Crossover Shipgirls: Building a Dimensional Empire from Scratch

About two months later.

A massive fleet departed from the stellar base.

At the forefront was none other than the Eternal Snowfall, now refitted with a faster-than-light engine.

Following closely behind were several hundred starship shipgirls.

Since this was an informal refit focused mainly on adding FTL drives, communication systems, and some experimental weaponry, the shipgirls' appearances hadn't changed as drastically as before—just a bit larger in size, and their mounted weapons had some minor differences.

Inside the bridge, Lucoa, Tohru, and Elma—the three dragon girls—gathered together. Just in case, Setsuna had brought along the usually reclusive library-dwelling elder dragon girl.

Vmm—Boom—

Upon entering faster-than-light travel, Lucoa looked out the porthole at the bizarre, dazzling scenery with mild astonishment.

"Have I been holed up in the library too long? Why does it feel like I can't keep up with the times anymore?"

"Little Setsuna, what exactly are you all doing?!"

Lucoa usually wore a carefree, smiling expression, giving off the impression that everything was under her control. But the FTL starships had exceeded even her expectations.

"I remember your '617' unit could barely manage atmospheric flight before, right?"

"That was ages ago, come on!"

The shipgirls quickly realized that Lucoa's sense of time was rather strange.

Which made sense—after all, she was the type to casually talk about taking a 2,000-year vacation in the capital.

The elder dragon girl had spent all her time in the library training Nia Honjo, occasionally teaching Kanae, Gudako, and others in magic, but rarely interacting with Setsuna.

This was also her first time participating in an away mission.

"Incredible, incredible..."

Lucoa marveled repeatedly as she watched the fleet maneuver swiftly across thousands of light-years of space.

"In our world, even for demigods—no, even for gods—jumping across space on this scale would be extremely difficult."

Teleporting on a planetary surface was something a stronger mage could handle.

Tohru and Elma could open portals to appear anywhere on Earth.

But maneuvering across thousands of light-years in space was a different matter entirely.

"Faster-than-light travel is indeed a high-level technology, even for a technological civilization. Compared to magical civilizations, it's certainly on par."

Setsuna replied with a smile.

Beyond just speed, FTL also brought with it instantaneous information processing and strike capabilities—both critically important.

Vmm... Boom!

From the solar system to the L-Gate system—Kepler-160—was a distance of 3,000 light-years.

The fleet underwent multiple long-distance, long-duration hyperspace jumps.

After another period of travel, and following their final exit from hyperspace...

A completely unfamiliar star system came into view.

It consisted of a red giant and several orbiting planets. The star, many times larger than the sun, radiated intense heat, scorching the lava worlds closest to it.

Further out, gas giants and frozen worlds orbited in silence.

In most ways, it looked no different from any other planetary system in the universe:

Desolate, lonely, and without any signs of organic life.

The only anomaly was a celestial object slightly larger than Earth, situated just beyond the star's gravity well.

Upon closer observation, the L-Gate was enormous. Rather than a gate, it resembled a planetary-sized glowing sphere.

The ships detected no gravity from it. Thanks to the advanced technology of its creators, the L-Gate showed almost no interaction with the surrounding space.

Several research vessels hovered nearby, conducting scans and analysis.

"We've determined the L-Gate is anchored in this space."

Kayo Senju reported.

"Its relative position doesn't shift due to the star or planetary rotations, nor is it affected by any gravitational force. It's as if it's been nailed in place."

"Oh?"

Setsuna's interest was piqued.

All celestial bodies—planets, stars, even the entire galaxy—are in constant, albeit slow, motion and rotation.

The L-Gate being anchored at a fixed location indicated just how stable its existence was, and how ridiculously advanced its creators must have been.

"Won't it crash into one of the orbiting planets then?"

Gudako asked curiously.

"The materials used to construct the L-Gate are incredibly strong and possess powerful self-repair capabilities. I suspect it could even survive falling into a star."

Kayo Senju pulled up a large batch of reports on the screen.

They found that unless struck with ultra-high-power energy weapons, conventional probe lasers had no effect whatsoever.

Even when it did sustain damage, the affected area regenerated visibly in real time.

She really wanted to study this material. If it could be applied to their own buildings or ship hulls, it would mark a massive leap in materials science.

As they spoke, the group arrived in front of the L-Gate, gazing up at the towering megastructure.

"The Stargate is currently in a sealed state. Its teleportation function has been manually disabled."

"Based on analysis from the research ships, to fully activate it, we need to find seven different L-Gates and perform a comparative analysis."

A loli scientist responsible for the data analysis reported.

This aligned with the standard Stellaris setting: seven clues were required to unlock the L-Gate.

"Huh? Are we hunting for Dragon Balls now?!"

"Even finding one was pure luck. How are we supposed to find seven in this vast universe?!"

Gudako was visibly displeased.

Searching for L-Gates in the galaxy was like looking for a needle in a haystack. If they were scattered across distant superclusters, it would be even worse.

"Which is why we need to try a different method."

