Crossover Shipgirls: Building a Dimensional Empire from Scratch

Azur Lane Port.

After all the shipgirls and Siren girls had been moved to the Starsea Empire, this place was repurposed as something like a resort planet.

Everywhere in the port, there were massive open-air hot springs, restaurants, amusement parks, and all kinds of leisure facilities.

From time to time, shipgirls and little lolis came here for vacation.

”Buli!”

Hundreds of Bulins passed through the anchor point, landing on the open ground outside the port. They spread out their rigging and dumped a huge pile of materials onto the ground.

”We’re going to build a beacon here to provide guidance for the Arbiters’ fleet.”

”Once they break free from that parallel universe, they should be able to find this place quickly.”

Observer pulled up a holographic blueprint of a bizarre building.

It resembled a signal tower.

”Buli?”

The Bulins crowded over curiously.

”Doesn’t look too hard, buli~”

”...”

Purifier couldn’t even be bothered to ask why Bulins could read Siren schematics, so she just sent the blueprint directly to the lead Rainbow Bulin.

”Fine, you handle construction.”

”Can’t we just put it inside the capital? Isn’t it kind of weird to build this on a resort planet?”

Yukikaze poked her head out to ask.

”Please, traveling across parallel universes inside the same cosmos and crossing into macrocosmic space are two totally different things, okay?”

Observer knocked the beast-eared girl on the head with a tentacle.

”Besides, they’re more familiar with this place, so at least the coordinates won’t be off. Otherwise, they could end up drifting in outer space by mistake. Probably.”

”...”

Yukikaze, not quite understanding, stuck out her tongue.

”Free travel between parallel universes… your tech tree is seriously crooked.”

Setsuna chuckled.

Originally, he thought he’d have to personally bring the Arbiters back, but it turned out they were far more proactive than he expected.

All they needed was a beacon, and then it was just a matter of waiting.

”How long will it take them? Do we need to prepare a reception in advance?”

Richelieu asked.

”No idea.”

Purifier shrugged.

”They said once Dreamweaver finishes deconstructing their current universe and the mainframe finishes charging, they’ll depart.”

”The flow of time in each parallel universe could be totally different. It might be hours, days, even months.”

”But since they already have our coordinates, it shouldn’t take too long.”

”That works.”

Setsuna ordered some Angeloids to guard the area.

”Family should always stay together.”

...

After handling the unexpected Siren interruption, Setsuna noticed his dimensional travel skill cooldown had reset. He shifted his focus back to his remaining neighboring worlds.

Re:Zero – Starting Life in Another World, Konosuba: God’s Blessing on This Wonderful World, DARLING in the FRANXX, Neon Genesis Evangelion, and Puella Magi Madoka Magica.

”Hmm…”

”One at a time.”

Setsuna decided to continue his conquests from the simpler to the more difficult.

”Commander!!! You’re saying two of those worlds have mecha?!”

Gudako perked up with interest.

She jumped on Setsuna’s back, rocking side to side.

Her not-so-small chest rubbed against his back, bringing a soft and strange sensation.

”Yeah, uh, two mecha series.”

”EVA’s Unit-01 and the Strelizia. Classics, really.”

Setsuna replied.

”Boss! I want an upgrade for my mech!! Barbatos is outdated already!”

Gudako wrapped her arms around Setsuna’s neck from behind, pleading.

”...I mean, those two in their base forms aren’t all that strong. They’ll still need modifications…”

The Strelizia at first was limited to ground combat only.

Later, after evolving into the Strelizia True Apus form, it gained the ability to annihilate entire space fleets single-handedly, even shattering planets.

Though, its giant bridal-gown-like form was… a little weird.

”Collect them! That way we can switch around and pilot different ones!”

Gudako egged him on enthusiastically.

”C’mon, I helped you clear a Singularity and brought back so many Heroic Spirits. Can’t you get me a new mech in return?”

”I can help you clear future Singularities too! No need for you, Commander, to personally go—send me out and I’ll guarantee mission completion and bring back every Heroic Spirit you need!!!”

Bonk—

Setsuna chopped her lightly on the head.

”What’s this about ’old man’? I’m not even that old.”

”Oh, right.”

Ritsuka Fujimaru rubbed her head.

”Then those like Tohru and Hua, who’ve lived for tens of thousands of years—are they, uh, copper refining?”

”???”

Pffft—

Setsuna and the shipgirls spat out their drinks.

Smack—

The dragon girl put a hand on Ritsuka’s shoulder, a saintly smile on her face.

”I heard you’ve been learning Taixuan Eminence lately? Come, let’s spar a little…”

...

After the ruckus settled down—

In the operations lab, Setsuna projected a holographic star map and distributed data to everyone.

”This time, our target world is DARLING in the FRANXX—or you can call it Dear FRANXX or just DITF.”

This anime earned the nickname ”National Team” due to its star-studded production team. Of course, its second half’s plot didn’t quite live up to that title.

