Crossover Shipgirls: Building a Dimensional Empire from Scratch

Led by Grey, everyone surrounded Setsuna, who had just acquired a new power, engaging in a brainstorming session.

”What’s the point of a Dyson Sphere besides looking cool?! Can’t you just conjure an Aetherophasic Engine and a Synaptic Lathe instead? That’d save the Bulins a lot of trouble!”

Gudako raised her hand.

”The Galactic Wonder at stellar scale is too much work, too unrealistic. Let’s lower the difficulty—maybe a Sentry Array or a Matter Decompressor?” Formidable said, arms crossed.

”???”

Setsuna realized none of these girls were easy to deal with.

Only Tesla, Einstein, and the other scientists who had just arrived looked utterly confused by the conversation.

”Dyson Sphere? That thing where you build solar panels around the Sun? Why would you need that? Isn’t a dark matter reactor more advanced? ...”

”For fun, and because it looks nice.”

Grey’s reply was short and to the point.

”Ah? ...”

Einstein didn’t quite understand but decided it must be some strange hobby of these interstellar overlords.

”Can you make a reasonable request?”

Setsuna rubbed his temples.

”This is for stress testing,” the nanobot explained righteously.

”The Herrscher of Reason’s Core, in theory, can reproduce anything from the Honkai world—including the Divine Keys.”

”The Commander’s power is several magnitudes above a normal Herrscher. Naturally, he should be able to do even more.”

The group of little girls all nodded vigorously.

”Makes sense! Ordinary Herrschers are limited to creating Divine Keys or ships, but the Commander should be capable of greater things!”

”...Alright then.”

Setsuna decided to give it a try. He was curious to see the limits of his ability as well.

He extended his hand toward the void.

Whoosh—

A massive surge of energy gathered in his palm.

Through the porthole, in the distant starlit void, a strange object began to take shape—its form uncertain, its composition unknown.

It looked like a mass of liquid metal, constantly shifting its form.

This was his first time using the ability, so he wasn’t yet proficient, gradually getting used to how the power responded to his will.

Minutes passed, and the mysterious structure slowly twisted into the shape of a gigantic space city.

Hundreds of kilometers long, with four-winged architecture and an enormous antigravity device beneath it, the sight made the girls cheer in excitement.

”Ohhhhhh—!”

”That’s a research hub!!! Commander, can you make the research wings bigger? ...”

Although smaller than the Galactic Wonder currently being built in the capital, its overall form was now visible.

”Hmm...”

Just as they watched the shape of the scientific hub take form, fine-tuning its details bit by bit—

Suddenly.

Crack—

Setsuna lowered his hand. The half-finished megastructure shattered instantly.

The colossal energy dispersed into countless motes of starlight, fading into the vacuum.

”No good.”

Setsuna shook his head and pressed his temples.

”Commander, what happened?”

Formidable, Belfast, and several shipgirls crowded around with concern.

”Two issues. First, constructing a Galactic Wonder from scratch consumes an enormous amount of energy.”

”Second, have you forgotten the condition of the Herrscher of Reason’s authority? You must fully understand an object’s structure before reproducing it.”

”This ’understanding’ refers to attaining a complete abstract comprehension—then using Honkai energy to reconstruct order in reverse.”

Setsuna sighed.

”Isn’t it a bit unrealistic to expect me to fully understand the structure of an interstellar-era megastructure?!”

As Commander, he was responsible for the Empire’s grand strategy, not the intricate technicalities of research.

Those were handled by the Science Division, Engineering Bureau, and various departments. All he needed to do was issue directives, provide materials or data, and wait for results.

To him, those megastructures were basically black boxes.

”How about you go take some classes? Learn more?”

Gudako was still unwilling to give up.

Bonk—

Setsuna knocked her on the head.

”You think starting from scratch and studying until I fully understand the composition and operation of a Galactic Wonder would take how long? If you think it’s so easy, you try it.”

”Guu...”

Everyone looked rather disappointed.

”So we can only make boring little trinkets from now on? What a waste.”

