Crossover Shipgirls: Building a Dimensional Empire from Scratch

Hum—

After satisfying the Siren girl’s small request, Setsuna brought Schwi and descended onto the lunar research base.

This time, those who came to greet him were Einstein, Vill-V, Tesla, and a group of scientists from the Honkai world.

Perhaps because they all originated from the same world and shared some mysterious connection and tacit understanding, they had quickly banded together and focused on a single direction of research.

”Commander, we actually planned to explore the Honkai universe long ago. Mm... it was shelved for various reasons at the time.”

Inside the laboratory, Einstein projected a vast array of complex data.

”After Professor Vill-V joined us, our engineering research related to Honkai made breakthrough progress. Mm... come to think of it, Cosmic Juggernaut was originally built by her.”

Beside her, the green-haired girl with pink eyes and a gear-shaped hair ornament looked extremely proud.

She had joined later than Einstein and Tesla, yet had still secured a leadership position through sheer ability.

”Ah—no wonder that thing felt so aligned with my aesthetic. The world truly is marvelous.”

”Given the Starsea Empire’s current technology, its original form was a bit lacking, so I made a few upgrades to that big fellow.”

Vill-V sighed softly.

Facing a creation made by another version of herself felt somewhat strange.

But the current Vill-V was the Promax version—armed with advanced interstellar-era knowledge and assisted by Bulins, practically omnipotent in engineering.

She tapped a few times on the star map before them, selecting the Solar System.

”In short, the Solar System of the Honkai world is an isolated island within the universe, wrapped in imaginary tides.”

”Its scale far exceeds that of Solar Systems in other universes. Without external influence, civilizations within it have difficulty breaking out.”

”Even the Previous Era couldn’t leave. The Ark simply couldn’t exit the Solar System. Unless one possessed space-warp technology—but reaching that technological level would generate Honkai powerful enough to directly destroy the world.”

”...Ahem, I’m getting off track.”

Vill-V cleared her throat and drew a line across the star map.

”We’ve modified Cosmic Juggernaut slightly, granting it the ability to break through the imaginary tides. It can now freely explore that universe.”

As she spoke, she pointed downward.

The research tower stood at an elevated position. Looking down, one could see a train with a distinctly steam-era aesthetic parked in the open space below the Engineering Division.

Its size wasn’t large—roughly comparable to a small destroyer. The locomotive had been refitted from Cosmic Juggernaut. While retaining its original appearance, it now bore additional modern technological enhancements.

”Uh... your design sense is still as... unique as ever.”

Formidable couldn’t help feeling that Vill-V’s aesthetic differed somewhat from the rest of the Starsea Empire.

”Thank you for the compliment! Commander, it’s wonderful that you didn’t cut my budget!!”

Vill-V puffed out her chest and gave a theatrical bow.

She expressed sincere gratitude toward Setsuna for providing sufficient funding.

”By the way, couldn’t our fleet just directly warp out?”

”Of course we could. But aren’t we heading out to search for more intelligent civilizations? Wandering aimlessly would be meaningless.”

Einstein paused briefly and marked a location.

”We have another discovery.”

”Honkai-1 Space Station has been continuously observing that universe. Based on sensor feedback, we believe there’s a high probability that intelligent civilization exists near this nebula.”

”The cosmic microwave radiation from this direction differs entirely from the blank background noise of other sectors. Preliminary analysis suggests multiple intelligent civilizations—and they likely have already reached the space age.”

They carefully explained the technical details to Setsuna, and incidentally gave Gudako and Jibril a crash course.

For example, the great principle of reversible detection—if one’s technology is sufficiently advanced, one can deduce the entire structure of a civilization from the activity trajectory of a single spacecraft.

And how signals captured by sensors could be used to infer the technological level of alien civilizations within a star region.

The barrage of advanced astronomy and astrophysics left Gudako and Jibril completely dizzy.

Setsuna simply chuckled.

He knew exactly what awaited beyond the Solar System in the Honkai universe.

—They would walk straight onto the stage of a certain Stellaron spirit.

”Alright. Does this new creation have a name?”

”Mm... not yet.”