In simple terms: in the DITF world, Earth’s natives are the ”Klaxosaurs.” Tens of millions of years ago, an alien vanguard known as the VIRM invaded Earth, and the Klaxosaurs barely won.

To resist another invasion, the Klaxosaurs moved underground. Non-combatants turned themselves into magma energy, while those with combat ability paired up as Klaxosaurs.

Thousands of years later, VIRM spies infiltrated humanity’s highest organization, beginning their plan…

They directed the extraction of underground energy. The Klaxosaurs’ magma energy could produce an elixir granting humans immortality—at the cost of losing the ability to reproduce forever.

During the extraction process, to fight back against the Klaxosaurs, the VIRM guided humans to create specialized weapons—the FRANXX mechs.

Children were raised to pilot these mechs and fight the Klaxosaurs.

On the surface, it looked like humans piloting mechs to battle monstrous Klaxosaurs.

In reality, it was all part of the aliens’ plan to exterminate the Klaxosaurs and assimilate Earth.

”Uh, so we’re going to fight aliens?”

The shipgirls caught on.

In the DITF world, the apparent enemy was the Klaxosaurs, but in truth they were the original inhabitants of Earth.

Fighting aliens sounded a lot more fun than fighting little monsters on Earth.

”Yes. But beyond knowing the VIRM have infiltrated humanity’s top leadership, there’s not much more info.”

Setsuna looked over the compiled data.

”We should be able to locate their homeworld soon after arriving. Then just hit it with a Photoid or Fallen Star Lance.”

In the original story, Strelizia True Apus destroyed the VIRM homeworld at the end.

The Starsea Empire’s fleet wouldn’t need anything so convoluted. With Photoid launchers installed, blowing up a planet was about as hard as cracking an egg.

”The people and things we’re bringing back…”

Setsuna pulled up a list on the holographic interface.

”Of course we’re taking FRANXX mechs back. They’re fun, and with some modifications they’ll be useful in the future.”

”As for people… by now I probably don’t need to explain. Best to bring the Princess of Klaxosaurs too, hm.”

”...”

Everyone was already used to Setsuna’s style—take the girls, turn the world into a vassal.

Hearing they’d get to beat up aliens, they eagerly volunteered.

”Commander! Take me!! Take me!!!”

A group of destroyer shipgirls raised their hands, clamoring.

”Alright, everyone can come.”

Setsuna cleared his throat.

”Pack your gear. We’re departing!”

”I’m gonna pilot Strelizia with 02.”

”Wait!”

Gudako’s eyes widened.

”Why you with her?! I was here first!!!”

”Uh… I could make you a Delphinium instead?”

Setsuna thought about it. Technically, 02’s Klaxosaur bloodline gave her the highest compatibility with Strelizia.

”???”

”Delphinium? That’s Ichigo’s unit?! Commander, you strawberry-hearted traitor!!!”

...

A few days later—

Early morning, on the open ground outside the capital.

The girls joining the expedition lined up in several neat groups, chattering excitedly, their faces filled with anticipation.

Since this was a purely sci-fi world, and Fu Hua was still teaching Kanae and the others Taixuan Eminence, this expedition mainly consisted of shipgirls—plus Gudako, eager to see mechs, and Griseo, who habitually stayed close to Setsuna.

”Commander, I want to see other worlds.”

Little Griseo was still wearing her white dress, carrying her sketchboard. She stood at Setsuna’s side, gently tugging his sleeve, her voice ethereal.

”Of course.”

Setsuna rubbed her head.

This quiet loli rarely spoke or interacted with anyone. Bringing her along so she could spend more time with him wasn’t a bad idea.

Shua—

Setsuna pulled up the multidimensional star map, casually scanning the destination.

[DARLING in the FRANXX (Space Age)]

In this world, humanity was roughly at the pre-spacefaring stage, without interplanetary travel capability.

However, there existed an advanced alien civilization with a significantly higher level of technology. The world also possessed certain unique sciences.

[Comparison of Strengths]

Technological Level: Like an Ant.

Military Strength: Like an Ant.

Economic Power: Like an Ant.

...

Just as expected—

In the DITF world, humanity had managed only to build a few mechs, still struggling on the surface against the Klaxosaurs.

Meanwhile, the alien VIRM were far more advanced, able later to deploy a sizeable space fleet to invade the solar system.

But…

”Three ratings of ’Ant.’ Advantage: ours!”

”Open the door—Starsea brings the warmth!”

Hum—

With a wave of his hand:

[Spacetime Corridor Established]

[Constantinople → DARLING in the FRANXX]

The air rippled in the distance, space twisting open into a massive shimmering corridor.

Shua—

The shipgirls projected their hulls one by one.

The fleet slipped into formation, warships crossing the corridor and vanishing in a flash of brilliant light.

...

DITF World.

After the dazzling kaleidoscope of transition—

A strange planet appeared below the fleet.

For convenience, Setsuna was traveling aboard one of the shipgirls’ bodies this time.

