Crossover Shipgirls: Building a Dimensional Empire from Scratch

Setsuna gazed at the row of species entries before him, lost in thought.

He had just found the direction for the Empire’s next expansion goal.

”Flügel, Ex-Machina, Elves...”

The Flügel were a race of god-slaying weapons created by divine hands—possessing near-immortal lifespans and tremendous magical adaptability. They were even stronger than the mass-produced Angeloids.

The Ex-Machina were a gestalt mechanical species, capable of merging multiple individual units into a single collective entity.

Of course, Setsuna knew exactly where these species came from.

[No Game No Life]

Though this world had yet to be located, the fact that its species appeared in the encyclopedia meant it must exist somewhere.

Even if it was far away, he would find it eventually.

And beyond those fascinating species, there were a few things in that world that also interested him—

For example, the Suniaster that symbolized absolute dominion.

”Interesting...”

He was browsing through the remaining entries when—

Beep—

A sudden system prompt echoed in his ears.

[Host Civilization’s Species Encyclopedia has reached the required number of entries. Civilization level confirmed: Space Age. Encyclopedia reward unlocked.]

”???”

Setsuna was stunned.

The last time he received an ”Encyclopedia Reward” was... when?

It had been ages ago—back when he first brought back the Spirits from Date A Live. After gathering five species, the system rewarded him with a magic tome: Presence Concealment.

Its effect completely masked information and allowed perfect assimilation with the world.

He had used it often when his adventuring squad explored the Goblin Slayer world, preventing the local gods from interfering.

It might come in handy again if he ever had to deal with a higher divine world.

”So why didn’t I get any more rewards after bringing back so many new species?”

He voiced his existential frustration.

The time gap just felt... far too long.

[You had not accessed the Encyclopedia interface previously; therefore, rewards were withheld. Additionally, certain rewards require civilization advancement to unlock.]

The emotionless system voice answered mechanically.

”So you couldn’t just send the rewards straight to my inbox? I have to log in every time to claim them, huh...”

”...”

After a moment of silence—

[Verification complete. Host civilization status: Space Age (FTL).]

[Productivity: Satisfactory.]

[Technological Capability: Satisfactory.]

[Total Resources: Satisfactory.]

...

Following what felt like a full-blown qualification audit—

[Host civilization meets requirements. Issuing corresponding reward.]

[Please continue guiding your civilization to higher levels.]

Vmmm—

A holographic interface appeared before him.

Massive streams of data flooded into the Eternal Snowfall’s database—so much that even the Juggernaut’s onboard AI briefly crashed.

[Ascension Technology Unlocked: Galactic Wonder]

[Ascension Path Options Available: Galactic Nemesis / Cosmogenesis]

He opened part of the documentation casually.

[Galactic Wonder]

Unlocking the Galactic Wonder allows construction of various Megastructure Projects—massive engineering wonders that serve as symbols of an empire’s power on a cosmic scale. Each miracle provides unique, powerful effects.

Such colossal feats of engineering could only be achieved by spacefaring civilizations with extraordinarily advanced technology and productivity.

A true wonder of the Age of the Stars.

Setsuna understood immediately.

He had built a ”Wonder” before—the Array of Sundial.

Once activated, its ”Ceasefire Field” provided near-absolute defense.

Unfortunately, with no real enemies in this universe—and during interdimensional wars, no foe strong enough to reach the capital—it had little opportunity to shine.

He remembered that back in the early technological era, the Array of Sundial had taken ages to construct.

Now, with civilization and productivity both vastly improved, it finally made sense that the system had unlocked higher-tier wonders.

”Honestly, I’m pretty sure the engineering division’s research lolis and Grey could’ve discovered this tech themselves...”

Setsuna muttered to himself with a smirk.

Thinking it over, though—having it sent directly to him was definitely more convenient.

After selecting the Galactic Wonder project, a list of numerous sub-projects unfolded before Setsuna’s eyes.

