Crossover Shipgirls: Building a Dimensional Empire from Scratch

In the higher dimensions of spacetime—

Setsuna watched the entire Honkai world with great interest, observing how the worldline had shifted due to his earlier actions.

A butterfly effect.

Ever since the battle of Schicksal ten years ago, when he took away Kallen and the Oath of Judah, and even three thousand years before that, when he helped the ancient Shenzhou ancestors defeat Chiyou, the ripples of these events had begun to alter the trajectory of modern civilization.

According to Grey, they had run full-spectrum simulations of the Honkai world, ensuring that every development unfolded exactly as expected.

”You mean, you’ve already predicted that Otto would acquire that tablet?” Fu Hua asked in surprise.

”Yes,” Kayo Senju replied with a sly smile. ”To be precise, it was deliberately arranged by us. We had the Angeloids tweak a few things, then left a small element of chance. That’s how the tablet ended up here.”

”According to our calculations, this event will steer the Honkai world toward a rather intriguing future—an important turning point.”

Before her, the holographic interface displayed a massive branching tree diagram, mapping countless possible outcomes.

Some showed Otto taking his own life out of despair after failing to find the tablet. Others had him encountering Ma Feima by chance and journeying to Africa to study shamanic rituals...

One scenario even depicted Earth descending into nuclear war five hundred years later, while another saw the Ming Empire accidentally excavating alien technology and unifying the globe.

Each event possessed a precise trigger mechanism.

For example, guiding Otto to Shenzhou in 1487 to discover the stone tablet left by its ancient people would set the Honkai world on an entirely new course five centuries later.

Everything could be solved; the future lay fully within their grasp.

For the first time, Setsuna experienced the overwhelming power of mathematical laws so directly.

With the aid of the transdimensional starship, he could truly achieve what might be called—”control of the future.”

”That’s terrifying,” Fu Hua said sincerely.

Higher civilizations no longer relied on brute technological superiority to crush lesser ones—they could now manipulate and compute their very futures.

”Hmm... what did we decide to call this system for future deduction and simulation again?” The little loli tilted her head, trying to recall.

”Calling it ’Mathematical Law Weapon’ sounds too blunt and boring. Commander, do you have any suggestions?”

”The Grand Derivation Array,” Grey replied without hesitation.

”Doesn’t that name sound both ancient and domineering?”

”...”

Setsuna’s face darkened slightly.

”You and Fu Xuan would get along splendidly. You two could have a contest to see whose predictions of the future are more accurate.”

After a brief sigh, Setsuna turned his gaze downward once more.

Like watching a film, he anticipated how the next scenes would unfold.

As expected—

Otto became deeply fascinated by the mysterious inscriptions on the stone tablet.

He spent vast sums purchasing every similar tablet the merchants had.

Not just the ones Cang Xuan and Dan Zhu had commissioned their ancestors to carve, but any other mural impressions or ancient copies resembling them.

Real or fake—it didn’t matter. He bought them all.

He scoured every antique and painting shop across the city, his carriages overflowing with artifacts.

Shhh—

With a casual gesture, Setsuna shifted the temporal axis again.

The transdimensional ship advanced one year along the timeline.

He watched Otto tirelessly traversing Shenzhou, gathering materials.

Not only did he continue his research on the tablets, but he also sought out renowned masters to study ancient Shenzhou script, trying to decipher the engravings.

Several months later, he finally began his return journey to Europe.

...

Within Schicksal’s headquarters—

Otto held the stone tablet high before the organization’s upper ranks and clergy, announcing his great discovery.

”I believe the Earth is round—and revolves around the Sun.”

”???”

At that, Setsuna nearly lost it.

He smacked his forehead, remembering that European science was still in its infancy at this point.

The religious faction within Schicksal remained dominant—essentially a feudal-era relic.

To them, both the heliocentric and geocentric theories were heresy.

The moment Otto uttered those words, the room fell deathly silent.

Shock rippled through the assembly.

They stared in disbelief at the young man of the Apocalypse family.

Otto presented his findings to the upper echelons of Schicksal with meticulous data and eloquence, detailing the grand discoveries from his journey east.

”Oh, in one of our simulations, there was a possibility that his evidence would be insufficient, and he’d fail to convince the higher-ups—only to be burned at the stake as a heretic.”

”But it seems that’s not the case this time.” Grey shrugged with an unsurprised expression.

