Crossover Shipgirls: Building a Dimensional Empire from Scratch

”Universe No. 1 has already been handed over to the engineering department for study. The research department plans to construct two more city-level pocket-universes of similar scale for experimentation.”

”Research on law-based weapons is also proceeding in parallel. The Zero-Homer’s mathematical deduction models don’t apply under faster-than-light conditions, so new models are being built…”

”Controlled dimensional strike technology is still under testing. Observer has proposed several new experimental schemes, but the costs are high—Commander’s approval is required…”

In the administrative center, reading the sophon’s summary report, Setsuna nodded with satisfaction.

The three advanced technologies obtained from the Three-Body world were all progressing steadily.

The Bulins had created a pocket-universe, which had been handed to the research department for study. What remained was the mathematical law weapon.

This was essentially a causality weapon.

In a sense, it was also the most powerful among law-based weapons.

The Zero-Homers could use mathematical laws to deduce the development of a civilization, even the future of the entire universe.

Mastering mathematical law meant possessing the ability to invert cause and effect and foresee the future.

For Setsuna, it could likely be used in the future to deduce and manipulate the development and destiny of other worlds.

To ensure that those meant to appear would appear, and that events meant to happen would happen—without his own interference creating bugs.

It was nothing short of a divine weapon.

”Ugh… I suddenly feel like our research difficulty has increased by a whole tier.”

The nanobot sitting beside Setsuna scratched its head.

”Just researching pocket-universe tech at the starbase has those little lolis stressed enough. I still have to drop by every few days to give them a pep talk.”

”Now we’re adding law-based weapons on top of that. Sigh, looks like more overtime again.”

”How do you even encourage them? I’ve noticed Kayo Senju and the others have been very motivated.”

Setsuna was curious.

Recently, the little lolis had been working overtime at the starbase every day. Even when they occasionally came to play on the Eternal Snowfall, they still brought their work with them.

Using time distortion to squeeze out hours for work made Setsuna and the shipgirls feel ashamed while they partied.

”I told them that after finishing pocket-universe research, the Commander would marry the entire research department.”

Grey answered matter-of-factly.

”???”

Clang—

Ouch!

A fist landed squarely on her head.

”When did I ever agree to that?!”

Setsuna flicked her again, leaving the nanobot clutching its head.

”It was just to motivate them… Besides, making a universe-level pocket-universe and then stuffing it into the Eternal Snowfall is still years away, right? By then the lolis will have grown up—so it’s fine.”

”???”

”Is that the issue here?!”

Setsuna grabbed Grey’s cheeks and lifted her up. The nanobot grimaced in pain.

”Look, those lolis spend every day at the starbase far from Earth, doing research for you.”

”Give them a little something to look forward to…”

Grey argued with righteous conviction.

”But you can’t arrange marriages for the Commander!! We’re still waiting in line!!!”

Several shipgirls joined in to gang up on the nanobot.

”Commander, do we need to clear up this misunderstanding?”

Essex asked seriously.

”…”

Setsuna thought for a moment.

”No need. Clarifying it now would only discourage them.”

”And honestly, I think they’re rather cute. Just wait until they grow up.”

”Hey?! Are you seriously raising lolis now?!”

Gudako was horrified.

Ever since the Black Bullet lolis first arrived at the capital, Setsuna had been their idol.

Years had passed, and some of the more precocious lolis had already developed strange ideas about the Commander.

Led by Kayo Senju, the research lolis were the smartest and most mature group—it wasn’t surprising.

It was foreseeable that this would only become more common in the future.

After a round of noisy bickering—

Suddenly—

Shwoom—

A communication signal arrived.

The holographic interface opened before them.

”Hi, Mr. Lu, I hope we’re not disturbing you?”

Roman and Da Vinci appeared on the screen.

During the last two communications, Setsuna had been tangled up with shipgirls. This time, things were finally a bit more normal.

”Oh, Chaldea?”

Setsuna and Gudako perked up.

”Already pinpointed a new Singularity? That was quick.”

”Yes, this time it’s located in 1888, London.”

Dr. Roman nodded.

”Oh, the Fourth Singularity—Death City, London Fog. I know this one.”

Setsuna didn’t need much explanation. For the Starsea Empire, clearing a Singularity like this was nothing more than a straight push-through.

”I was planning to open a map or head to another world, but never mind. Let’s help Chaldea with this first.”

He stood and straightened his clothes.

Since he had agreed to help rebuild Human Order, there was no shirking.

”Mm… it’ll be boring to go alone. I’ll take a few with me. Who wants to come?”

As he picked companions—

Gudako tugged at his sleeve.

”Commander—no, Boss, could you give me a chance to show what I can do?”

”Huh?”

Setsuna looked at the girl with mild surprise.

”Um…”

Gudako hesitated for a bit, then lifted her head and spoke:

”Think about it. Rebuilding Human Order is supposed to be the Chaldean Master’s responsibility, right?”

”Since meeting you, for every Singularity we’ve gone to, you’ve led the way. You’re incredible. All I’ve had to do is follow and pick things up.”