Vill-V stroked her chin thoughtfully.

”Since it will travel through the starsea and takes the shape of a train... how about we call it the Astral Express?”

”...I knew it.”

Setsuna sighed.

”What about the first expedition team?”

Formidable asked.

”Will we draw members from each fleet, or will you personally lead it, Commander?”

”Well...”

Setsuna pondered for a moment.

”Let the Imperial Valkyrie Academy handle it. Consider it their social practice activity.”

”Didn’t they get a bit frightened during their first trip to space? This time, let them go out and see the world. It’s professionally relevant, after all.”

”I plan to take some time to visit other worlds.”

Because teleportation anchors had been placed within the Honkai universe, he didn’t need to personally tear through space.

Exploration on both sides could proceed simultaneously. If any problems arose, they could simply call for reinforcements from the homeland or summon the fleet.

”Oh—”

Gudako poked Setsuna and leaned closer.

”Wait, Commander, I just came up with a super, super, super interesting idea.”

”Go on.”

”Your authority can open a passage from one world to another, right? It doesn’t have to originate from our native world, does it? I was just thinking—the Magic Gods over in that certain world are bored out of their minds...”

She traced two lines across the star map.

”Oh? That’s true.”

Setsuna nodded.

Although he usually opened passages from the Starsea Empire’s homeworld, the exit point was ultimately determined by him.

Doing so was merely convenient for mobilizing personnel.

”Then let’s change our perspective. In the Star Rail universe, you open a passage to the Magic Gods’ world. Lure the Magic Gods over to fight the Aeons—an imperial capital showdown.”

”Then we run away, sit on the sidelines eating popcorn, and come out afterward to clean up the battlefield. Wouldn’t that be hilarious?”

Gudako looked like she had discovered a new continent, her face brimming with excitement.

”Ah, a classic tactic of driving the tiger to devour the wolf...”

”...”

Setsuna fell silent for a moment before patting Gudako’s head.

”You really are a little genius. I’ll have to make you the Aeon of Elation someday.”

...

Within the capital of the Starsea Empire, inside the Imperial Valkyrie Academy.

Theresa stepped onto the podium. Himeko thoughtfully adjusted the extendable base beneath it so Theresa would appear taller and not be hidden by the lectern.

She swept her gaze across the Valkyries gathered in the auditorium.

”Everyone, under the Commander’s orders, we are about to conduct a social practice activity.”

”The Imperial Valkyrie Academy will select a group of outstanding Valkyries to board the Astral Express and carry out exploration of extraterrestrial civilizations.”

”Mm... according to the Commander and the Research Division, that universe contains many intelligent civilizations that have already entered the interstellar era.”

”We will explore the unknown starry skies for the Starsea Empire, understand unknown civilizations, and connect new worlds.”

”Waaaah!!!”

The hall immediately erupted in commotion.

The Astral Express. The first cosmic exploration. Searching for interstellar civilizations.

The combination of these elements was simply too exhilarating.

Ever since transferring from St. Freya to this academy, they had attended classes for so long. Finally, they had a proper expedition opportunity!

For a time, the chatter was endless.

”Are we going with the fleet? Or acting independently? ...”

”Do we have intel? Will there be combat? What level are the enemies? ...”

”How far is it from us? How long will it take?”

”Alien civilizations? What do they look like? Like the Trisolarans? ...”

”...”

Theresa patiently answered each question.

”This is an extracurricular training activity organized by the academy. We will serve as the vanguard force for this cosmic exploration. Please cherish this opportunity.”

”...As for combat, there is no need for concern. If you encounter opponents whose rank clearly exceeds your own, reinforcements will arrive.”

”Our primary mission is exploration, not conquest or warfare. Mm... think of it as an adventure team.”

”Gasp...”

The crowd below boiled over once more.

Countless girls raised their hands, scrambling to sign up.

”Me, me, me! I want to go!!—”

”Take me with you, Himeko—ah, I mean, Himeko-sensei! Himeko-onee-san!!”

”We will select outstanding students to participate in this exploration activity. Those interested should submit their applications promptly.”

Seeing everyone’s enthusiasm, Himeko felt deeply gratified.