As expected—

Although the leaders of the Schicksal Church were shocked, they reluctantly permitted Otto’s astonishing declaration.

Several frowned, seriously pondering the plausibility of his theories.

Next, Otto began presenting the fruits of his expedition to the East.

”Regarding the great battle on the Kipchak Plains twelve years ago, I gathered several records during my travels in the East.”

His attendant delivered the tablets and translated documents to the Schicksal executives.

”That day, our defeat was not at the hands of the Ming Empire’s armies, but by another civilization known as the Starsea Empire.”

”They had already arrived on Earth over three thousand years ago, standing alongside Shenzhou’s ancient ancestors.”

”According to the inscriptions, their starship aided a Shenzhou tribe in 2100 B.C. in slaying a Honkai Beast named Chiyou.”

”Additionally, there are over twenty recorded engagements—each documenting how the Starship helped Shenzhou’s ancestors defeat monsters.”

As they stared at the engraved illustrations on the stone tablet, every Schicksal high priest felt their hearts tremble.

They recognized it instantly—the starship depicted on the tablet was identical to the one that had annihilated their legions twelve years ago.

And among the carvings... was the Immortal Phoenix herself!

The Shenzhou tribes had used their ancient script to record their gratitude toward Fu Hua, Cang Xuan, and Dan Zhu, their names clearly etched among the words of praise.

That Shenzhou immortal and the Starsea Empire had already existed three thousand years ago.

A chilling wave of dread swept through the chamber.

”From the tribesmen’s accounts, the starship told them it hailed from beyond the heavens—from a realm outside the Earth.”

”Which aligns with our own experience twelve years ago when that ship descended from the sky. Thus, the Starsea Empire does not exist on this planet.”

Otto continued his explanation.

Given the 15th century’s level of transportation, even traveling abroad was an arduous feat—Otto’s journey to and from Shenzhou had taken over two years.

The notion of escaping gravity and reaching the stars was utterly beyond comprehension for the people of this age.

Yet they still pondered this impossible truth with utmost seriousness.

”Then what are their weapons and those angels?” asked one of the clergymen.

”Unclear. Most likely constructs of Honkai energy. The tablets do contain mentions of Honkai energy.” Otto replied.

Given the limits of his understanding, concepts like photon lances or artificial intelligence were inconceivable to him.

When in doubt, blame Honkai energy—it was, after all, considered an all-purpose explanation for the inexplicable.

”...”

”The Starsea Empire is a threat,” said a senior member of the Kaslana family after a long silence.

”We have no idea what their intentions are, but their strength far surpasses ours.”

”I believe that ship possesses the power to conquer the world. Even the Ming Empire could not stand against it—let alone us, especially with the Immortal Phoenix on their side.”

”Agreed,” nodded the patriarch of the Schariac family.

”The Starsea Empire has not acted in open hostility. They must have another purpose...”

”To wield such overwhelming power, yet appear only twice—once three thousand years ago, and once twelve years ago... What are they planning?”

”...”

No one had an answer. No matter how hard they tried, the leaders of Schicksal could not fathom the Starsea Empire’s true motives.

”At least now, our research has direction,” Otto declared.

”If the Starsea Empire truly comes from beyond the Earth, then our focus should be the same—to reach beyond the stars.”

”Not only to combat the Honkai, but also to prepare against the threat from beyond.”

He spoke with righteous conviction.

After a brief period of shock and debate, the Schicksal Church agreed.

”Henceforth, all information concerning the Starsea Empire shall be classified as top secret.”

”We must find a way to construct a vessel capable of leaving this world—to see beyond the heavens, and to prepare for any confrontation with the Starsea Empire.”

Even though, at this time, humanity hadn’t even invented the steam engine—let alone ships or aircraft—the sheer impact of Otto’s revelation compelled Schicksal to set an ambitious new goal.

To counter the Starsea Empire—to reach for the stars—and build a vessel that could rival their own.

”Starting the age of the star-faring worldline several centuries early, huh? Impressive,” Setsuna chuckled.

Turning his gaze, he noticed the Ming Empire was also showing signs of similar activity.

After stabilizing the realm, the Emperor had ordered his artisans to find a way to construct flying machines.

Unlike Schicksal, their motivations were purely pragmatic—believing that if they could fight battles in the sky, they would hold an overwhelming advantage in future wars.

”Well, technically speaking, they’re not wrong,” Grey said with a pause.

