Crossover Shipgirls: Building a Dimensional Empire from Scratch

A few days later—

Solar System Starbase.

On the main platform in front of the central structure, a massive signal transmitter had been erected, the size of a battleship.

The signal tower was entirely forged from black metal, resembling the transmission towers on Earth but with a far more futuristic design.

It was enormous—standing below, one could hardly see its top.

Inside the control room, the loli researchers tapped rapidly on the holographic interface.

A crowd of shipgirls gathered to watch, even Purifier, Observer, and the others who were busy with dimensional technology research came over.

Everyone wanted to witness contact with the true god-level civilization of the Trisolaran universe—the Zero-Homers.

”Done.”

”With stellar reflection, this tower can broadcast tachyon signals across the entire Milky Way at FTL speed.”

”If the other side’s technological level is high enough, they will be able to receive our message.”

Kayo Senju ran a full self-check on the equipment. After confirming no issues, she exhaled in relief.

Though tachyon sensors were already used frequently on starships, broadcasting across the whole galaxy was a first.

For the Bulins, it was simply building it on a larger scale—not difficult.

”Comrade-chan, after we send the broadcast, won’t we risk exposing our position to a Dark Forest strike?”

Tashkent asked casually.

”Impossible. Any civilization capable of receiving the signal will immediately recognize the technological gap.”

The little loli was brimming with confidence.

”They won’t be able to trace tachyon origins, only passively receive the message. Our information warfare is simply not on the same level as theirs.”

She explained some technical details that went over Setsuna and the shipgirls’ heads.

But since the researchers, the Bulins, and Grey all confirmed it was safe, then it was safe.

Soon, the broadcast was initiated.

”We’ll transmit the message in three segments.”

”The first is a self-decoding linguistic system, ensuring aliens can understand our language and basic situation. Humanity already has one—it’s the same type we sent to the Trisolarans.”

The little loli input a string of complex characters into the console.

”The second is a greeting, to show we have no immediate hostile intent. After all, FTL civilizations can be frightening to others.”

”The third is an invitation to meet the Zero-Homers. Out of curiosity, they might be willing to respond.”

”Since they’re a god-level civilization here, they should have methods to contact us.”

Setsuna nodded, finding nothing wrong with the plan.

The Zero-Homers were used to roaming around creating death lines. In such a vast galaxy, it shouldn’t be hard to run into a few individuals.

”Proceed.”

Buzzz—

The signal tower activated.

A deep hum resonated, and invisible tachyon signals burst forth from the Solar System, spreading across the Milky Way at FTL speed.

To native civilizations, and those that had only just entered the space age with primitive lightspeed ships, the broadcast was incomprehensible.

They merely sensed garbled noise, dismissing it as cosmic microwave background distortion and discarding it.

Only civilizations at far higher levels than the Singer’s could parse even fragments of the content.

Quite a few civilizations were shaken by the FTL signal, trembling as they scrambled to hide their existence.

...

After the broadcast finished—

Grey stood eagerly at the starbase’s docks, stretching her limbs.

”Hmm, just relying on broadcasts is too slow. Let me move around a bit.”

”If the Zero-Homers get spooked and hide, I can just drag them out.”

”???”

The shipgirls were stunned.

”Find them? How? The galaxy is massive. Even our entire fleet wouldn’t be enough!”

”I alone am an army. Don’t forget who I am.”

The nanobot girl puffed her chest.

”Speaking of which… I haven’t eaten in a while. Let’s see what the civilizations of this universe taste like.”

With that, the girl in the black military uniform stepped to the edge of the starbase, then leapt into the starry void.

Shwoom—

Her body dissolved into a vast grey nanocloud.

The nanocloud condensed in the distance into a strange starship, glowing faintly dark green.

Under an ultra-high-magnification microscope, one could see that this vessel was actually composed of countless nanobots.

Crack—

Then, the nanostarship split.

Like cellular division, one ship became two identical ships.

Then two became four, four became eight…

The Gray Tempest possessed infinite self-replication and the ability to draw energy from the void.

