Crossover Shipgirls: Building a Dimensional Empire from Scratch

Building a new heaven in another world was a completely novel experience for the Starsea Empire.

The Gods of Fantasy and Reality had once served as the ”administrators” of this realm—able to manipulate human destiny and guide the course of the world itself.

Now that all those gods had been eliminated, the authority to manage this world fell entirely into the hands of the Starsea Empire.

Whoosh—

Eris, El, Regina, and the other goddesses from the KonoSuba passed through the portal, arriving in what had once been the ”Heaven” of the Goblin Slayer world.

It was completely empty—every god devoured cleanly by Nyarlathotep and Shabuko.

”Hm, looks like we’ll have to rebuild everything from scratch.”

The goddesses surveyed their surroundings.

From heaven, they could observe every movement of the world below from a higher-dimensional perspective.

To them, the mortals on the surface appeared like chess pieces upon a board.

”Can we directly control them?”

Regina, Goddess of Puppets and Vengeance, attempted to project her divine power downward.

An adventurer exploring in the wilderness suddenly felt a strange force enter his body—an unfamiliar power, not granted by any of the previous gods. His mind grew clouded, and his will faltered.

The Puppet Goddess could manipulate both body and soul, turning people into literal pawns on her board.

”Stop—that’s not allowed.”

Eris intervened, halting Regina’s reckless experiment.

”Our duty is to help the Commander manage this world properly. If you behave like that, how are you any different from the old gods?”

”Ugh... fine.”

Regina withdrew her power.

Back in their former heaven, Aqua had held seniority among them. But after joining the Starsea Empire, Eris—whose followers were the most numerous and whose power had grown the greatest—became the leader of the goddesses.

”This world once had gods, and the mortals here were deeply devout. We can gather plenty of faith energy here,” Eris said thoughtfully.

”But... I suppose we’ll have to teach them to worship new gods now?”

Eris remembered another rather awkward problem.

The natives of the Goblin Slayer world had worshiped all manner of deities—Supreme Gods, Earth Mothers, and countless others.

Their entire magical system depended on divine blessings—”miracles.”

They prayed to their gods directly, receiving power according to their devotion. Different gods granted different miracles.

But now that those gods were gone... so were their miracles.

Countless clerics found themselves powerless in battle, praying in vain.

The only response they received was:

”We’re sorry, the god you are trying to reach is no longer available. Please check the name and try again.”

A living nightmare.

”That’s simple enough. From now on, the Goblin Slayer world will be a fully managed vassal state of the Starsea Empire. Whatever the natives believe in—it’s our call.”

Hearing Eris’s report, Setsuna waved his hand casually.

Countless Bulins and Angeloids flooded into the Goblin Slayer world, announcing the Empire’s dominion over it.

—Previously, the world had merely been treated as a training ground, not officially conquered.

Now came the real reconstruction. All the old temples and shrines to the dead gods were demolished, replaced by sanctuaries devoted to Eris, El, and Xenalis.

Even the Axis Church wasn’t forgotten. As long as Aqua didn’t cause trouble, Setsuna allowed her to spread her faith freely.

After all, teasing the airheaded goddess was one of life’s little pleasures.

”???”

The natives were utterly stunned.

They could only watch helplessly as the great cathedrals that had stood for centuries were torn down and replaced with the statues and altars of unfamiliar new deities.

The Angeloids proclaimed the arrival of new gods to all.

”This world—including its gods—has been completely conquered by the Starsea Empire.”

”The Gods of Reality and Fantasy, those ancient and corrupt beings, have been destroyed by the Empire.”

”The new gods have assumed control. From now on, offer your prayers to them.”

It was a total overhaul—both of divine and mortal power.

For the inhabitants of this fantasy realm, it was nothing short of world-shattering.

The common folk were terrified enough—but the clergy were devastated, unable to accept the truth. Again and again, they prayed to their former gods.

But no matter how many times they prayed—

There was never any answer.

The Angeloids tirelessly spread the teachings of the new faiths among the people.

”Believe in the Church of Eris, and you’ll be blessed with good fortune—like getting rare loot more often when opening treasure chests.”

”Those who worship Xenalis can learn the Resurrection spell once they reach higher ranks as priests or mages...”

”As for the Axis Church—here’s their doctrine. Basically, Aqua’s followers are all cheerful idiots who live happily and carefree. There’s joy in being blissfully brainless, you know?”