”You still need to study, Commander. You have to learn physics, engineering, and other sciences from scratch—just like the original Herrscher of Reason...”

As the girls chattered on—

Belfast suddenly raised her hand.

”Come to think of it, the Eternal Snowfall comes with built-in data processing capability...”

”If it’s unrealistic for the Commander to fully understand the structure of every object, why not leave it to the shipboard AI? The Juggernaut AI should be able to analyze most things, right? ...”

”?!”

Setsuna and the others froze for a second.

”Ah, that’s right! I’m technically the same entity as the starship, aren’t I?”

”Alright then—let’s go, technology!”

...

A few minutes later, Kayo Senju handed Setsuna a small storage device.

”Commander, this contains several of our starship’s design schematics. Let’s test it out first?”

”Got it.”

Click—

Setsuna uploaded the contents into the Eternal Snowfall.

Then, standing on the bridge, he extended his hand once more, invoking his authority.

Hum—

The ship’s main console processors began to emit a low vibration.

[Data analysis in progress... Analysis complete.]

A holographic interface projected before Setsuna. The shipboard AI had instantly decrypted the stored data.

It transmitted every structural detail directly to him.

In the distant void—

Whoosh—

A silver-white starship, hundreds of kilometers long, began materializing from its bow—constructed seamlessly from front to back, like a colossal 3D print.

Not only its hull, engines, and propulsion systems, but even the minute interior details—the tables, chairs, coffee machines, drink dispensers, cups, toothbrushes, and towels—were perfectly reconstructed.

Every bit of data was precisely transmitted to Setsuna, then reproduced flawlessly through the Herrscher of Reason’s authority.

The Juggernaut AI could analyze material structures down to the molecular level—absolutely rigorous, absolutely accurate.

In the strictest sense of the word, it was complete understanding.

Before long—

The Starsea Empire’s standard-class battleship appeared not far away.

”Whew—”

Completely creating a starship from scratch had taken some effort, but it worked.

”Whoa...”

”How convenient?!”

The little lolis and the newly arrived scientists were dumbstruck.

Taking a shuttle, they boarded the newly conjured vessel.

The interior was identical to those built in the Empire’s shipyards, down to the last detail. Even the armaments—photon lances, erosion missiles, and other technologies beyond the Honkai world—had been faithfully reproduced.

Not a single screw differed from the design.

”~Hiss...”

Einstein, Edison, and the others were amazed.

They had researched Honkai energy for years back on Earth, but this was the first time they had seen someone master a Herrscher’s authority so quickly—and wield it so effortlessly.

”Speaking of which, if the Herrscher of Reason wanted to destroy Earth, couldn’t he just create a warship like this and bombard the planet?” Tesla suddenly asked.

”No, he couldn’t.”

Kayo Senju shook her head.

”This ship took us a very long time to design. Without AI support, I don’t think any ordinary person could fully comprehend its structure and mechanisms through their own effort.”

”For the Honkai world, this level of technology belongs to the realm of the future.”

The Herrscher of Reason’s replication authority required one thing above all—understanding.

Even the simplest starship incorporated technologies from multiple worlds. Its construction was anything but simple.

”Still, having the ship AI assist with analysis makes things much easier...”

Setsuna stroked his chin thoughtfully.

He tapped a few icons on the holographic interface, sending a batch of strange data into the starship’s database for analysis.

Whoosh—

He stretched out his hand and conjured a classic AK rifle.

Energy shifted in his palm—then transformed into several Angeloid portable gamma laser weapons, space fighter crafts, and combat drones.

Creating these smaller things required little effort; as long as the data was in the database, he could construct them with a mere gesture.

It was like playing in creative mode—and he was thoroughly enjoying it.

”Commander, Commander, can you make food, nanoda?” Yukikaze asked, ears twitching.

”Of course.”

Whoosh—

Setsuna conjured a lollipop and a coolant drink for her, then tossed a bottle of Vodka to Gudako.

Both the formula and the flavor were identical to the originals.

”???”

The shipgirls and the other girls stared as Setsuna continuously pulled out all sorts of bizarre creations from thin air like a magician.

