Crossover Shipgirls: Building a Dimensional Empire from Scratch

After leaving the solar system, the starry sky no longer held the concept of day and night; the cycle of light was regulated by the holographic dome.

At the top of the Eternal Snowfall’s bridge, inside the master bedroom—

As the dome emitted a warm and gentle glow, Cecilia slowly opened her eyes and glanced around.

It felt as if she were floating in an endless sea of stars.

Outside the vast floor-to-ceiling window and overhead alike stretched a magnificent expanse of glittering constellations.

Not far away, faint and sparse nebulae could be seen, painting an ethereal vision in the dark expanse of space.

”Where... am I...?”

She yawned. Having stayed up far too late last night, she hadn’t slept enough and was still groggy.

”We’re currently near the Kepler-11b system, about two thousand light-years from Earth,” Setsuna said, leaning against the bedframe while bringing up a holographic display.

”Oh, and if you used an ultra-precise astronomical telescope to look toward the solar system right now, you’d see Augustus ascending the throne.”

”Astronomy and cosmology are pretty fascinating, aren’t they?”

”???”

Cecilia blinked in confusion for a while before processing what he said.

”Wait—seriously?”

”In theory, yes. The distance is just right for that light travel time. But the Eternal Snowfall uses tachyon sensors, so our data is instant.”

”Of course, if you really want to watch Augustus’s coronation live, I could figure something out.”

Setsuna said casually, reaching over to ruffle her hair.

”Ah?...”

Cecilia stayed dazed for a few seconds, then shook her head.

”No, no, never mind Augustus for now.”

”You actually dared to... last night—”

She pouted and gave Setsuna’s arm a playful pinch.

”You didn’t exactly refuse either.”

Setsuna pulled her into his arms.

”That’s... that’s...”

Cecilia puffed up her cheeks.

She wanted to say she never stood a chance against him.

A pure-hearted maiden was helpless before an experienced veteran—completely at his mercy.

Just a few sweet words and she had lost all sense of direction. Only after waking up this morning did she realize what had happened last night.

”You have to take responsibility! You have to marry me!”

She clung to Setsuna’s arm, tilting her head up with an indignant pout.

”Sure.”

Setsuna agreed without hesitation, feeling the soft, delicate warmth of her touch. The two of them were, after all, entirely bare before each other.

”Guh...”

Cecilia blinked and then asked, ”What’s your relationship with the girls on this ship? Tohru, Formidable, and that one with the really long ahoge...?”

”They’re all my wives.”

Setsuna said truthfully.

”Ah—Ahhhh?!—”

The innocent maiden took another emotional hit and pounded on his chest twice.

”Playboy! Playboy!”

”I thought you and the others like Tohru and the rest were just colleagues—you all act so proper!”

Pfft—

Setsuna almost burst out laughing.

He wrapped his arms around her and lightly tapped her forehead.

”I’ve been in the dockyard for so many years, and you think I’m just colleagues with the shipgirls? You don’t suspect I might have... issues?”

”...”

Cecilia pouted and thought about it.

It did make sense.

But after last night, she had no more doubts—her waist still ached.

”Fine, but you can’t ignore me after this! If you do, I’ll tell little Kiana and Sirin that their father is a shameless womanizer.”

She pinched his cheek teasingly.

”Only you could come up with that.”

Setsuna flicked her lightly.

”Don’t worry. We can all spend time together aboard the Eternal Snowfall and deepen our bond.”

”You think of Hua as your senior, right? You can come along with her next time.”

”Eh?...”

...

Hum—

After cruising through outer space for a while, the Eternal Snowfall finally returned to the space station.

It wasn’t until Setsuna demonstrated his ability to freely retract and project the starship’s hull before her eyes that Cecilia finally understood—the Commander wasn’t just the ”brains” she had imagined, responsible only for issuing orders.

In a certain sense, he was among the most formidable beings in the entire Starsea Empire.

The two of them spent several days exploring outside. When they returned, the space station remained largely unchanged.

Seeing Cecilia clinging to Setsuna’s arm with affection and a hint of shyness, most people immediately understood what had happened.

”Yo?—”

”Looks like you two have been enjoying yourselves. Don’t tell me you’re planning on having a third child?”

Grey greeted them casually.

”Eh?... What are you talking about...”

Cecilia’s face turned as red as a ripe persimmon.

”...Schicksal is going to be furious.”

Cheng Lixue sighed.