”But sometimes… I want to train myself too.”

Originally, Roman and Da Vinci had entrusted her with the duty of saving Human Order.

But after Setsuna’s arrival, Chaldea and the Starsea Empire had formed a partnership.

Each time they went to a Singularity, nominally it was the two of them, but in reality Gudako was just there to shout POG.

Jeanne Alter had been recruited by Setsuna. Goetia had been defeated by Setsuna. Blackbeard and Medea Lily had also been handled by Setsuna and the Spirits.

As the official Master of Chaldea, she had very little to do with it.

Once or twice was fine, but always being the cheerleader was making Ritsuka Fujimaru feel a bit empty.

”Are you sure?”

Setsuna asked again.

”Hey! I may not be as strong as you, but I’m not that weak either, okay? Clearing a Singularity isn’t such a big deal.”

”I promise I’ll finish the mission. And the Heroic Spirits you want, I’ll bring them back for you! Not a single one will be missing!”

Gudako pouted as she spoke.

”Only the girls.”

”Ugh, obviously!!! You think I’d bring back some Berserker for you?!”

...

Half an hour later—

Setsuna, Gudako, and a few companions passed through the transfer point and arrived at Chaldea.

”So, that’s roughly the situation.”

”This time Fujimaru Ritsuka will take the lead in clearing the Fourth Singularity. I’ll provide support.”

After brief greetings, Setsuna explained the matter to Roman.

”Oh?”

Roman was a little surprised, then thought for a moment:

”Actually, that’s a good thing. As Chaldea’s Master, she can’t always live under someone else’s protection.”

Da Vinci also nodded in agreement:

”It’s not good to always rely on Mr. Setsuna either. It’s time she bore some responsibility on her own.”

”???”

Gudako felt that after years of Master absenteeism, Setsuna’s presence in Chaldea was stronger than hers.

”This Singularity isn’t complicated. There isn’t much of value to worry about—just fight through the enemies along the way.”

Setsuna gave Gudako a brief rundown of the Fourth Singularity.

Compared to the later Camelot and Babylonia, the Death World in the City of Demonic Fog was far simpler, and the story wasn’t even very convoluted.

It was indeed suitable for Gudako to train herself.

Then, he pointed at a few companions:

”Elma, Duke of York, Prince of Wales, King George V, Howe… you go with her.”

”OK.”

The dragon girl and shipgirls agreed.

”Nineteenth-century London? Perfect chance to visit. Heh…”

The George V-class shipgirls showed interest, curious to see another world’s British Empire.

”Be careful, don’t overexert yourselves.”

Da Vinci reminded them repeatedly.

”Relax. These few could crush the Trisolarans flat. A Singularity is nothing.”

Ritsuka Fujimaru’s lips twitched.

She felt the companions Setsuna had assigned were far too strong. Once again, she might just be left picking up scraps.

”Tsk, too bad those slime creatures are locked up in the zoo now. Otherwise, someday, making the Trisolarans fight the Vanguard of the Umbral Star would’ve been quite a show…”

”?”

”Wait.”

Roman and Da Vinci looked utterly baffled.

”What are Trisolarans??!”

...

[Anti-Summon System, Activate]

[Commencing Spiritron Transfer]

[Time until Spiritron Transfer begins…]

”5, 4, 3, 2, 1…”

[Process Complete!]

[Fourth Singularity: Mist City: London]

...

With the mechanical voice of the spiritron transfer system echoing—

Gudako and her team waved goodbye to Setsuna and Dr. Roman.

When they opened their eyes again—

They had landed in a city shrouded in fog.

Year 1888, London.

The architecture carried a strong period style. There were almost no pedestrians on the streets, and every building had its doors and windows shut tight.

A thick fog blanketed the city, visibility less than half a meter.

Thud—

Gudako took only a few steps before smacking her head against a lamppost.

”Tch, was 19th-century London pollution this bad?”

She rubbed her forehead, sniffled, and then realized—

This wasn’t smog from the Industrial Revolution. It was magical fog that could harm the human body.

Of course, for her, the dragon girl, and the shipgirls, it was nothing.

”Oh, so this is the anomaly of this Singularity?”

Projected into the field, Dr. Roman examined the surroundings.

”As always, you need to locate this world’s Holy Grail, then destroy or recover it.”

”That should restore things back to normal.”

”Why bother? It’s just some magic fog, right?”

Elma shook her head and stepped forward.

She raised her hand, a red magic circle appearing between her fingers.

”Clear Skies!”

Fwoosh—

A beam of light shot into the sky.

Immediately, sunlight broke through the clouds, shining down onto the streets and sweeping away the thick fog.

As a demi-god dragon girl, this was trivial for Elma.

Within minutes—

The entire city was clear.

Sunlight bathed the earth, and a rainbow stretched across the horizon.

Every trace of darkness was banished under the blazing sun.

”…”

Roman was speechless.

”Uh, so should we still follow the usual procedure, or do something else?”

Gudako looked at the shipgirls and dragon girl for input.