Before long, the main control room floor was piled high with random items.

”This ability’s way more fun than the Herrscher of Corruption’s. All I need to do is feed the design data into the ship’s computer and let it calculate the rest.”

Setsuna grinned.

”Amazing—I’m starting to understand everything.”

...

The construction of the Galactic Wonder was temporarily set aside—it was far too complex, and the energy requirement too immense for the shipboard AI to process in a short time.

After a series of tests, Setsuna discovered that the Herrscher of Reason’s authority allowed him—and by extension, the Eternal Snowfall’s Juggernaut AI—to analyze and replicate almost anything.

In fact, if he wanted to, he could create an entire fleet without limitation.

Whoosh—

In the vastness of space—

Dozens of starships appeared in perfect formation.

They were smaller than the previously created battleship and stripped of nonessential components like command decks, bedrooms, and kitchens—leaving only the core structure, engines, thrusters, and combat systems.

With the experience from his first attempt, Setsuna had grown familiar with the Herrscher of Reason’s authority, and the construction process was completed almost instantly.

Whoosh—

The starship group darkened the void. Black and crimson space fighters were also produced, hundreds of them circling like a swarm.

The entire fleet operated purely under Setsuna’s mental control.

With a single wave, they arranged themselves into a battle formation.

Their primary axial weapons and countless massive turrets gleamed ominously, inspiring awe and dread.

”Is this... infinite fleet production?!” Gudako gaped in disbelief.

She could see clearly—those ships didn’t match any known class within the Starsea Empire. They were Setsuna’s original creations.

More precisely, they were pure weapons of war, not mere reproductions like the previous battleship.

”The Herrscher of Reason’s authority is an abstract concept. Understanding the structure of a starship isn’t difficult for me—I am a starship myself.”

”In that sense, doesn’t that mean I alone can serve as an entire fleet?”

Setsuna clenched his fist.

In the original storyline, during the Second Honkai War, Welt Yang had used Honkai energy to manifest a massive fleet to battle Sirin.

Even after his fleet was destroyed, he repeatedly reconstructed both ships and weapons.

The creations Setsuna could manifest were far more advanced than Welt’s—Starsea Empire’s technology was on a completely different level compared to 21st-century Earth’s.

With the aid of the Wisdom Cube, Allspark, and other power sources, his output limit far surpassed that of an ordinary Herrscher.

”Fascinating...”

Einstein, Planck, and the other local scientists, after their initial shock, quickly fell into an ecstatic joy—like explorers discovering a new continent.

A new Herrscher! One who simultaneously possessed two Herrscher Cores, his strength vastly exceeding any conventional Herrscher!

They looked at Setsuna with gleaming eyes, as though he were the perfect test subject.

If not for the fact that he was the Supreme Commander of the Starsea Empire, they would’ve dragged him straight into the lab for experiments.

”Hm... as expected, it’s just like the Herrscher of Corruption’s Core. In the Commander’s hands, its power is exponentially stronger. The Herrscher of Reason’s Core works the same way,” Kayo Senju nodded knowingly.

”We’ve theorized that the Herrscher of Reason’s abilities have three defining traits: infinitude, efficiency, and absolute control.”

”First, its potential is virtually limitless—it only depends on how much Honkai energy the Herrscher can access. As long as the Herrscher lives and doesn’t exhaust their energy, they can endlessly create.”

”Second, the construction process is extremely fast. As the Commander just demonstrated—once proficient, there’s practically no downtime between conception and completion.”

”Lastly, the Herrscher of Reason has absolute control over everything they construct. No pilots are required for operation.”

She paused briefly.

”Of course, the Commander can also rely on the ship’s computer for assistance. After all, controlling thousands of ships simultaneously by sheer thought would be... taxing.”

Once again, everyone witnessed what it meant for sheer power to defy reason.

With a mere wave of his hand, Setsuna could project thousands of starships across the galaxy—one man equaled an entire armada.

”Hm...”

”This authority seems to utilize concentrated Honkai energy within the body to reverse-engineer order, producing objects of negative entropy...” Einstein murmured, lost in thought.