Setsuna already knew what she meant.

After all, when the natives finally struggled their way into space, only to discover a high-dimensional observation station overhead—

They would find themselves being sociologically observed and analyzed by a civilization with +8 intellect.

Truly, a sight to behold.

Under a series of meticulously arranged coincidences and calculated simulations—

Schicksal established its grand ambition to explore outer space.

For 15th-century natives, such an undertaking was nothing short of extraordinary.

Of course, from the higher dimensions of spacetime, Setsuna could see clearly that Schicksal was far from united.

Each faction had its own goals.

Some among the upper echelons sought to recover traces of Kallen and the Divine Key, still haunted by the losses they suffered over a decade ago.

Others viewed the Starsea Empire as a potential enemy—an existential threat that must be prepared against if Schicksal ever wished to dominate the world.

And then there were those few who pursued the dream purely for the sake of science.

As for Otto, his objective was the simplest of all.

To find Kallen, and uncover the truth of what had happened back then.

”...You’re quite the popular one, half of Schicksal’s forces are looking for you,” Grey remarked, scratching its head as it glanced at Kallen.

”Hmm...”

Kallen puffed her cheeks.

When she had first been brought to the Starsea Empire, she had been utterly bewildered—seeing herself as nothing more than a prisoner of war.

But over time, she realized that this place was nothing like what she had imagined.

From the orbital station, she witnessed how the Schicksal Church oppressed its people—conducting horrific, inhumane experiments in their quest to study the black box and harness Honkai energy.

To deflect the growing unrest, they had launched their so-called ”Eastern Crusade,” invading a distant and powerful Eastern empire.

The feudal kingdoms of the 15th century were not as glorious as they appeared on the surface. Having witnessed the countless atrocities committed by Schicksal, Kallen no longer viewed those so-called holy men as righteous.

The capital of the Starsea Empire—built by little lolis, shipgirls, and Spirits alike—was far closer to a true paradise on Earth.

”I think they should hurry up and join the Starsea Empire... what was the term again... a vassal state?” Kallen said after a moment’s thought, her expression serious.

To her, becoming a vassal state under the Starsea Empire was the most promising future a native civilization could hope for.

Though the ruling elites would inevitably be purged, the lives of the common people would improve drastically with technological progress.

Kallen had never cared much for nobles; her concern was always with the ordinary folk.

Pfft—

Setsuna nearly laughed aloud as he gently patted her head.

”Well said. You’re already a model citizen of the Starsea Empire.”

”Ngh...”

”They’re in such a rush to find me because they want to use my power—and that of the Divine Key—to make me serve Schicksal again, aren’t they?” Kallen said angrily.

”That’s... not inaccurate,” Setsuna replied, still smiling. He motioned for her to calm down.

At this rate, if Schicksal actually did manage to find Kallen, her first words would probably be, ’Can you all just surrender to the Commander already?’

It’d probably drive them insane.

Anyone who had lived under the influence of the Starsea Empire—after experiencing its advanced civilization—could no longer think or act like the feudal natives below.

Their perspectives, their values... were worlds apart.

”But we’ll wait a little longer and see how things unfold.”

”After all, many people haven’t appeared yet. I’m curious to see what becomes of them.”

Setsuna waved his hand.

Shhh—

Spacetime began to flow once more as the transdimensional starship advanced along the timeline.

Five years... twenty... fifty... one hundred...

Everything below flashed by in fast-forward.

He watched as both Schicksal and the Ming Empire worked tirelessly to construct what they called ”warships capable of rivaling the Starsea Empire.”

Countless strange inventions emerged one after another.

Without external interference, they wandered down many wrong paths.

The wheel of history rolled on relentlessly.

Soon, Schicksal fell into internal conflict. Under Otto’s schemes and manipulations, he—just as in the original timeline—inevitably rose to become the ruler of Schicksal.

With his newfound power, he accelerated research into the Starsea Empire and advanced the organization’s space exploration agenda.

Realizing that conventional technology would never suffice to reach their goal, he turned his attention elsewhere—toward Honkai energy.

Within the Void Archives, Otto discovered a vast repository of technologies left behind from the Previous Era.

Schicksal’s technological level soon surpassed the rest of the world.

Otto even began to entertain thoughts of once again conquering the world through superior technology.

But technology far beyond its era inevitably led to Honkai outbreaks—and combating the Honkai remained Schicksal’s top priority.

”...”