Together, these formed a terrifying combination.

In the past, the Creator had sealed Grey within the L-Gate at the cost of his life, fearing she would bring a galactic-scale crisis.

”Ah…”

The shipgirls were dumbfounded at the sight of Grey’s ”Gray Tempest” form.

In just minutes, under exponential growth, the nanostarships filled the stellar orbit.

They formed neat phalanxes, arrayed from high above the sun all the way out to Saturn’s orbit.

Looking up from Earth, the natives saw the sky covered entirely with ships stretching from one horizon to the other.

People on the streets nearly collapsed in terror, some almost crying.

”So this is Grey’s true body?!!”

The Sirens, shipgirls, and loli researchers were all stunned.

”Mhm~”

”Commander, I’m heading out!”

The girl’s cheerful voice rang out over comms.

”Watch me dig three feet into the ground if I have to—I’ll find the Zero-Homers!”

Shwoom—

An uncountable number of starships split into tens of thousands of squadrons, scattering in every direction across the stars.

Even as they flew, they continued replicating and dividing.

After only a few interstellar jumps, the number of fleets had multiplied several times over.

From a distant astronomical scale, the entire galaxy seemed shrouded in a grey stormcloud. Only close up could one see that it was made of countless nanostarships.

Gray Tempest—her name was no exaggeration.

She was a storm capable of sweeping across the galaxy.

”Sub-light natives challenging a Stellaris-level crisis. Overkill. Good luck to you all.”

Setsuna clapped his hands.

”My wife is really strong.”

”…Wait a minute. So this whole time she’s been slacking off?!”

...

The civilizations of the Trisolaran galaxy felt like they were witnessing a nightmare.

Endless nanostarships, like a natural disaster, flooded across the galaxy.

They activated FTL drives and sensors, pouncing on every civilization and fleet they detected.

Resistance was futile.

The nanostarships were endless—destroy one, two more would split off.

The firepower of thousands upon thousands of ships could scour a planet’s surface clean in an instant.

Then the nanoclouds would engulf the planet, using its resources to create even more starships.

Even dual-vector foils were useless. Their FTL speed made them impossible to hit, attempting it was just suicide.

Running was hopeless too.

Sub-light natives trying to outrun an FTL crisis was nothing but a death wish.

For a time—

The galaxy was filled with wails.

The more advanced civilizations cranked their lightspeed engines to maximum, sealing themselves into low-light-speed dark domains.

This was the ultimate ”cosmic safety statement”—inside, no one could leave, and outsiders couldn’t detect them.

Even then, the nanofleets didn’t care.

They activated jump drives, forcing their way inside, leaving the natives sobbing in despair.

”….”

”….”

Given that nearly no one in this universe could oppose Grey—

Setsuna remained at the starbase with the research teams, focusing on controllable dimensional reduction weapons.

The Fallen Star Lance was already near the peak of conventional weaponry. The Starsea Empire’s next step, like all god-level civilizations—

—was to understand the laws, and command the laws.

Finally—

About a month later.

While Setsuna was accompanying Purifier and Observer in yet another strange star system, conducting their fiftieth experiment—

A message came from Grey.

”Commander, I found the Zero-Homers.”

”I half… uh, no, I fully exchanged opinions with them. Do you want to come take a look?”

...

The Eternal Snowfall, carrying the curious shipgirls, activated her warp engine. After several consecutive jumps through the void, she emerged in an unfamiliar star system.

This place was over ten thousand light-years from the Solar System, a mysterious nebula never before explored.

Shwoom—

Following Grey’s directions, everyone rode within Aurora’s hull toward a small asteroid at the edge of the system.

”Zero-Homers!”

”What do they look like? Mammals? Cold-blooded reptiles? Or maybe birds?”

”They won’t be some kind of octopus-like Cthulhu, right?”

Yukikaze, Tai Yuan, Fu Shun, and several other little shipgirls pressed impatiently against the portholes.

They were eager to finally see the so-called god-level civilization of the Trisolaran world.

