Crossover Shipgirls: Building a Dimensional Empire from Scratch

After the Eternal Snowfall activated the time distortion mode…

The companions onboard had various reactions.

Setsuna had only used this ability on a small scale within his harem group before—most people didn’t even know their Commander had such a skill.

Now that the Juggernaut’s interior space had increased a thousandfold, the natural course was to go bigger.

The little lolis all pulled out their homework.

”Onii-chan, can we do our homework here from now on? Hai Tien and Chen Hai gave us way too much holiday homework...”

”If we finish our homework here, we can play more and even catch up on our studies…”

Their thoughts were simple.

Here, 5 days equaled just 1 hour outside. So if they finished their holiday homework aboard the Eternal Snowfall, they could play for many days!

And when they returned to school, only a single night would have passed—they could continue enjoying the vacation!

Many kids hoped to finish their work before the early days of the holiday, and now the Commander’s time distortion skill gave them a dream-come-true opportunity.

”...Aihara Enju, I’m right here.”

Chen Hai folded her arms and smiled as she watched the little lolis.

She wasn’t sure if this counted as cheating, but after a moment’s thought, a plan came to mind:

”Well, since everyone’s already here, why don’t I give you all a supplementary lesson?”

”On the Eternal Snowfall, one semester’s worth of lessons would pass while only a few days go by outside. From now on, let’s use holidays for classes here. Mmm… we can accelerate the teaching pace quite a bit.”

”Commander, how about building a school up here?”

”Waaah!!!”

The little lolis were so scared they practically peed themselves.

They tumbled and scrambled to the hatch, tearfully surrounding a few destroyer shipgirls.

”Can we go back, please? We don’t want to take extra classes up here...”

...

Ordinary people like Akame and Kurome were seriously considering the possibility of training aboard the Eternal Snowfall.

Training here would allow one’s strength to skyrocket.

A month of silent cultivation could match several years in the outside world.

”First, self-time acceleration can’t last that long.”

”Second, I still need to use the Eternal Snowfall for other things, thanks…”

Setsuna cut off Akame’s dream with a deadpan expression.

Among them, the most surprised were the shipgirls who were always close to him, yet hadn’t pierced that final layer of the windowpane.

”Wha—Commander?!”

”So you’ve been doing that on the Eternal Snowfall all along?!”

Formidable elbowed Setsuna hard.

Illustrious and Victorious both blushed and looked down.

As proper Royal ladies, Illustrious-class shipgirls had their elegance, but Formidable had a bit of that fiery noble-lady temper and loved to let loose in front of the Commander.

”Hmm… if you’re not willing, you can leave the ship?”

Setsuna pondered for a moment.

”Go die!!!”

Formidable pounced on him, grabbing his face and twisting it left and right.

Illustrious and Victorious, however, thought for a moment and nodded.

”Um… Illustrious also wants to spend more time with the Commander…”

”If you don’t mind, may we stay by your side…?”

”???”

Formidable suddenly felt like she was about to be left out.

”Wait a minute! Count me in too!!!”

...

The first night after the Eternal Snowfall’s reconstruction, Setsuna spent it with the three Illustrious-class sisters.

The Juggernaut’s bridge and bedrooms were massive—and so were the Illustrious sisters.

In the hundreds-of-square-meters master bedroom on the top floor, Setsuna lay on the bed, gazing up.

Through the holographic dome above, he could see the starry expanse of the universe.

According to shipgirl custom, no one else disturbed him tonight.

Only three generously endowed carrier shipgirls lay around him.

Illustrious and Victorious sandwiched him left and right.

Victorious wore a silky, semi-transparent white gown, accented with gold embroidery—holy and elegant, like a goddess from Greek mythology.

At the same time, the gown was quite revealing. Setsuna suspected that a gentle tug on the golden thread at her chest would unravel the whole thing.

She also had on thigh-high stockings with an open toe and heel design, the fabric looping neatly around a single toe. The bare skin and delicate shape of her feet were clear to see, making them look even more tempting.

Azur Lane shipgirls often pushed their outfits to borderline censorship levels. Only within the port did Setsuna get to enjoy such eye candy.

”Commander, where are you looking? Do you like Victorious that much?”

Seeing Setsuna staring, Victorious leaned in with a smug smile.

”Of course—I like all of you.”

Setsuna had always been honest with his feelings.

In this situation, anyone claiming not to like them was either mentally or physically broken.

”Commander~ Don’t play favorites~”

Illustrious gently took Setsuna’s left hand and placed it on her chest.

”Can you feel Illustrious’ heartbeat?”

”!!!”

Setsuna focused carefully for a moment...

”I can’t feel a thing.”

He couldn’t feel anything!

On a carrier shipgirl, all he could sense was thick armor plating—nothing else.

Maybe Joffre was an exception?...

”You can try feeling it longer… Illustrious’ heart beats faster when she’s near the Commander.”