Setsuna gazed down at the world below as centuries passed in a blur.

Human civilization rose and fell, stumbling forward into the modern age.

With the Science Division’s subtle interference, several crises caused by Honkai energy experiments were quietly resolved.

”Whoa...”

The crew aboard the starship looked dazed.

In just a few days, they had witnessed humanity’s progress across hundreds of years—fast-forwarded from the Renaissance to the modern era.

[Temporal Coordinates Confirmed — Year 1951]

As the ship’s AI announced in its calm mechanical tone, everyone realized with a start that more than five centuries had elapsed.

”Unbelievable... truly unbelievable...”

Fu Hua, Cang Xuan, and Dan Zhu all murmured in awe.

To casually cross centuries of history—it was a dreamlike experience.

On Mount Taixuan, every trace of the School of Taixuan had vanished over a hundred years ago.

Below, cities had risen, cars filled the streets, and airplanes wove dense paths across the sky.

Humanity stood at the very threshold of the Space Age.

Driven by their obsession with reaching the stars, Schicksal’s accumulated technology far outstripped both the original timeline and contemporary Earth’s level.

They had skipped over the stage of developing chemical-fueled rockets and were directly researching Honkai energy-powered starships.

It was only a matter of time before the first spacecraft took flight.

However, despite their astronomical advances and the ability to chart the solar system with telescopes, they still found no trace of the Starsea Empire.

From high-dimensional space, the transdimensional ship observed the world silently. Honkai Station-1 remained perfectly hidden under optical camouflage and signal suppression, utterly invisible to the natives unless approached at extremely close range.

”We’re stopping at this point in time for a reason, right?” Dan Zhu asked.

”Mhm. According to our simulations, this is a key temporal node,” Kayo Senju nodded.

”Now that we’ve entered the current civilization, we won’t be jumping decades or centuries ahead anymore. Every certain interval, we have tasks to perform.”

”At specific points in history, we’ll intervene—collecting individuals and recovering essential artifacts.”

As she spoke—

Shhh—

A massive holographic tree diagram appeared before them.

On the 1951 timeline, countless events were mapped out.

Among them: the First Honkai Eruption, the subsequent schism within Schicksal, and the founding of Anti-Entropy.

Compared to the original storyline, the timeline had shifted slightly forward—but overall, the corrected trajectory remained mostly consistent.

”At this point, we’ll need to retrieve the Core of Reason—the first Herrscher’s core. Hmm... might as well bring those scientists along too.”

”They’d fit perfectly in the Science Division.”

Grey swiped across the holographic display, highlighting several profiles.

Edison, Tesla, Einstein, Planck... and so on.

All names legendary in Earth’s history—but in the Honkai universe, every single one of them was a woman.

”...Seriously? You guys used to joke about King Arthur, Nero, and Mordred being girls—but this world’s no better!” Gudako complained, glaring at Fu Hua and Kallen.

”...None of you have any right to talk,” Setsuna interjected quickly, stopping both sides before the argument spiraled further.

He finalized the plan for their operation in the modern era.

By traveling through time and appearing at critical moments, they would intervene in major events, retrieve valuable relics—and, of course, the girls involved.

In the end, they would conquer the entire world.

”Fu Hua, take the Angeloids with you. This mission’s yours.”

Setsuna piloted the starship as its dimensions contracted. The view outside the porthole twisted into a kaleidoscope of light before the hull trembled softly.

BOOM—

The vessel descended from higher-dimensional space into the Honkai world of 1951.

”I wanna go too! Let me see what the Herrscher of this era looks like!” Senti shouted, raising her hand.

”Alright,” Fu Hua replied calmly.

”It won’t take long—half a day at most.”

”Wouldn’t retrieving the first Herrscher Core and those scientists drastically alter future history?” Cang Xuan asked, leaning forward from her yin-yang sphere.

”Don’t worry—it’s all part of the plan!” Grey declared, thumping her chest confidently.

”I told you, everything in this world’s future—every single event—is within our calculations.”

”...”

”Oh? Then tell me, what happens later?” Setsuna asked curiously.

”I can’t go into the math behind it, but I can give you the conclusion,” Grey, clearing her throat as she looked toward the massive data screen filled with cascading light.

”Theresa will become your grandmother. Kiana will grow up to be humanity’s greatest astronaut.”

”The butterfly effect is amazing, isn’t it?”

”???”

”WHAT?!”

—

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