”Besides mechanical constructs, can you also create organic life and other Honkai-related structures?”

”Yes.”

Setsuna nodded.

”I can even reconstruct my own or someone else’s body—though that’s rather pointless. I’m one with the starship; I don’t need any extra enhancement from the Herrscher of Reason’s authority.”

”The Life Sciences Division is far more specialized in that field.”

”Though perhaps one day, I could modify the Eternal Snowfall myself...”

Once familiar with structural composition, he realized he could upgrade his own ship body.

”As for Honkai-related structures... I recall that the Herrscher of Reason’s authority can construct Divine Keys. If you give me the blueprints, it shouldn’t be too difficult.”

He gestured for Kallen’s weapon.

The Science Division had long since studied the structure of Divine Keys, with detailed experimental reports and schematics.

Whoosh—

An identical massive cross materialized before them, leaving Kallen completely stunned.

”Theoretically, this copy should possess similar functions. However, since its core isn’t a genuine Herrscher Core, it can’t establish a connection to the Imaginary Space.”

Setsuna shrugged.

”These constructs rely on my own power to maintain, so they’re still somewhat different from the originals.”

”That’s already ridiculously impressive, thank you very much...”

”Too damn absurd,” Gudako couldn’t help but mutter.

If the Herrscher of Reason on Earth was still bound by the limits of their Honkai energy capacity and the scientific knowledge of terrestrial civilization, then Setsuna was free from all such constraints.

With the Starsea Empire’s immensely advanced technology, his overwhelming power, and the shipboard AI’s efficient processing capabilities, the Herrscher of Reason’s authority reached near-infinite potential.

Its value far surpassed that of the Herrscher of Corruption’s power, which he once used to create Honkai Beasts or bully Senti.

”Not enough. Someday, when I can conjure a Wonder or forge an entire star system barehanded, then we’ll talk.”

Setsuna decided to think on a grander scale.

”With enough strength, all impossibilities become trivial.”

”...”

The newly acquired Herrscher of Reason’s authority sent the ship’s scientists into a frenzy. They dragged Setsuna into endless experiments, day after day.

The newly recruited Honkai scientists, despite their brilliance, found themselves overwhelmed. They wished they could split into multiple selves—one to study interstellar technology, another to research the Commander himself.

After only a few days, they were already completely immersed in the ocean of new knowledge and technology.

”When can we visit the Starsea Empire?!” Planck and Einstein were practically bouncing with excitement, eager to witness the full splendor of a super-civilization.

”Stay aboard for now,” Setsuna replied with a faint smile. ”Once we’re done with this temporal node’s objectives, we’ll proceed to the next one.”

He activated the transdimensional starship.

Hum—

The vessel unfolded into higher-dimensional space, the hull trembling softly.

Outside the porthole, the darkness of space was replaced by a swirling realm of chaotic, prismatic light.

”Ohhhhhh—!”

The native scientists were awestruck, as though witnessing divinity.

To enter higher dimensions—to travel through time itself—was something beyond even theoretical comprehension for them.

BOOM!!—

[Three-dimensional spatial coordinates have been converted to higher-dimensional temporal coordinates.]

With the AI’s prompt, the navigation display shifted from a star map to a chronological chart.

[Current timeline: Year 1951.]

”So, which year are we heading to next?”

Setsuna turned to Grey and the Science Division for input.

After recalling, he remembered that the founding members of the three great families were born roughly forty to fifty years later. The next major historical point would be before the Second Eruption.

”No, no, no.”

Grey shook her head.

”Since we’ve already extracted all of future Anti-Entropy’s scientists and retrieved the Herrscher of Reason, the future is completely different now.”

”Commander, our next jump will be earlier than that—your other wife is about to appear.”

She snapped her fingers and opened an internal channel.

”Attention, Science Division—assemble.”

”We’ve got an important topic to discuss: if the Commander wants to eat oyakodon, how do we ensure that when the mother is taken away, the daughter still ends up existing?!”

”Ah, a truly profound discussion—combining biology, ethics, and higher-dimensional cosmology into one.”

—

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