”Hmm… considering the vastness of the universe, there could exist lifeforms we’ve never even imagined before. Silicon-based life, or even gaseous life, for instance.”

Kayo Senju thought aloud.

”Also, I don’t think a civilization with a technological level bordering on infinity would still maintain its original physical form.”

”Their mode of existence is probably something beyond our imagination.”

The scientist’s vision was far broader than that of the little shipgirls.

In the grand universe, alien beings—shaped by wildly different environments—were unlikely to resemble humanlike mammals. Even finding something vaguely animal-like was rare.

During the expedition, the shipgirls had already collected bizarre specimens for the alien zoo: besides the slime-like Trisolarans, there were mushrooms, shrubs, and even indescribably strange creatures.

Who knew what forms civilizations might evolve into under alien conditions?

”Hopefully they don’t look too disgusting, or I might end up with racial OCD.”

Setsuna cleared his throat.

If this had been one or two years ago, he might have feared the Zero-Homers.

But once they had crossed the line beyond lightspeed, so-called god-level civilizations were nothing special in his eyes.

They were merely the strongest among the natives.

At the edge of the planet, they spotted a black column of light stretching from the ground to the stars. It was about twenty to thirty meters in diameter, over a hundred kilometers long.

This was the darkest thing in the universe—the death line.

A byproduct of high-power lightspeed ships, twisting space. Within a death line, the speed of light was zero. Zero light speed meant true death—absolute death, one hundred percent.

Every fundamental particle, every quark—dead, motionless.

This was the handiwork of the Zero-Homers.

Their alliance sought to reduce light speed to zero, then restore the primordial era of infinite light speed.

”Stay clear of the death line. If it spreads, it’ll be a pain to deal with.”

Setsuna warned.

Escaping from a black domain with an FTL ship was not difficult, but inside, time would distort.

He had no desire to repeat Cheng Xin’s fate—entering and exiting a black domain only to find eighteen million years had passed outside.

Before long, the ship descended slowly from orbit, where they saw Grey waving to them from the barren asteroid below.

The surface had only a thin atmosphere, and the starry sky was visible overhead at a glance.

The nanobot girl stood beside a small alien ship, beckoning to them.

The ship was not her own hull. Its design was distinctly alien, though damaged—apparently after a fight.

But what shocked Setsuna and the shipgirls most was the being standing beside her—the one she called a ”Zero-Homer.”

”!!!”

”What the—?!”

The ship burst into chatter.

The hatch opened, and everyone rushed out, crowding around and scrutinizing the figure.

”Here, this is a member of the Zero-Homers Alliance.”

”When I found him, this guy was powering up his lightspeed ship, generating a death line at maximum output nearby. I gave him a beating.”

Grey gestured casually.

”You’re a Zero-Homer?! For real?!”

Almost simultaneously, Setsuna and the shipgirls asked the soul-deep question.

Before them stood not a bizarre fungus, shrub, or indescribable eldritch creature—

—but a human.

A perfectly standard human.

A middle-aged man in a white shirt and black trousers, tieless.

The man’s face combined both Asian and European features, yet he could never be mistaken for a local anywhere.

His features were too perfect—so perfect they felt unnatural.

He stood straight, expressionless.

”Greetings. To be precise, I am a member of the ’Zero-Homers’ Alliance.”

”There are many members within the Alliance. My civilization is only one of them.”

His voice, like his face, was impeccably standard, devoid of any distinct traits.

Clearly, he had mastered the linguistic self-decoding system they had broadcast earlier.

”You’re human? Wait, no—why do you look like that?!”

Setsuna noticed his sensors did not even register the man as a biological entity.

”My civilization has already completed pure energy conversion. Strictly speaking, I no longer possess a ’face’ or ’form.’”

The Zero-Homer replied calmly.

”I adopted this human appearance solely for ease of communication with you. Whether you accept it or not, this was my best effort.”

Pure energy conversion.

Setsuna and his companions were slightly startled.

They had shed material bodies completely, existing purely as energy beings.

It was indeed a fitting form for a god-level civilization.

