

”She can influence all universes in their worldline, as well as past and future timelines, with a single thought?! That’s way beyond even a supreme god’s power!”

”Even the gods in our world can’t do that!”

”Madokami would be considered a top-tier multiverse entity. In Warhammer terms, she could drag the four Chaos Gods out of the Warp, roll them into a ball, and flush them down the Golden Throne.”

Setsuna laughed.

”But from the timeline perspective... she hasn’t become a god yet. The problem is Kyubey and the civilization behind it.”

”What we need to think about is how to deal with Kyubey.”

He glanced at the information on the Madoka world and sighed.

Letting Madoka ascend to godhood and nurturing a personal Madokami would be ideal.

But the price she paid to become the Law of Cycles was far too tragic—too heartbreaking.

If possible, Setsuna hoped to save the deceived magical girls and spare Madoka that suffering.

And find a way to eliminate Kyubey.

”Tch, it really is a tough nut to crack...”

After witnessing Madoka’s sorrowful fate, everyone made a solemn vow:

To save the magical girls and prevent the birth of tragedy—

And to let Kyubey and its civilization taste the wrath of iron-fisted justice.

...

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