Setsuna had anticipated this. He snapped his fingers, and the side hatch opened.

"Open the gate—release the Bulins."

Bruin!!

Thousands of Specialized Bulin units descended in shuttles, landing above the L-Gate.

They pulled out their Meow Meow Hammers and began working furiously.

"Can you help me open the L-Gate?"

Setsuna asked.

"..."

The lead Specialized Bulin scratched her head.

"Bulin doesn't know. Bulin's never seen this before. Bulin will take a look."

"Alright."

It was the first time a Bulin had given such an uncertain response.

Usually they would say "Bulin thinks it's doable" or "That's outside Bulin's jurisdiction."

Clearly, the L-Gate was no ordinary task.

Bang—Bang—Bang!

The Bulin army worked at a dizzying speed atop the L-Gate.

Accompanying loli scientists brought their instruments to assist in the decryption.

Setsuna simply waited aboard the Eternal Snowfall.

If the Bulins couldn't manage, he was prepared to let Lucoa or Mio give it a try.

There were plenty of magic users in the fleet—they were bound to come up with something.

...

A few days later.

As everyone passed the time stargazing in boredom—

Clang—

With a final strike from the Meow Meow Hammer, Specialized Bulin completed her work, and the space around them violently trembled.

Though there should be no sound in a vacuum, Setsuna could almost hear a thunderous roar.

Vmm—

The L-Gate suddenly emitted a blinding, star-like burst of light, nearly dazzling the shipgirls watching from the bridge.

Next, the mechanical upper and lower sections of the Stargate began to slowly rotate, and the outer devices lit up with a faint green glow.

This megastructure, sealed for who knows how many worlds, had been activated.

"Success!"

Specialized Bulin waved her Meow Meow Hammer in celebration.

Immediately, a powerful pulse signal radiated from the L-Gate, sweeping across more than half the galaxy.

At the same time, the Eternal Snowfall and all nearby shipgirls received a strange transmission—a garbled message projected on the main control screen.

The message was written in an ancient alien language. However, the creators had thoughtfully included a translation template for future interpreters.

AI 5.8 quickly parsed the message:

"Greetings, unknown civilization."

"We are the creators of the L-Gates, hailing from a galaxy billions of light-years away. Our names are not important."

"Eons ago, we developed a form of nanotechnology capable of self-replication and evolution. We named it the 'Grey Tempest.' It was our crowning achievement in engineering and physics."

"The nanobots could replicate without limit and enhance themselves by learning from external data—the perfect tools and ultimate war machines."

"But over time, our relationship with the nanobots deteriorated. Eventually, it led to a full-scale war."

"No one could resist the Grey Tempest. Our civilization was wiped out."

"To prevent disaster from spreading to the galaxy and beyond, we used our last strength to seal the L-Gates. Please do not activate them again."

"The Grey Tempest will bring catastrophe to all worlds."

...

"Huh?!"

When the message from the L-Gate was deciphered, everyone present was startled.

"'Grey Tempest'?! That sounds like a natural disaster!"

"The creators of the L-Gate were a super civilization, right? And they were wiped out by the AI they created?!"

Yat Sen looked at Setsuna with concern.

"Commander, are we really going to open the L-Gate?"

"What if whatever's inside is hostile..."

Just as Setsuna was considering whether to summon another fleet from home or return to base to regroup,

Lucoa spoke up.

The elder dragon girl, usually carefree, now wore an uncharacteristically serious expression.

"Let's do it."

"I want to see what this so-called 'crowning achievement of engineering and physics' really is."

She was intrigued by the message left behind inside the L-Gate.

Apparently, the civilization beyond the gate had created some incredible technological marvel that ultimately spiraled out of control and destroyed them.

Lucoa was eager to meet this so-called 'Grey Tempest' that had wiped out its own creators and could supposedly sweep across an entire galaxy.

Tohru, Elma, and Mio were also eager to go.

"I must uphold peace in the universe and all worlds. Anyone attempting destruction will be brought to justice."

Elma pulled out her trident and struck a battle-ready pose.

"Wipe out an entire galaxy? Sounds like she might be even better at planetary destruction than we are?!"

Tohru suddenly felt she might get along well with the Grey Tempest.

They might even be besties on the chaos alignment side.

Vmm—

As they spoke, the L-Gate fully activated amidst spatial tremors.

From within the black hole-like structure, strange and dazzling visions refracted outward.

On the other side lay the former home system of the creators—the L Cluster.

The L Cluster had no hyperspace lanes connected to the Milky Way and was located who-knows-how-many million light-years away.

"All units ready!"

At Setsuna's command, the shipgirls prepared for combat.

They waited for several hours, but nothing emerged from the Stargate—no hostile ships, no activity at all.

Everyone breathed a small sigh of relief.

"Looks like it's not a Grey Goo fleet. Let's move."

Setsuna was quite familiar with the nature of the L-Gate.

The Eternal Snowfall took the lead and entered first.

The moment its hull touched the celestial object, a flash of blinding white light enveloped it, and it vanished into the starry void.