”...”

At first, the people were completely bewildered by these new gods from another world.

No one dared worship unfamiliar deities.

But soon, the clerics realized the grim truth—since their former gods were dead, all their divine powers were gone.

Either they converted... or they became useless.

So, tentatively, they began to pray to the new gods.

And then—

They discovered the Heaven’s Goddesses truly responded with blessings.

The powers differed slightly from those of the old gods, but they were undeniably real.

Word spread like wildfire.

Within two weeks, every cathedral of the Heaven’s Goddesses in the Goblin Slayer world was filled with believers.

Guided by the Angeloids, people prayed devoutly and offered tributes.

In this fantasy realm, faith was far more intense than in technological worlds. Commoners clung to it as spiritual sustenance, adventurers sought blessings before each quest, and the clergy—most of all—devoted their entire hearts.

The resulting faith energy was immense.

”Hm, I feel like I’m constantly getting stronger...”

Inside the grand cathedral at the capital’s church headquarters, Eris could feel a ceaseless flow of faith converging from every vassal world.

Even in her sleep, she could hear the constant messages:

”Faith +1, Faith +1...”

...

”So this means the new gods have fully replaced the ancient gods?”

In the administrative center, Setsuna chuckled as he read the latest reports.

It wasn’t just the Goblin Slayer world natives affected—even some who had joined the Empire from there were feeling the change.

For instance, the Sword Maiden, the Priestess, the Hero Girl, and the Elf Archer—all girls who’d once been brought back from that world.

Their signature abilities—Sword Maiden’s Holy Strike, the Priestess’s Heal and Holy Light—were all derived from local divine systems.

Now, they no longer worked.

”It’s fine, Commander. I’ve already learned plenty of new techniques here. Even without those miracles, I’m stronger than ever,” the Sword Maiden said respectfully.

After genetic ascension and super-evolution surgery, even an ordinary person who learned a few moves from the Taixuan Eminence could dominate most mid- and lower-tier worlds.

”Me too, me too! The healing spells they teach at the Magic Academy are even more convenient than miracles...”

The Priestess replied timidly.

She still wore her familiar blue-and-white cleric robes, though she had grown a bit since her arrival. Her small, earnest figure remained adorably pure.

”I heard Nyarlathotep and Shabuko are gods too—and really powerful ones. Can I ask them for a miracle?” she asked curiously after a moment’s thought.

”Don’t.”

Setsuna’s expression darkened immediately.

”Their moral standards are high enough—they wouldn’t curse a devotee like those deranged evil gods—but... are you sure you could endure an Outer God’s blessing?”

”Eep—!”

The Priestess shivered, recalling the indescribable horrors of the Cthulhu gods, and quickly shook her head.

”Hm...”

”Well, still, it’s kind of a shame that some miracles are gone for good...”

Gudako rested her chin in her hand, thinking aloud.

”Oh, I remember one that was super useful—it was called Resurrection, right? The one that could completely restore someone... but had some weird condition for use?”

”You mean the one that only works on virgins?”

Setsuna raised an eyebrow.

”Yeah, that useless miracle was doomed from the start. Why would anyone keep a skill like that around?!”

...

Time flew by.

Under the efforts of the goddesses, the new heaven of the Goblin Slayer world gradually stabilized.

By utilizing the divine authorities left behind by the former gods, they could still create dungeons and labyrinths within the world for adventurers to explore.

Members of the Demon Slayer Corps, Night Raid, and Konosuba squads often traveled between worlds to hone their combat skills.

With the Heaven’s Goddesses personally overseeing operations, there was no longer any need for shipgirls or other high-level entities to act as safety nets. Even if something went wrong, the goddesses could instantly intervene to rescue anyone in danger.

”Eris-nee! Eris-nee! Can you make another dungeon for us? I wanna test my newly upgraded Explosion Magic!”

Megumin, Yunyun, and the other Crimson Demon lolis surrounded Eris, tugging at her sleeves and pleading adorably.

”...Each of you can only run one dungeon per week, okay? Others still need their turns too.”

Eris smiled, patting their heads.

With a gesture, she summoned a floating holographic interface before her.

”Let’s see... judging by your power level, you should be fine with a Demon God-tier dungeon. Want something easy or challenging?”