Illustrious pressed his hand against her with both of hers, eyes filled with tenderness and affection.

”Wife is wife.”

Setsuna was helplessly falling.

Seeing someone else take the lead, Formidable panicked and yanked Setsuna’s other hand.

”Commander, feel my heartbeat too!! I’m not worse than Sister Illustrious!!!”

Still couldn’t feel it.

Absolutely nothing.

But Setsuna just wanted to keep feeling a bit longer—maybe even try another method of sensing.

Victorious quickly picked up on his thoughts.

”Commander, both your hands are taken by Illustrious and Formidable, so… the rest, I’ll take care of it, okay?...”

...

At the Azur Lane port, inside the shipgirls’ dormitory—

A black-haired, green-eyed, short-horned light carrier shipgirl yawned.

She sat up sleepily in bed.

”Illustrious, what time is training today?”

Indomitable knocked on Illustrious’ room door—but no one answered.

Sister ships typically lived together.

She looked around—Formidable and Victorious were missing too.

Knocking door to door, she found most of the dorms empty. Only a few equally homebody shipgirls were still in the port.

”Where did everyone go?”

Indomitable was confused.

Not until she reached the main hall did she spot a carrier shipgirl curled up on the couch playing video games.

”Illustrious, Formidable, and Sister Victorious went to check out the new Eternal Snowfall,” Long Island replied without even lifting her eyes from the screen, a soda and game controller in hand.

”You said you didn’t feel like going, so they didn’t invite you.”

”Eh?”

Indomitable looked up at the night sky, where the faintly glowing Eternal Snowfall sparkled.

”All my sisters are up there?!”

”I… I think I missed something really important?...”

...

Aboard the Eternal Snowfall, time distortion made the days of joy pass in a flash.

Setsuna discovered that ever since gaining the Allspark as a power source and having the ship transformed into a Juggernaut, his strength and physique had skyrocketed several levels.

Shipgirls like Taihou and Richelieu, who used to often request private time alone with the Commander, now eagerly wished for more sisters to help out each time.

With the Allspark included, the Commander had become a tri-core-powered Juggernaut!

It was terrifying.

That morning, while the Illustrious-class sisters were eating breakfast, they couldn’t stop complaining about sore waists and weak legs.

Origami Tobiichi, upon seeing even the mighty carrier onee-sans submit, immediately abandoned her usual proud demeanor and quietly sat to the side, afraid Setsuna might turn his attention her way.

After a few days of indulgence—

Setsuna sat in the control center, beginning to handle and plan official matters.

Shwoom—

He first opened the stats interface.

[Civilization Overview]

[Civilization Type: Technological Civilization]

[Development Level: Space Age (Faster-than-Light)]

[Territorial Reach: Star Systems (12)]

[Population: 36.557 million]

[Species: Humans, Shipgirls, Sirens, Dragons, Catgirls...]

”...”

Compared to just after breaking the light-speed barrier, the population had nearly doubled.

The combined number of Bulins and Angeloids had surpassed 30 million.

For an interstellar empire, it was still relatively underpopulated.

But with Bulins and Angeloids being extremely efficient workers, it was still manageable.

As for territorial extent...

For interstellar civilizations, territory was calculated by star systems.

Setsuna opened the map.

Within a 20-light-year radius of the Solar System, all star systems with development potential had been equipped with stellar outposts.

Resources were being steadily developed.

Twelve star systems only counted as the very beginning, but fortunately, reconnaissance fleets had detected no signs of alien civilizations within a few thousand light-years.

They could afford to expand step by step.

”Hmm… our Bulin and Angeloid production speed is still a bit slow.”

Setsuna thought a bit more.

”Thirty million Bulins and Angeloids sounds like a lot, but scattered across dozens of star systems and various planets, it’s clearly not enough.”

”From now on, all resources in the starbases should go toward building more Bulins and Angeloids.”

”Understood.”

Yat Sen nodded.

Constructing the Juggernaut had consumed an enormous amount of resources from the empire and its vassal states—it was time to recuperate and ramp up agricultural production with more Bulins.

Next, he opened the extra-dimensional star map.

Out of the five neighboring worlds discovered last time, the Uma Musume world and Kancolle world had already been conquered.

Only Trisolaris, Konosuba, and Madoka Magica remained.

”Hmm...”

Setsuna examined them one by one.

Having just completed FTL retrofits, now was the perfect time to bully a native civilization still incapable of faster-than-light travel.

And it would serve as a trial run for the fleet.

...

An hour later—

In the capital, at the administrative center.

Inside the war room sat shipgirls, Spirits, Heroic Spirits, and other companions preparing to enlist for the expedition.

”This time, our expedition target is the Trisolaris world.”

Setsuna projected relevant information about the Trisolaran world onto the screen.

Richelieu and Yat Sen passed out supporting reference materials to the shipgirls.