Sure enough, after staying in the Starsea Empire long enough, one inevitably yearned to explore the stars and the unknown.

”Ah...”

Mei, Bronya, and the others suddenly felt a strange sense of déjà vu.

”Why does this speech feel so familiar...?”

”Ah!!!—”

Mei slapped her thigh.

It felt like returning to their days at St. Freya, when Earth first ventured into space.

After an impassioned speech, they had boarded the spacecraft full of confidence—only to collide with a space station and Eternal Snowfall the moment they broke through the atmosphere.

They had then discovered they were being subjected to an extraterrestrial father figure’s sociological +8 buff in the most merciless fashion.

Fortunately, now the extraterrestrial overlord was themselves.

...

The Starsea Empire’s hardcore extracurricular practice activity sparked an unprecedented registration frenzy within the Imperial Valkyrie Academy.

The entire academy rushed to sign up, all hoping to board the Astral Express.

Applications flooded Theresa, Himeko, and the others’ inboxes like falling snow.

However, the slots were ultimately limited. The list for the first expedition would be finalized by the academy before being submitted to Setsuna.

”Ah...”

Inside the academy office, Himeko, Shigure Kira, and several other instructors gathered together.

They reviewed the students’ applications while discussing the final selection.

”This expedition still requires a teacher to lead the team. I’ll remain at the academy to continue overseeing teaching duties, so Himeko and Shigure Kira, I’ll leave it to you.”

Theresa smiled with mature composure.

Though she looked like a little girl, as the academy’s principal, she was unquestionably everyone’s senior.

”Mm, understood.”

Himeko poured herself a glass of wine, took a sip, and flipped through the student list page by page on the holographic interface.

Every application was written with heartfelt sincerity.

”I have studied in the Starsea Empire for a considerable period and have proficiently mastered the various skills taught at the academy. My Hokushin Itto-ryu techniques have improved greatly, and I have obtained certification as a junior starship pilot... I hope to temper myself through this journey...”

”—Applicant: Raiden Mei.”

”Mm.”

Himeko agreed without hesitation.

”Raiden Mei has ranked first in every exam. Her overall strength is outstanding. It’s only natural for her to participate in this pioneering mission.”

”Approved.”

”Bronya has interned in the Engineering Division and the Physics Division, attended Professor Vill-V and Professor Einstein’s lectures, and wishes to travel farther...”

”Attached: Internship results and certificates.”

”—Applicant: Bronya.”

”Mm-hm.”

Himeko nodded again.

Bronya was also a genius within the academy. With endorsements from Einstein and Vill-V, her capabilities were beyond doubt.

Without much deliberation, she added Bronya to the list.

”Herrscher of Sentience? She isn’t under our jurisdiction. She can go find the Commander herself...”

”Pardofelis? Hm? ...”

Then she saw another application.

As she read, her expression gradually turned strange.

”Shigure Kira, how are Kiana’s evaluation results?”

”Huh?”

Shigure Kira checked.

”So-so. That kid’s a bit playful. She’s pretty good in astronomy and combat courses, but her language, biology, math, and such aren’t great.”

”Maybe the academy curriculum is a bit intense? She doesn’t seem to like theoretical classes much.”

Under Cecilia’s influence, the white-haired dumpling wasn’t as disastrous as before, barely scraping sixty across five subjects combined.

Unfortunately, her slightly airheaded personality hadn’t changed.

”Is there a problem?”

”Here.”

Himeko forwarded Kiana’s application.

Shigure Kira subconsciously began reading aloud:

”My Commander father often teaches me that our goal is the vast sea of stars...”

”???”

She nearly lost her composure at the very first sentence.

”In order to become the strongest Valkyrie and make Dad proud, I want to adventure across countless worlds like him and plant the flag of the Starsea Empire in every corner of the great universe...”

”Although my grades aren’t very good, I will definitely protect Raiden Mei, Bronya, and my companions! I’m really strong in fights! ...”

At the end, she even drew a cutesy emoticon.

”...”

Himeko, Shigure Kira, and the other instructors exchanged looks.