If an alliance through marriage could be formed with the ruler of the Starsea Empire, the three great families would probably be willing to send all their subordinates over. The potential benefits were beyond measure.

Unfortunately, Cecilia had given herself away for free—and aside from her surname, she no longer felt any real connection to the Schariac family.

”I actually like her quite a bit,” said Formidable, twirling her hair as she observed Cecilia from a distance.

”Gentle, sensible, loves children... she’s the perfect model of a virtuous wife and loving mother.”

”...Why do you sound like you’re picking concubines for an emperor...”

Gudako couldn’t help but complain.

”Ahem—”

”Commander, you’ve lured a pure-hearted maiden onto the ship and spent days of shameless indulgence. Fine, we’ll overlook that for now—but can we get back to business?”

Grey cleared her throat.

”Next time, take me along... oh, wait—let’s first find a way to deal with the Honkai, shall we?”

...

Two hours later.

Inside the space station, the members of the Research Division—including Tesla, Einstein, and others—had all gathered.

”Hmm...”

”Now that Kiana has been born in this post-Honkai era, most of the key people here are already assembled.”

”Conquering this world was merely a side task. Our main goal now is figuring out how to eliminate the Honkai threat.”

On the holographic display appeared a detailed roster.

In the Honkai world, the youngest ones were the trio of founding families. Due to timeline shifts, they had appeared a few years earlier, and their lives had taken subtly different paths.

For example, Anti-Entropy had never been established, Cocolia had been rescued early, and the plotline where Raiden Ryoma was framed and imprisoned no longer existed.

Raiden Mei remained the heiress of ME Corp.

If all went well, she was unlikely to suffer mental corruption from Honkai energy and become the Herrscher of Thunder.

Bronya was already training under Himeko and Theresa at St. Freya Academy.

”What about the kids at the academy?” asked Kallen curiously.

”No need to worry,” replied Grey, waving her hand. ”They’ll come to us in due time. Everything is under control.”

”Now, let’s focus on figuring out how to eliminate the Honkai threat.”

Swish—

She gestured for the Angeloids to distribute the documents to everyone.

”To permanently eradicate the Honkai, the simplest and most direct method is to deal with the Cocoon of Finality.”

”That thing destroyed multiple civilizations across the solar system before, didn’t it? Guess it’s Earth’s turn now.”

From the data compiled aboard Griseo’s Ark, it was clear that during the Previous Era, Mei had already recognized the existence of the so-called ’Finality.’

The Cocoon of Finality was an artifact created by an alien civilization, possessing the power to manipulate destiny itself. Its purpose was to cycle planetary civilizations so that its creators might replicate their kind.

The Cocoon of Finality, embedded at the edge of the Imaginary domain, controlled everything related to Honkai. It was the sole Imaginary singularity, the only Herrscher core.

Its projections across different dimensions led to the sequential emergence of various Herrscher authorities in reality.

The Herrscher of Finality that destroyed the Previous Era had been born from the Cocoon itself—its authority was to reset planets, erase civilizations, and return everything to the beginning.

As long as humanity remained unable to coexist fully with the Honkai, Imaginary energy would continue to flow into the Cocoon, nurturing the birth of a new Herrscher of Finality.

”Uh... Cocoon?”

Several of the newly recruited Honkai scientists looked bewildered.

Although they were native to this world, the Starsea Empire’s Research Division was far beyond them in understanding the nature of Honkai energy.

”Yes, the Cocoon of Finality is the source of all Honkai energy and every Herrscher.”

”Take care of the Cocoon, and peace will follow.”

Grey spread her hands, summarizing in simple terms.

”If we get the chance, we might even visit the other planets of the solar system—there should still be ruins left behind by civilizations destroyed by the Cocoon.”

”Hiss...”

Everyone stared at the data for quite a while.

The concept of the Cocoon of Finality was completely new to Kallen, Cheng Lixue, and Cecilia. Fu Hua had heard of something similar back in the Previous Era, but she didn’t fully understand it.

Setsuna, however, wasn’t surprised. In the Honkai world, facing the Cocoon of Finality was inevitable sooner or later.

”So, what do we need to do?”

Tesla raised her hand, feeling as if she were taking part in something monumental, hoping she could somehow contribute.

”Well... the first question is—how do we even see the Cocoon of Finality?”

Grey explained.

”According to the usual rules of this world, you must first integrate the powers of other Herrschers, gain the Power of Finality, and then you can face the Cocoon.”