”Hard mode! We want to train through combat!” Yunyun said immediately.

”Alright then.”

Whoosh—

Divine energy surged.

In a remote corner of the world, a ruined Demon King’s castle was instantly restored to its full glory.

An ancient Demon God awakened beneath the earth, slowly rising to take his seat upon the throne. Mechanisms across the dungeon clicked into place as guardians were deployed one after another.

In moments, an enormous Demon Lord–class dungeon—on par with the ones from the Konosuba world—had been constructed.

”All done. Go on, and be careful.”

Eris patted Megumin’s head.

”Thank you, Goddess-sama!!!”

The Crimson Demon lolis cheered, rushing off noisily toward the dungeon.

”Um, we’d like to train our swordsmanship too... would you have time to oversee us?”

Not long after, Shinobu Kocho, Akame, and several others approached, raising their hands timidly.

Similar scenes unfolded across the realm—each goddess managed a different region, maintaining the dungeons there, granting blessings, and safeguarding adventuring parties.

With goblins and other abominable creatures completely exterminated, the surrounding cities and villages enjoyed newfound peace.

For the Starsea Empire, the Goblin Slayer world had now become a grand amusement park.

Whether one wanted to challenge dungeons for fun or to train seriously, all they had to do was buy a ticket from the goddesses.

Thanks to the world’s unique nature, adventurers could even harvest materials and equipment from slain monsters—an all-around win.

...

Elsewhere—

Clack—

While waiting for his world-hopping cooldown to reset, Setsuna spent his days in the capital, training to increase his synchronization rate with Unit-01.

He sparred with the other Outer God girls using the EVA, or meditated to deepen his understanding of the chaotic energy within it.

Each incremental increase in synchronization gave him a firmer grasp of Outer God power.

Bang—Clash—

Inside the training arena, he and Kuuko traded blows for several rounds.

Eventually, both sat down, panting and exhausted.

Operating the Outer God–type EVA drained far more energy than piloting Strelizia or even the Eternal Snowfall—and it also consumed his mental stamina.

”Up by 20%, huh...”

He glanced at the synchronization display—nearly 130%. Still far from 400%, but considering how little time had passed since obtaining the EVA, his progress was extraordinary.

Using the Eternal Snowfall’s time-warp field, he could accelerate training even further.

Whoosh—

With a thought, he extended his hand and condensed a mass of black energy.

”Oh? Commander, you’ve really synced well with Nyarlathotep’s avatar, huh? You can use her energy even without piloting?”

Shabuko and Kuuko exchanged amazed looks from the sidelines.

”This means your body’s starting to adapt to its presence,” Kuuko noted.

Being able to manifest Outer God energy barehanded meant the fusion between them was steadily progressing.

”Mhm.”

Setsuna still wasn’t entirely sure what this new power could do—but he could feel subtle changes occurring within his body.

”Commander’s not gonna turn into a tentacle monster, right?!” Origami Tobiichi asked with genuine concern.

”Ah... but if Commander did turn into one, I wouldn’t mind. That way, he could use more... techniques... with me—”

”Stop right there!”

Nyarlathotep quickly interrupted Origami’s R18G-level fantasy.

”Cthulhu gods aren’t just all tentacles, limbs, and eyeballs, okay?! I have several perfectly normal avatars—and there are elemental Outer Gods too!”

”If Commander ever fully masters this power and becomes an Outer God himself, he’ll definitely be able to control his appearance.”

”Huh?” Jeanne Alter blinked. ”Then why do your true forms all look so... sanity-breaking?”

”...We were young and stupid back then. Made them like that just to scare people.”

”...”

Setsuna couldn’t deny that explanation fit perfectly with Nyarlathotep’s particular brand of cosmic absurdity.

”Oh right, Commander.”

”Why don’t we, uh... have another deep synchronization session tonight? Maybe it’ll boost your sync rate again?” Nyarlathotep whispered, leaning close as she massaged his shoulders.

”If there’s anything you don’t understand, I can teach you personally...”

”Damn it.”

If it were Chen Hai, Yat Sen, Kurumi, or anyone else asking that, Setsuna would’ve raised no objection—he’d have gladly spent the night showing them who was boss.

But when it came to this energy-draining demoness of an outer goddess, he knew better.

”I’m spending tonight with Scáthach and Nero.”

”Then I’ll join too.”