”Which star system are you from?”

Observer waved her tentacle rigging as she asked.

”...”

The Zero-Homer fell silent for a moment, glancing uneasily at Grey.

”Forgive me, but I cannot answer that.”

”Why not?”

The shipgirls were even more intrigued.

”Because we fear you. In this universe, everyone—any intelligent, sentient civilization—fears you.”

”You have surpassed lightspeed, breaking the rules of the cosmos.”

The ’man’ answered in a standard tone.

”Look at you, you’ve traumatized him.”

Richelieu cast a glance at the nanobot girl.

”What?! When I found him, he was about to escape. I just intercepted him, that’s all.”

”Besides, I’ve already cleaned up the other Grey Swarms in the galaxy!”

Grey looked displeased.

Setsuna wasn’t sure how she had subdued the Zero-Homer, but clearly, he was terrified of her—terrified of revealing his homeworld’s coordinates, lest the Gray Tempest come knocking.

An FTL crisis was nightmare fuel for sub-light natives.

The nanobot girl then pointed toward Setsuna.

”This is the Commander—the leader of our Starsea Empire.”

”He wants to see you. Be honest with your answers, ahem.”

”...”

The Zero-Homer looked at Setsuna, then at the shipgirls, and finally at the Eternal Snowfall looming above.

”You’ve still kept your primitive material forms? Incredible…”

”I had assumed that as the ’gods’ of this universe, you would long ago have completed energy conversion, becoming higher lifeforms.”

”But… perhaps this is your philosophy of existence. I shouldn’t pry. My apologies.”

”...”

Setsuna had no desire to become a glowing energy orb—simply because he liked the human form. Besides, it allowed him to be intimate with his shipgirls.

A man must follow his heart.

...

A few minutes later, they skipped unnecessary pleasantries.

The Zero-Homer, deeply respectful toward an FTL overlord, spoke cautiously. The stronger a civilization was, the more they could appreciate the absurdity of the Starsea Empire—and the more they respected true power.

Unlike lesser races, they did not pick pointless fights.

Setsuna and the shipgirls, in turn, were fascinated by the Zero-Homer.

Inside a small shuttle, they listened with interest as he described his origins and civilization’s current state.

His people were ancient. Back when Earth was still forming primitive life, his civilization had already ventured into space, traveling aboard lightspeed ships.

Still, he never mentioned his home cluster, glancing at Grey with visible unease.

The Zero-Homers Alliance was in truth a coalition of civilizations sharing the same goal: resetting the universe.

Their purpose was simple—reduce the universe to zero dimensions, then cycle it back up through ten dimensions, recreating the idyllic ancient era.

In a ten-dimensional universe, light speed was infinite—even faster than the Eternal Snowfall’s warp engines.

A being could cross from one end of the universe to the other within a single Planck time.

And time itself had multiple dimensions.

That meant one could make two completely different choices simultaneously.

Even after making a decision, one could ”go back” and undo it.

It was a dreamlike cosmos. Just hearing the description made the shipgirls yearn for it.

Of course, joining the Zero-Homers Alliance had requirements.

Every member civilization was what one would call a ”god-tier civilization.”

At minimum, they possessed the ability to generate death lines with high-output lightspeed ships, and generally wielded the power to manipulate cosmic laws or unleash dimensional reduction strikes.

”So many civilizations… how did they all independently come to the same idea?”

Richelieu asked curiously.

For her, it seemed incredible that countless advanced civilizations could share such identical goals. After all, Trisolarans, Singers, and Humans—three vastly different societies—could never agree on anything.

Whenever they met, it was war to the death.

”Any civilization that masters the Mathematical Laws will inevitably do the same as us—join the Zero-Homers Alliance.”

The Zero-Homer replied.

”Wait a second!”

”What did you say? Mathematical Laws?!”

The shipgirls jolted in shock.

As expected—

The Zero-Homers had mastered the strongest weapon in the Trisolaran universe, said to be wielded only by gods—

—”Mathematical Laws.”

—

—

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