”However... that’s a bit troublesome for us.”

Everyone did a quick calculation. Originally, Kiana had to integrate more than ten Herrscher powers—Reason, Void, Thunder, Wind, and others—before she could surpass the Finality.

At present, the Starsea Empire had collected four: Setsuna possessed the cores of the Herrscher of Reason and the Herrscher of Corruption, while the Herrscher of the Void’s core was within Kiana, and another belonged to Senti.

”Uh, didn’t you guys do artificial Honkai experiments before? Maybe we can use that method here—create Herrschers within the station and collect their power afterward?”

Planck suggested.

”That’s one way to do it...” Grey replied.

”It’s just a bit clumsy. Once or twice might be fine, but repeating it too many times would get cumbersome.”

”Back during the Saga of the Shattered Swords era in Shenzhou, we conducted lunar expeditions and discovered remnants of ancient power left by the Previous Era.”

”If we can harness that power, it would save us a lot of effort.”

”Hm... ah?”

Setsuna rubbed his temples as if trying to recall something from long ago.

Before leaving the Honkai world, the research team had visited the ruins on the Moon.

That was where Dr. Mei had sealed the so-called ’God’ in the Previous Era. In the original timeline, Sirin was guided by a mysterious voice and acquired four Herrscher cores there.

The Research Division had practically stripped the entire site bare, including all the ancient relics left behind by the previous era—leaving almost nothing behind.

As a result, centuries later, when Schicksal’s lunar probe landed, they found absolutely nothing.

Even if Sirin had turned into the Herrscher of the Void, there wouldn’t have been anything left for her to do there besides kick moon dust.

”The Commander couldn’t obtain those four cores before, so we plan to forcibly extract them this time,” Grey said matter-of-factly.

Setsuna had tried once already, but the ’God’ hadn’t been willing to share its power. So he’d decided to flip the table and take it by force.

”Is that even possible??!”

Einstein and Tesla were dumbfounded, as if listening to a myth.

The Starsea Empire’s research on Honkai energy was always so advanced it bordered on incomprehensible.

”Of course it’s possible. We’ve been conducting related experiments aboard the Honkai Space Station. It’ll just take a little time to reduce energy loss.”

The lolis of the Research Division were full of confidence.

”If we can extract part of the Herrscher of Finality’s power from the lunar relics, then merge it with the Commander’s own Herrscher authority and the others’ powers, achieving the so-called Finality shouldn’t be difficult.”

”And if we still come up short, we’ll just go with Plan B—trigger artificial Honkai Eruptions, summon a few Herrschers, beat them up, and take their cores.”

Grey stated as if it were the most natural thing in the world.

”...”

For a moment, Fu Hua actually felt a bit sorry for the Herrschers of this era.

In the Previous Era, every Honkai eruption had been a disaster, every Herrscher’s appearance a bloody storm that took countless struggles to resolve.

Now?

In the eyes of the Starsea Empire’s scientists, Herrschers had become nothing more than: ”Hey, fellow traveler, mind lending me your head—oh, I mean, your core—for a bit?”

Lacking a Herrscher core? No problem—just manufacture a Honkai event, summon one, beat her up, and take it.

Like farming monsters in a game.

If the Cocoon of Finality knew Herrschers had fallen this low, would it shed imaginary tears?...

”...Fine.”

”Let’s go with your plan first.”

Setsuna thought for a moment before decisively making the call.

There was no need for him to hunt down every single Herrscher. If they could handle the lunar relics and combine that with his own power, sheer force would be enough to make miracles happen—close enough to perfection.

”I suppose the next question is how to deal with the Cocoon of Finality?” Tesla asked, flipping through the data.

”In the Previous Era, there was the Moonlight Throne—a device that could convert Honkai energy into normal energy. If we could modify it, maybe...”

”Or perhaps we need to gain the Cocoon’s approval? Wait, the Commander is from another world—would the Cocoon even recognize him?”

”And aren’t Herrschers usually female? I still find it odd that we’re talking about controlling Herrscher authority through Herrscher cores. Would the Cocoon even accept that?...”

Einstein, Edison, and several Honkai scientists furrowed their brows, pondering the problem deeply.

”Uh... no, you need to change your way of thinking,” Grey interrupted awkwardly.

”When the Commander stands before the Cocoon of Finality, whether it acknowledges him or not... won’t really be its choice anymore.”