[Galactic Wonder: Sentry Array]

Prerequisite Technologies: Megastructure Engineering Theory, Tachyon Sensor Systems, Sentient Artificial Intelligence.

A massive structure to be constructed on a non-stellar celestial body. Once completed, it grants ultra-cluster-level galactic vision—allowing real-time monitoring of all star systems, fleets, and biological movements across the Milky Way and surrounding clusters.

By building additional nodes and upgrading its power network, the monitoring range can be expanded even further.

Simply put, the Sentry Array functioned like an interstellar map reveal—real-time surveillance of the entire galaxy. Combined with the Sophons, there would be nothing that could escape his sight.

Moreover, its operational range wasn’t limited to a single galaxy anymore.

The sheer amount of documentation for the Galactic Wonder was overwhelming, containing countless prerequisite theories and technologies.

Setsuna skimmed through a few pages—he couldn’t make sense of the physics, but he could tell from the data that it followed the same logic as building a Gundam: one step at a time.

Turning another page, he found a list of various other wonders:

[Ring World]

A massive megastructure encircling a star, composed of multiple planet-sized segments.

Climate, gravity, and temperature can all be freely controlled, offering the highest possible habitability for all races.

Constructing a Ring World requires an enormous amount of material—typically by dismantling entire celestial bodies within a star system.

[Matter Decompressor]

A megastructure built in orbit around a black hole.

By twisting gravity deep into the singularity and using automated decompressors, processors, and forges, it can extract virtually limitless minerals from the black hole itself.

[Gateway]

A galactic network enabling instant travel between systems.

Once a ship passes through a Gateway, it can immediately arrive at any other connected gate—distance rendered meaningless.

...

In addition, there were projects such as the Quantum Catapult, Strategic Coordination Center, Dyson Swarm, and Dyson Sphere, among many other extraordinary constructions.

Most of them originated from the Stellaris universe, though many designs had been further enhanced in function.

The power of the Galactic Wonder was beyond question—especially when combined with the technologies he had gathered from other worlds, producing effects greater than the sum of their parts.

The Sentry Array, paired with the Sophons, could form a surveillance network spanning the entire cosmos.

The Gateways, combined with Transwarp Anchors, would allow instant travel across all vassal worlds and subordinate universes within the Empire.

And the Matter Decompressor—extracting resources directly from a black hole—was simply insane.

”...”

Setsuna reviewed the Galactic Wonder in its entirety, his heart racing.

How could a reborn civilization lack wonders?

Without the Galactic Wonder, could the Starsea Empire truly call itself the Starsea Empire?!

Classical wonders like Petra or the Hanging Gardens belonged to the past—now was the age of the stars, and the Empire must claim its own cosmic monument.

Then, his gaze fell upon an intriguing new option.

[Available Ascension Paths: Galactic Nemesis / Cosmogenesis]

”Hmm...”

Either path would grant the construction of a monumental megastructure—the pinnacle of wonders in its own right.

He pondered briefly.

Shuaa—

Opening a holographic channel, Setsuna connected to the Starbase communications network and called up a familiar contact—the Bulin forewoman often responsible for refitting his ships.

”Bulin Engineering Division, assemble! Bring the Manjuu and Angeloid teams to report immediately!”

”Also, summon Kayo Senju, Daedalus, Grey, Observer, Compiler... everyone, gather up!”

”The Empire needs you—time to build a miracle!!!”

...

Inside the administrative center—

Most of the Starsea Empire’s research and engineering departments had been summoned, and even a portion of the colored Bulins were gathered before Setsuna.

”Ahem. To put it simply—we’re going to build a wonder.”

He uploaded all the data on the Galactic Wonder into the Imperial database.

”Eh?”

Kayo Senju, Daedalus, Grey, and the Siren girls all leaned forward curiously, studying the holographic interface with intense focus.

”Oh, I know this thing.”