”...Scáthach still has psychological trauma from the last time you were around. Isn’t that... problematic?”

”Guh...”

Nyarlathotep pouted, lightly pounding his back with her fists.

”Then tomorrow! I can use time-distortion magic too—let’s spend a month together! Ehehehehe...”

”...Fine.”

Setsuna sighed, feeling a phantom ache in his waist.

With his body’s endurance, he could easily handle shipgirls, Spirits, and even Heroic Spirits—heck, even Observer could be reduced to a lovestruck mess, making peace signs and walking bow-legged.

But these Outer Gods... were another story entirely.

The Three Pillars truly were terrifying.

He’d better keep up his physical training.

...

After the session, Setsuna performed his usual patrol around the capital.

He was just about to be dragged off to the dorms by a group of bickering shipgirls when suddenly—

Beep—

A holographic alert flashed before him—an incoming message from the Starbase.

Observer’s delighted face appeared on the screen.

”Commander, we’ve accomplished something great!”

”The Eternal Snowfall’s refit is complete—or rather, we’ve successfully installed a Transdimensional Engine onto your ship’s frame... and elevated it to six-dimensional status!”

...

...

Whoosh—

Half an hour later, Setsuna and several shipgirls arrived at the Starbase docking area.

”Hi hi hii~ Commander! You left us baking in the sun doing all the work while you were partying back at the capital, huh~?”

Observer leapt into his arms, her mechanical tentacles flailing playfully.

”I invited you to plenty of parties too. Don’t start.”

Bonk—

He flicked her forehead lightly, glancing toward the other Siren girls nearby who looked on in envy.

”So? The transdimensional ship refit’s complete?”

Since returning from the Three-Body world, the Sirens had been researching advanced dimensional technology—trying to turn the Dual-Vector Foil into a controllable, instantaneous, high-efficiency weapon of dimensional reduction.

But during their research, an idea struck them: if they could decrease the enemy’s dimensional level... why not try increasing their own?

Using one of the Eternal Snowfall’s smaller escort ships as a testbed, they performed endless experiments and radical modifications—hoping to make it ascend dimensions.

”Yes!”

Purifier’s face beamed with pride.

”We’ve completed full-spectrum transdimensional adaptation and installed an experimental Transdimensional Engine—upgrading the vessel by three full dimensions!”

”It includes one macroscopic dimension and two temporal dimensions.”

Following the Siren girl’s gesture, a silver-white starship came into view, docked at the far end of the shipyard.

At first glance, it still retained the sturdy, angular design of a warship—visually similar to the smaller vessels of the Eternal Snowfall fleet.

But the group quickly noticed something... strange.

Its hull was completely sealed. Every segment seemed to fold seamlessly into the next, as if the entire vessel were a Klein bottle or a Möbius strip.

No scanning devices could penetrate its structure—its interior layout was utterly indecipherable.

And yet, when viewed from space, the ship produced massive visual distortions. Its apparent size defied logic.

Nearby, an identical-class battleship that was theoretically the same size looked as tiny as an ant beside it.

”Is it really that big?! It looks almost as large as the Eternal Snowfall herself!” Formidable gasped.

”That’s its three-dimensional projection. The visual distortion is normal,” explained Compiler calmly.

”This vessel exists fundamentally in six dimensions. Unless we ascend to the sixth dimension ourselves, we can never see its full form.”

Setsuna and the shipgirls paused for a moment before realization dawned on them.

It was like imagining a two-dimensional world—a painted sheet inhabited by flat people. No matter how rich or colorful that painting might be, those 2D beings could only perceive the sides of the world around them. Everything they saw appeared as lines of varying lengths.

Only if one of those flat beings somehow drifted out of the painting—into the three-dimensional world—could they turn back and finally see the artwork’s complete picture.

Right now, what everyone was seeing was merely a fragment—the ship’s projection in three-dimensional space.

”Whoa...”

Setsuna was in awe at the transdimensional vessel’s impossible design.

In starship engineering, size alone no longer defined power. Beyond the Juggernaut-class level, the only further steps were planetary- or stellar-scale warships.

A dimensional upgrade, however, represented a completely new frontier.

”You said this ship includes two time dimensions, right?”

”Yes.”

Compiler and Observer both nodded.

”With two temporal dimensions, it no longer moves linearly through time.”

”It can travel both into the past... and the future.”

—

—

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