Back when the world was first discovered, several shipgirls with a passion for otherworld expeditions had already done their homework.

They had read the original novel cover to cover multiple times.

Including the clumsy animated adaptation, and various wildly modified film versions by different directors.

As a classic of science fiction literature, Setsuna was more than familiar with The Three-Body Problem.

Its core plot revolves around the conflict between humanity and the Trisolarans, who reside four light-years away in the Alpha Centauri system.

The two sides clash over hundreds of years, exhausting every method to destroy each other.

In the end, both humans and Trisolarans are wiped out by a higher alien force—the Dark Forest strike. Mutual annihilation.

From it emerges a fascinating concept:

The Dark Forest Theory.

Its derivation is long, based on two universal axioms proposed by Ye Wenjie and the chain of suspicion, but its core idea is simple.

Put simply: once a civilization is discovered in the universe, it will inevitably be attacked by others.

Therefore, spacefaring civilizations must hide their existence and avoid exposure at all costs.

”Uh... I don’t think the Dark Forest Theory applies to us,” Belfast tilted her head.

”After all, the Commander can conduct interdimensional diplomacy. If we meet aliens, we can talk. If not, then we talk with our fleet.”

”Exactly. For FTL civilizations, the Dark Forest Theory isn’t worth much.”

Setsuna nodded.

In the Stellaris era, civilizations usually greet each other upon contact.

If they can trade and sign non-aggression pacts, great. If not, it’s the usual insult–rival–declare war combo. Then they fight it out properly.

...

Everyone carefully read through the data again.

Their main focus was on the opposing side’s tech level. Since both were spacefaring civilizations, a fleet battle was inevitable.

”Hmm… the Trisolaran world’s technology is quite advanced. They weaponize physical laws to attack enemies—it’s unbelievable…”

Yat Sen spoke with measured tone.

”Dual-vector foil… I never imagined a weapon like that could exist.”

The dual-vector foil is a weapon encapsulating a 2D spatial field, capable of collapsing 3D space into 2D—a dimensional reduction strike.

Nothing can survive having its dimensionality reduced.

In a sense, it is the most thorough and extreme way to kill an enemy.

But it comes with obvious side effects.

A collapse from 3D to 2D never stops. If used recklessly in the universe, eventually the entire cosmos would become two-dimensional.

In ancient times, the Trisolaran world was once an eleven-dimensional realm.

Through dimensional-reduction warfare, it was beaten down level by level to its current 3D state—and still tends toward collapse.

”Get one back for research, but don’t use it in our universe.”

Setsuna succinctly laid out the plan.

”Huh? Doesn’t that mean we’ll have to face the Singers and their parent civilization? Wasn’t it called the ’Homeworld’?”

Several smaller shipgirls were startled.

”What’s there to fear? I still want a shot at the Resetters.”

Grey yawned lazily.

”The Trisolaran world’s tech is indeed deep. Even I couldn’t find anything like the dual-vector foil in the Creator Database.”

”Photon flares and slow-light black domains are interesting too. Turning mathematical laws into weapons? That could probably cripple an enemy’s basic sciences…”

”We’ve gone far enough with conventional weapons—it’s time to master some law-based ones.”

Setsuna strongly agreed.

Back during exchanges with the Synapse people, he realized that whether it was science or magic, all civilizations ultimately pursued the same goal:

To reshape reality through will.

The Trisolaran world happened to fill a gap in that research.

”Wait, the Resetters?!”

Even more shipgirls were startled.

”Aren’t they part of the Trisolaran universe’s background lore? Some god-tier civilization? Are you seriously planning to confront them?”

...

Grey propped up her head and stared blankly at the flustered shipgirls.

”I’m also a fusion of god-tier civilizations, okay? Don’t underestimate nanomachines!”

”And do you remember what Kayo Senju said when we underwent FTL modifications?”

She stood and spoke slowly:

”Beneath the speed of light, all are ants.”

”There’s a qualitative gap between FTL and sub-light civilizations. Their tech is forever capped by the speed-of-light barrier.”

”Whether it’s photon flares or dual-vector foil… No matter how bizarre their weapons are, their delivery and detection methods can’t surpass light speed.”

The more perceptive shipgirls immediately grasped her meaning.

No matter how powerful a dual-vector foil is, it can’t catch an FTL starship.

With advanced sensors, hyperspace, and warp engines, the enemy wouldn’t even touch them.

Meanwhile, with tachyon spears, focused arc projectors, and the Fallen Star Lance, they could obliterate enemy fleets and homeworlds in an instant.

All martial arts ultimately bow to speed—in the space age, the rule still holds.

”So, to us, the Trisolaran world are all just natives.”

Grey nodded.

”More precisely, they’re natives with some interesting black tech and a bit of muscle.”

”This time, we march from the bright savanna… into the dark forest.”

—

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