The Eternal Snowfall would only be projected if absolutely necessary.

”Commander, is that really Earth down there?”

”Mm… looks nothing like ours…”

Aurora pointed downward.

Unlike the thriving capital—or any Earth from the other worlds—

From high altitude, this Earth appeared a vast expanse of ochre brown.

The surface was covered in deserts, abandoned structures, and massive extraction devices resembling oil rigs.

The Eurasian continent, even the tropical rainforests of South America, had all become barren wastelands.

The only visible human settlements were fortress-like cities scattered across the wilderness.

Each was relatively small, encircled by towering metallic walls.

Gun turrets, missile launchers, and all manner of weaponry lined the battlements, guarding against outside threats.

Inside, the cities resembled pre-space age architecture, though far more sparse.

Some were built like plantations, protected under transparent domes.

”Whoa… the environment’s awful…”

Gudako leaned over for a look.

”The population here doesn’t even add up to a hundred million, huh? Less than our world’s total. Tch.”

”Eternal life does that.”

Setsuna replied.

In the DITF world, long ago, humanity discovered that magma energy deep underground contained a substance that could be refined into an immortality drug.

This drug could halt aging completely, granting eternal life—at the cost of losing the ability to reproduce.

For ordinary people, the temptation of immortality far outweighed that of reproduction.

And so, to produce more of the immortality drug, humanity began large-scale extraction of underground magma energy, causing severe environmental devastation.

Over-exploitation of magma energy also sparked war between the underground Klaxosaurs and humans.

One thing led to another, and most of the world’s cities were reduced to ruins.

The remnants of humanity could only cling to survival within fortress cities.

”Uh, Commander, what should we do about Earth here in this world?”

Aurora suddenly voiced a not-so-small concern.

This Earth was already nearly ruined by the native humans of DITF. Even if they became a vassal, there wouldn’t be much in terms of resources left to extract.

”There’s still the solar system, the galaxy. These people just happen to all be immortal—perfect labor stock.”

Setsuna snorted.

”They like mining? Fine, send them to dig on other planets. They won’t age or die anyway, they can work for a lifetime. Perfect.”

”...That’s actually a damn good point.”

Human Evil nodded repeatedly.

”Alright then, scan this planet, conquer them, grab the people we need, and then we’ll deal with the aliens.”

At his order—

The fleet split into groups, engines roaring as they streaked off into the distance.

Beep—

Aurora also activated her sensors, scanning the fortress cities below in detail.

Soon, the ship’s AI gave a report.

”Target found: 332 kilometers due north.”

...

...

City No. 13.

Within a transparent dome.

Unlike the barren lands outside, inside was filled with birdsong, forests, meadows, and artificial lakes.

In the woods stood a villa-like building, home to a group of young children and the uniformed adults who cared for them.

This was the residence of FRANXX pilots. From childhood, they were raised to pilot mechs. Officially, it was called ”Mistletoe.”

But it had a more fitting name—”The Birdcage.”

The children, aside from daily training, were forbidden from leaving the dome. They knew nothing of the outside world or the skies above.

Their mission was simply endless training—piloting FRANXX mechs to battle the Klaxosaurs.

They believed this to be their sole purpose in life.

Huff—huff—huff—

In the forest—

A small girl in a black cloak ran desperately, her skin tinged red, forehead adorned with two long horns. Pink hair, green eyes.

She stumbled clumsily deeper into the woods.

Behind her, not far away, uniformed soldiers in full gear gave chase.

”All units, attention! Experimental Subject 02 has just escaped!”

”She cannot escape the Birdcage, she should be nearby. Find her!”

”Attention: she is vital experimental material. Do not use lethal weapons. Bring her back to the lab safely, at all costs!”

Orders from above crackled through their comms.

The soldiers leveled their weapons, switching on spotlights.

They began sweeping the forest in a carpet search, following 02’s tracks.

”Ugh!”

Sensing pursuit, the little loli ran harder.

She dashed frantically through the trees, trying to evade the soldiers.

But—

Thud—

She slipped on a stone, tumbling to the ground, rolling several times.

”Mm…”

Blue blood flowed from a cut on her leg.

The sharp pain forced a whimper from her lips.

”There!”

The soldiers locked onto the sound.

Instantly, spotlights and laser sights converged.

The loli tried to get up, but her injured leg gave out. She could only sit, baring her teeth in a fierce expression, hoping to scare them off.

But she instinctively backed up, scooting until her back pressed against a tree.

Trapped in a dead end.

”Target found. Prepare for retrieval.”

Clack—

The soldiers switched to tranquilizer rounds, loading and aiming.

Just as they were about to fire—

Boom!

Crash—

Glass shattered overhead.

A starship’s kinetic cannon tore through the dome, and sunlight vanished beneath the shadow of a massive warship.

Then came the cold, mechanical voice of the fleet AI:

”Target located. Deploy Angeloids. Retrieve 02. Eliminate all hostile units. Secure the city.”

—

—

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