”Same as before—recover the Holy Grail first, then recruit Heroic Spirits.”

The Duke of York scanned the city and surrounding area, marking several points on the holographic interface.

”Oh, right. According to the Commander, Solomon will show up in the end to act cool, but he’s actually a Beast, isn’t he?”

”What should we do with him?”

Gudako suddenly remembered.

”…”

”I’ll go a few rounds with him.”

”Firepower saturation.”

The shipgirls and dragon girl gave two nearly identical answers.

”…Fine.”

”Let’s find Mordred first. Her dad’s still in the capital eating, after all.”

”Hopefully the two of them won’t fight when they meet later?!”

...

After sending Gudako off to clear the Singularity—

Setsuna returned to the administrative center.

Shwoom—

He pulled up the Hyperdimensional Star Map.

The Three-Body Problem world had been nearly fully conquered. Perhaps once dimensional and spatial technologies reached a high enough level, it would be possible to attempt a universe restart experiment there.

From the last batch of discovered worlds, two remained: KonoSuba and Puella Magi Madoka Magica.

”Hmm… Gudako left using the transfer anchor. The cooldown on spatial piercing is over.”

”Should we conquer another world now? Or scout the map first?”

He thought for a moment, then checked the map again.

It was time to find some new neighbors and spread a little love and peace.

He focused on the star map, using his mental power to disperse the fog.

Bzzt—

Since becoming a Juggernaut, his spiritual power had grown immensely.

In the past, locating ”neighbors” across the multiverse exhausted his spirit. Now, it only made him sweat a little.

Soon, four civilizations were projected on the star map:

[Shokugeki no Soma (Pre-Space Age)]

[Neon Genesis Evangelion (Pre-Space Age)]

[Re:Zero - Starting Life in Another World (Tier II Magic Age)]

[Darling in the Franxx (Space Age)]

”Oh? Four worlds detected this time? Not bad.”

Setsuna looked closely.

”Tch, all noobs…”

Two pre-space natives, one magic world, one space age.

Two of the series were already a bit old.

Shokugeki no Soma.

A cooking world.

Basically, in Japan there was an elite culinary school—Totsuki Academy. Any disputes there could be resolved through cooking battles, or shokugeki.

It also had another name—Food Wars.

The chefs’ cooking often came with special effects. At the light end, clothes exploded off people after one bite. At the heavy end, they collapsed blushing on the ground, unable to rise, like they’d just undergone a dozen IV drips.

”We could bring some chefs from that world to improve the food at our base.”

Setsuna thought it might be worth it.

These pre-space natives didn’t require him to personally go. Like with the Catgirls and Horse Girls, sending a small squad of shipgirls and Angeloids would suffice.

Shokugeki?

Sure, maybe our cooking isn’t as good. But if I deploy a starship for orbital bombardment—how will you respond, huh?!

Re:Zero.

Setsuna’s mind recalled only a few keywords:

Ram and Rem.

Apple stand.

Ah~~ my brain trembles.

It was the story of a boy transported to another world, gaining only one ability: Return by Death.

—When killed, he would respawn at a set point like in a game.

Then he kept dying and reviving, struggling desperately against enemies.

The Witch Cult Sin Archbishops’ powers were flashy, torturing Subaru endlessly.

But flashy was all they were.

Whenever Setsuna encountered a magic world, he always asked three soul questions:

Could its strongest fighter beat an Spirit or dragon girl?

Did it have means to counter FTL starships?

Could it withstand planetary bombardment or even star-crushing firepower?

If the answer to all three was no, then it posed no threat.

It could be enjoyed as a leisure world to pick up girls.

And then turned into a vassal state.

Had he encountered Re:Zero a few years earlier, it might have been troublesome.

Now…

The Royal Maid team could soon gain a few new members.

As for the other two worlds—

Setsuna’s expression turned subtle.

Neon Genesis Evangelion and Darling in the Franxx.

The latter’s name was often shortened to Franxx, but due to its high-profile production team, fans usually just called it the National Team.

Both were mecha anime.

EVA was about teenagers piloting Evangelion units—giant humanoid weapons—to battle mysterious beings known as Angels attacking Tokyo-3.

The setting was extremely complex, and the Evas weren’t even strictly mecha. Unit-01 was essentially a divine body, more like a biological entity.

Franxx told the story of humanity piloting mecha to fight monsters called klaxosaurs.

The first half of the series was solid, but the latter half… abstract beyond belief.

Still, its mecha designs were iconic. Strelizia was cool, Strelizia True Apus was even flashier, and of course, 02 was beloved.

The only catch—the mecha required a boy and girl dual pilot system, and the piloting positions were a bit… questionable. Almost like fanservice.

”Come to think of it, wasn’t Gudako recently complaining that Barbatos was too weak…?”

Setsuna remembered something.

”Shame she left too early. Otherwise, I should’ve asked her—would she rather pilot Unit-01 or Strelizia?”

”Or maybe we just mash the three mecha systems together? Hm, is there a Gurren Lagann world I can hit so I can skip straight to the top?!…”

—

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