”Oh, and if there’s a chance, Nyaruko, Mio, and I can come along. I’d like to see that thing with my own eyes.”

”...”

Einstein was speechless. As a straight-laced scientist, she still wasn’t used to the Starsea Empire’s way of doing things.

”What I’m more curious about,” Grey said, tapping the holographic screen, ”is the matter of the Imaginary Tree and the Sea of Quanta.”

”The Starsea Empire’s conquest of the Honkai universe shouldn’t just be limited to this one universe, right?”

”The second Divine Key we acquired—the Cosmic Juggernaut—has the ability to open paths toward the Imaginary Tree, which holds countless worlds upon its branches.”

”After we’re done with the Cocoon of Finality, I think we could... take a little stroll through them, perhaps?”

”Hm...”

”Sure.”

Setsuna nodded slightly. He didn’t mind indulging the Research Division’s boundless curiosity.

...

After several time-jumps, everyone settled back into the space station.

They began analyzing and merging the Finality’s power, preparing for their confrontation with the Cocoon.

Every day, the Research Division could be seen dragging strange devices into the testing chamber for experiments.

Odd noises frequently echoed through the corridors:

”Crank up the output!!! If the power’s strong enough, we can rip open a path to the Cocoon of Finality without even needing its power!”

”I mean, it’s just an alternate dimension hidden within the real plane! It’s not like we can’t traverse parallel universes... zzzrrkk—eiil—bzzzt—”

”Uh, technically yes, but instead of building a massive machine like that, maybe we should just stick with the simpler plan...”

”What??!! Sky People? What the hell is that? Scout star located?! Formidable, Illustrious—come with me, we’re going to smack some aliens.”

”...”

It took Setsuna a moment to recall—back around the millennium, Himeko Murata had once encountered the Sky People and the Shoggoth civilization.

They were an extraterrestrial race that roamed the cosmos, seeking out Honkai-rich lower civilizations to invade and plunder.

Himeko was currently teaching at St. Freya, so the presence of the scout star hadn’t yet caused any trouble.

The Sky People sent probes to observe planetary systems along their route, evaluating any possible civilizations. Depending on their level of development, the scouts would transmit coordinates back to their main base.

For less advanced worlds, their fleets would wait until Honkai energy matured and then harvest them.

If they found planets rich in Honkai energy but with weak civilizations, they would strike swiftly—sending forces to conquer and collect the energy.

Setsuna had initially planned to deploy the Eternal Snowfall to intercept them but thought better of it. This was the kind of small matter the shipgirls could handle.

He looked up.

Whoosh—

Led by the gray nanobot warship, several starships launched from the space station.

Zzz—BOOM!!!

Blinding lances of light tore through the cosmos, shattering an asteroid into fragments.

Moments later, countless carrier-based aircraft and Angeloids descended upon the wreckage, scavenging whatever remained.

In less than half a day, they returned victorious with a haul of spoils.

The nanobot commander inspected the recovered material, muttering curses under her breath.

”Harvest Honkai energy? Tch. Do they even know whose turf this is? We’re the ones who do the beating around here—how dare they come here to steal?!”

”Self-destruct? Don’t they know about the Great Principle of Reversible Detection? Trace their origin coordinates!!”

”Once we’re done with the main mission, we’re coming for you... heh, you’re already marked in the Synaptic Lathe!”

”...”

Considering everyone’s strange fondness for beating up aliens—which doubled as both exercise and a convenient way to stockpile fuel for the Synaptic Lathe—Setsuna decided to just let them have their fun.

”Hm...”

Nyaruko crouched among the wreckage they’d brought back, occasionally picking up and sniffing random components.

”They’re not even that strong. They go around the universe stealing Honkai energy—just like pirates.”

”If we hadn’t come, though, this would’ve been way out of Earth’s league, right?”

Setsuna recalled for a moment.

Before the birth of Kiana the Great Sage, humanity probably couldn’t have dealt with the Sky People at all.

”Bad guys. In our world, they’d be punished by Azathoth.”

The Cthulhu goddess expressed moral outrage at such cosmic piracy.

Clack—

She pulled a crowbar out from beneath her skirt and slung it over her shoulder.

”Don’t worry. If they come again, I’ll deal with them myself!”

”...”

Setsuna was silent for a moment, then patted Nyaruko’s head and her ahoge.

”As long as you’re happy.”

—

—

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