The nanobot lifeform glanced at the data, immediately understanding what it was.

”About sixty million cycles—no, one hundred and twenty million cycles ago—I saw a Creator build something like this in the L-cluster.”

”A Dyson Sphere, huh? Encasing a star to harvest its energy... personally, I think it’s more of a vanity project.”

”I’ve also seen things similar to the Strategic Command Center and Sentry Array. They spent tons of time and resources building them—but I broke them afterward.”

”Didn’t leave much of the tech behind, though...”

She recalled her feats as if it were the most natural thing in the world.

”...”

The other researchers looked at her like they were staring at a ghost.

”Mining from a black hole?! What the hell, Commander, are you telling us fairy tales?!”

”Real-time surveillance over an entire supercluster?! What kind of hyper-advanced sensor technology could even make that possible?!”

”No, wait—to process that much data, we’d need a supercomputer trillions of times more powerful than what we have now...”

The research lolis, Siren scientists, and Daedalus exchanged bewildered glances.

Just a few years ago, many of them couldn’t even read—scavenging scraps from underworld slums. And now? They were helping the Commander design cosmic-scale megastructures.

Standing at the frontier of astrophysics and cosmic engineering.

It was insane. The universe truly worked in mysterious ways.

They studied the files Setsuna had brought, their eyes filled with awe.

The sheer scope of the schematics alone conveyed the overwhelming grandeur of the Galactic Wonder.

Planetary- and stellar-scale structures—so massive they would be visible to the naked eye across astronomical distances.

True monuments of an interstellar empire’s strength and pride.

”If we could someday build a Strategic Command Center, a Sentry Array, and a Megashipyard within the Solar System... this place would become the true capital of the Empire,” Kayo Senju murmured, scratching her head as a grand vision took shape in her mind.

In her imagination, the Imperial Capital system was filled with these colossal structures—each one a wonder of the stars. From here, they could oversee all movements within the supercluster.

Using Transwarp Anchors and Gateways, they could instantly mobilize forces to every vassal world and every corner of every subordinate universe.

Matter Decompressors would continuously draw infinite resources from nearby black holes, enabling the Megashipyards to assemble vast imperial fleets in record time.

If they wished, they could even construct a Ring World within the Solar System.

The Starsea Empire had such abundant resources that it wouldn’t even need to dismantle entire star systems. Natural celestial bodies and wonders could coexist—a cosmic combination of nature and miracle.

”...”

Everyone was utterly absorbed by the awe-inspiring designs, losing track of time.

It wasn’t until Richelieu gently spoke up that they realized several hours had already passed.

”Well? What do you think?” Setsuna asked.

”...”

”Uh...”

The research division exchanged uncertain looks until Daedalus finally spoke up thoughtfully:

”The data is detailed. Some of the theories are still too advanced for us, but I believe they’re valid.”

”These wonders are incredibly powerful—but building them would require an unimaginable amount of resources.”

”For an average spacefaring civilization, constructing just one would take years—or even decades—of resource accumulation. To build them all, including the Matter Decompressor, Dyson Swarm, and Ring Worlds, we’d need to construct several at once...”

”The total cost would be astronomical.”

”If it doesn’t bankrupt you, is it even worthy of being called a wonder?”

Setsuna smiled faintly.

He had already mentally prepared himself for this.

High investment, high return—that was the defining trait of the Galactic Wonder.

—Aside from the occasional vanity project.

”Fair point...”

The research leads discussed it for a while longer.

”Commander, from a practical standpoint, I recommend prioritizing the construction of production-type wonders such as the Matter Decompressor, Arc Furnace, and Dyson Swarm first,” Kayo Senju suggested, raising her hand.

”Functional types like the Sentry Array and Gateways can proceed simultaneously. As for the Ring Worlds, Orbital Megabase, and Quantum Catapult—those can wait.”