When they opened their eyes again...

They found themselves in an unfamiliar star system.

Directly ahead was a colossal celestial body at the center of the system.

A black hole over a hundred astronomical units in diameter—its accretion disk stretched outward for billions of kilometers, past the orbital paths of planets.

Unlike the typical impression of pure darkness, interstellar matter drawn into the black hole underwent compression and friction, releasing immense light and heat.

From afar, it looked as if the black hole wore a halo.

"It's magnificent..."

Seeing one of the universe's most terrifying and mysterious celestial bodies up close, the shipgirls were momentarily dazed.

Outside the black hole's gravitational influence, several scattered planets still orbited.

Most of them were severely damaged, as if ravaged by external force—even their planetary cores were exposed.

As the fleet skimmed over their surfaces, traces of ruined structures could be seen, along with a thin layer of gray dust blanketing the terrain.

"This was the battlefield between the 'Grey Tempest' and its creators."

Setsuna gave it a quick scan.

Both sides had employed planet-destroying weapons. High-energy rays had shattered entire worlds, and wreckage from starships still drifted through space.

He even suspected the massive object at the system's center had once been a star—collapsed into a black hole during the war.

After all, no sane civilization would choose to settle right next to a black hole.

The intensity of the conflict was beyond imagination.

"Hiss..."

The shipgirls and dragon girls were all on high alert, fearing they might encounter the rumored "Grey Tempest."

The Spirits and Heroic Spirits could do little more than brace themselves—they quickly realized how powerless they were in the face of a true cosmic calamity.

Destroy a star? A galaxy? An advanced, space-age civilization?

Most of them couldn't even destroy a single planet.

The fleet patrolled the L Cluster.

Every stellar system here had been devastated. Finding a single intact planet was nearly impossible.

The creators had been annihilated thoroughly, leaving no survivors and not even a single intact starship.

The Bulins collected samples of the gray substance coating the surfaces of planets—those were the remains of dead nanobots, like dust and silt.

Given their current level of technology, they still struggled to analyze the nanobots' structure.

The more they saw, the more uneasy the shipgirls became.

Lucoa had her eyes narrowed the entire time, her expression unusually serious, as if she were simulating in her mind what kind of war could possibly result in this level of destruction.

The scale of interstellar warfare here far exceeded anything she had seen in the Dragon Maid world.

"It's a relief there are no enemies in the cluster..."

Aurora patted her cheeks and let out a soft sigh.

"But there's nothing of value here either. All we can do is slowly excavate the ruins..."

The lolis were disappointed and wanted to dispatch a few research ships for exploration.

Suddenly—

"Alert! Alert!"

"Massive spatial disturbance detected ahead!"

"Unknown warship approaching!"

A flood of alarms blared from the AI.

At the far end of the star system, space tore open violently.

A colossal warship, larger than the Eternal Snowfall, appeared—its entire hull a dark green, covered in etched dark patterns.

Its shape and structure were unlike any known ship class. Its design looked incredibly futuristic.

"Enemy contact!!!"

Clack-clack-clack—

The tense shipgirls immediately turned toward the unknown ship, activating all weapon modules. Corrosive missiles locked on, ready to fire.

Appearing here in the L Cluster, who else could it be but the Grey Tempest?

However, seeing that it was only one ship—and not a swarm of apocalyptic warships—many breathed a slight sigh of relief.

Lucoa raised her hand to cast a spell, then hesitated and canceled it, choosing instead to observe.

"Hold fire."

Setsuna saw that the enemy ship showed no hostility and signaled the girls to stand down.

"Who are you?"

Richelieu frowned.

"Wow, starting a fight the moment we meet? Humans sure are unfriendly."

A strange signal suddenly came through.

The unknown entity had, in an instant, cracked the fleet's encrypted communication.

From the voice, it sounded like a playful young woman.

"Humans? Don't tell me you're human too?"

Richelieu raised an eyebrow.

"Uh..."

"Then maybe I should change my form?"

The dark green warship emitted a plume of gray mist.

Before their eyes, it began to twist and reshape as its nanobots reconfigured.

First, it compressed into a mass of gray nanites.

Then, the nanite mass gradually took on a humanoid shape—

Limbs, a head, clothing...

A few minutes later—

A silver-haired, blue-eyed girl appeared in the void, wearing an outfit somewhat reminiscent of the fleet's uniforms.

She had a charming face, an alluring figure, and a playful air about her.

Despite floating in outer space, she seemed completely unaffected by the vacuum. Her long hair billowed gently behind her.

She walked forward in the void, heading toward the Eternal Snowfall.

With each step, a wave of gray mist trailed behind her as if she were teleporting.

In just five or six steps, she crossed tens of thousands of kilometers and landed directly on the bridge of the Eternal Snowfall.

She raised her hand and knocked on Setsuna's door.

"Hi, my dear Commander. Do you want to mate with me?"

"Uh, my sleep cycle is coming up, so could you hurry, please?"

"???"

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