Kiana’s words were heartfelt, yet all they could see were seven characters: ”my Commander father.”

”Uh...”

Himeko paused.

”Kiana, you’ve truly achieved invincibility.”

...

”Commander, I’m going on a long journey!!—”

Not long after.

The lively white-haired dumpling hurled herself into Setsuna’s arms.

Cecilia gently stroked Kiana’s head with a warm expression.

”Don’t push yourself when you run into trouble. If you can’t handle something, just call the Commander.”

Radiating maternal warmth, she carefully reminded Kiana.

”Got it—!”

Kiana leaned against Setsuna’s chest, tracing circles on him with her finger.

”Commander, if we run into aliens, what should we do?”

”Think more.”

Setsuna took a sip of tea and replied.

”Mm...”

Kiana seriously recalled the history of the Starsea Empire.

It was her first time traveling so far. She was excited—and a little nervous.

”Then... after thinking?”

”Still think more.”

Setsuna pinched her cheek.

”Mm...”

The white-haired dumpling pondered for a long while before suddenly lighting up in realization.

”Oh!!”

”I get it! I should bring lots of girls back for Dad!!!—”

”Don’t worry, I’ll accomplish it!!”

”Huh?!”

Cecilia nearly stumbled.

”Kiana, wait just a moment...?”

...

A few days later.

At the Honkai Space Station, a small team boarded the Astral Express.

”Phew, good thing I was selected. Otherwise I’d have to take Dad’s Eternal Snowfall to explore the universe.”

Kiana looked utterly relieved.

”???”

Raiden Mei stared at her as if she’d seen a ghost.

”What is with that whole ’if my startup fails, I’ll just go home and inherit a company and billions in assets’ vibe, huh?!”

”Kiana, there’s now a tragic thick barrier between us.”

Bronya added dryly.

”Nooo! Riding the Astral Express is way more fun!!”

The three joked around for a while before Vill-V cleared her throat, finally restoring order.

Together, they looked up at the massive construct before them.

”Whoa—”

Viewed up close, the Astral Express possessed a unique aesthetic beauty.

The locomotive appeared to follow a steam-era design, yet it was fully enclosed, every component forged from high-performance alloys.

”The Astral Express is equipped with a high-output Klein Field and energy shields. Under overload conditions, it can withstand a direct strike from a planet-destroying weapon.”

”It also contains magical interference systems to effectively prevent teleportation spells from boarding the train through jump assaults.”

Vill-V, Tesla, Einstein, and the other Honkai scientists guided the team through each module of the Astral Express.

”It’s huge!!”

Raiden Mei realized that the interior space was noticeably larger than the exterior suggested.

The train contained a fully functional ecological circulation system. While it couldn’t compare to Eternal Snowfall or Titan-class warships, it was still quite spacious.

”Considering the length of your journey, we expanded the living quarters as much as possible.”

”If you encounter emergencies, contact us. The Starsea Empire will dispatch reinforcements in the shortest possible time.”

Tesla patted Kiana on the shoulder.

”Additionally, two Angeloid combat squads are stored in the rear section of the train. They are currently in dormancy. Deploy them if necessary.”

”Don’t worry, I can handle it!”

The white-haired dumpling radiated confidence.

She patted her backpack, stuffed with numerous Starsea Empire specialties—magic scrolls and various odd gadgets.

Led by Himeko, with Mei, Bronya, and the others seated in place, the team prepared for departure.

”Then this time, we shall serve as the Starsea Empire’s vanguard in exploring the universe.”

Himeko straightened herself.

She selected the predetermined coordinates on the star map.

”Commander, await our good news~”

”Once we discover alien intelligent civilizations, we will report immediately.”

Half an hour later, all preparations were complete.

Hum—

The Astral Express slowly departed from the space station.

It accelerated—and accelerated further—within the vast, boundless cosmos.

Like a silver meteor, it pierced through the barrier enveloping the Solar System and vanished among the distant stars.

”Starsea Empire Vanguard Squad—depart!”

Inside the carriage, everyone gazed out the observation windows and burst into cheers.

”—Though this journey stretches far, it shall ultimately reach the stars!!”

—

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