”Since the Starsea Empire is vast but sparsely populated, everyone could still fit comfortably within the Solar System. The need for habitation structures isn’t urgent.”

”By enhancing our productivity through these wonders first, we can plan the rest afterward.”

”...”

”Agreed.”

After a moment’s thought, Setsuna approved the proposal.

”Distribute the blueprints. Build the wonders within the Solar System if possible; if not, choose other suitable star systems.”

”Understood.”

The departments quickly began mobilizing.

”But what about manpower for constructing these wonders?” Grey asked, raising a valid point.

The Galactic Wonder’s complexity far exceeded that of ordinary structures—even top scientists would need time to study and adapt.

”Do I really need to teach you that?”

Setsuna rubbed the head of a nearby colorful Bulin who had been eavesdropping curiously.

”Can you help me build a wonder?”

”Burin?...”

The colorful Bulin tilted her head, pretending to think for a moment.

”Burin’s been listening the whole time and even reading the files! We’re going to build something big! Burin thinks it’s totally doable! As long as we have enough resources, we can start right away with Super Meow-Meow Unit No. 1 Burin! ”

”Mm! But only I can do it—my two dumb sisters definitely can’t!!!”

”...”

Setsuna spread his hands toward Grey.

”See? Problem solved.”

”...I actually tried to challenge a Bulin’s intellect with science. Truly, I was naive,” the nanobot sighed, admitting defeat.

...

Once the construction assignments for the wonders were arranged, Setsuna turned his attention to another prompt.

[Available Ascension Paths: Galactic Nemesis / Cosmogenesis]

These were the two ”Ascension Perks” routes.

The interface provided detailed descriptions:

[Galactic Nemesis]

Every great creation demands sacrifice. Others may not understand, but they will obey.

Unlocks Star-Eater and Aetherophasic Engine.

[Star-Eater]

Armament of doomsday starships equipped with stellar annihilation cannons capable of destroying suns.

[Aetherophasic Engine]

One of the ultimate wonders of the Ascension Perk. Must be built within a stellar framework.

Once activated, it generates an energy surge powerful enough to tear through both lower and higher-dimensional barriers, merging two universes into one.

When used on another universe, it completely drains all matter and energy from it—harvesting every last resource.

Devastating.

Setsuna remembered the Aetherophasic Engine’s original purpose: to drain the Void Realm and elevate an entire species to a higher-dimensional plane—ascending to godhood.

But this universe lacked any Void Realm—Lukoa and Tohru had already confirmed that.

This version of the Aether Engine, however, adapted perfectly to the multiverse.

—Not only could it drain the Void, it could drain other universes.

Just like a giant cosmic pump, it would suck another universe dry—completely and efficiently.

Activate it during an interdimensional war, unleash the Aether Engine, and erase the enemy along with their universe—while claiming all their resources.

No wonder it was the ultimate wonder in Stellaris, triggering instant victory upon activation.

Then, he turned his gaze to the other path.

[Cosmogenesis]

Time, gravity, and space are the fundamental components of reality. To master them is to command all creation.

Unlocks Rules of Reality technology and Horizon Needle.

[Rules of Reality]

Grants the ability to alter physical laws on a universal scale. Every constant or principle can be rewritten at will.

[Horizon Needle]

A vessel capable of traversing space-time and penetrating black holes to reach alternate planes.

”...”

If Galactic Nemesis annihilated universes through force—then Cosmogenesis reshaped them through intellect.

While the former drained existence dry, the latter rewrote it entirely.

With Rules of Reality, he could freely alter the laws of the cosmos—

Anything from rounding π to changing the speed of light, or shifting the wavelength of visible light itself.

Even more absurd than the ”God-tier Civilizations” of the Three-Body world—and infinitely more fun.

”...Damn.”

Both options were overwhelmingly tempting—the Aether Engine pump was terrifyingly powerful, but rewriting the laws of the universe was just as enticing.

Giving up either felt wrong.

”I’ll take both.”

—

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