Crossover Shipgirls: Building a Dimensional Empire from Scratch

Griseo and Fu Hua looked at Kevin in his current state, their expressions subtly complicated.

In their memories, the strongest leader of Fire Moth was now just a brash young man.

Now that the Starsea Empire had arrived, the responsibility of ”saving the world” would no longer have anything to do with him.

From this moment on, the timeline of history had changed.

”In that case... perhaps this isn’t so bad?”

Fu Hua closed her eyes and thought for a moment.

To live out one’s life as an ordinary person on Earth, peacefully and without turbulence—

For people of the Previous Era, that had already been a luxury.

”Ah... then what about the others?”

Griseo froze for a second.

If even Kevin was like this, then the rest of Fire Moth’s companions went without saying.

In their current state, they were certainly nothing like the older brothers and sisters in her memories.

”You might have to become their senior from now on.”

Setsuna pinched Griseo’s cheek.

”Eh—eh—eh?”

Griseo suddenly realized that she had only just grown up, and already she would have to face something incredible.

...

Below, the squad led by Grey immediately began search operations based on Sophon’s guidance.

”Let’s retrieve the closest one first... let me see...”

”Dr. Mei—oh, wait, she’s not a doctor yet, is she?”

The students and teachers at the academy had long since been evacuated.

All the way at the deepest part of the laboratory,

A girl with a black ponytail and a white lab coat was flipping through something amid a mountain of books.

Quantum mechanics, astrophysics...

For ordinary students at Chiba Academy, such material was severely beyond the syllabus. Even teachers would struggle to master it all.

Yet Mei was completely immersed in it.

All the noise of the outside world had nothing to do with her. She had no interest in anything beyond study. Her life goal was to become a scientist.

Classmates inviting her to watch movies or play games—she did not care.

The unrest within Chiba Academy—she did not care.

Even if aliens arrived, they could not interrupt her reading.

”...”

”Hm?”

Hearing footsteps, Mei looked up and saw a gray-haired nanorobot standing before her.

”The restroom is over there.”

She pointed in a direction and lowered her head to continue reading.

”???”

Grey nearly laughed in exasperation.

”Miss Mei, this is the Starsea Empire. We invite you to join the Empire’s Research Division. Your talents will be better utilized there.”

”...”

”What? Where? What kind of research?”

Mei did not even question the other party’s origins. Her focus was entirely elsewhere.

”Honkai energy, life sciences, physics... take your pick.”

Grey projected countless complex and profound formulas before her—

Mysteries humanity had yet to solve, theories that existed only in conjecture.

”Here is the proof of the Goldbach’s Conjecture and the Riemann Hypothesis.”

”Here is a supplementary theory to general relativity under faster-than-light and hyperdimensional conditions... oh wait, Einstein won’t be born for another fifty thousand years. Do you even have relativity yet?”

”Here is the theory of imaginary singularities...”

”Ah!!”

Mei was instantly captivated. She felt as though she had touched the very truth of the world.

Her eyes did not blink.

The more she read, the more absorbed she became, jotting down notes from time to time.

”My God... so that’s how it is... how could you possibly...”

The girl let out soft exclamations as she read.

After only a few pages—

Swish—

Grey retracted the holographic interface.

”Ah???”

”Hey!! Wait a second!!!”

Mei glared at the nanorobot for such shameless cliff-hanging behavior.

For a scientist, having the most brilliant part of a proof cut off midway was pure torture. It was like ants crawling all over her body.

”Want to keep reading? Come with me.”

Grey snapped her fingers.

Clack—

A small shuttle docked outside the window.

”...”

”Fine. Make it quick.”

Without hesitation, Mei hastily packed her equipment and boarded the ship.

”... Bookworms really are easy to trick...”

...

Elsewhere.

Elysia and Mobius’ confusion did not last long.

Vmmmm—

A few minutes later.

The communications and electronic devices within Fire Moth’s base were completely cut off under powerful electromagnetic interference.

A slightly smaller vessel landed near their laboratory.

Griseo lightly jumped down from the ship and greeted the two of them.

”Sister Elysia! Aunt Mobius!!”

After who knew how many eras, Elysia looked exactly the same as in her memory.

No matter how much time passed, she remained just as beautiful.

Her slightly wavy pink hair fell neatly, her smooth side bangs framing her face, tied into a ponytail at the back.

She wore a white top with black sleeves and a black shawl, adorned with many purple accents that perfectly accentuated her figure.

Mobius appeared somewhat younger than in Griseo’s memories, dressed in the white lab coat typical of a scientist.

”Eh?”

Both of them were startled, staring at the grown-up Griseo in confusion.

”Being called ’big sister’ by a cute girl makes me very happy, but little one, could you first tell me who you are and why you’re here?”

Sitting in her chair with one leg crossed over the other, Elysia sized Griseo up, amusement and curiosity dancing in her eyes.

She could tell this girl was no ordinary human—and she knew their names. Very strange.

”Wait. Why is she ’big sister’ and I’m ’aunt’?!”

Mobius’ lips twitched. Something about that felt very wrong.

”Umm... I’m just used to calling you that...”

Only then did Griseo realize that, at this point in time,

Elysia and Mobius did not know her yet.

—Even if they did, they had never seen her grown-up form.

”My... my name is Griseo. I’m from the Starsea Empire.”

Introducing herself to her former companions felt strangely surreal.

”We’re here to solve the Honkai problem of this era. Um... the Commander wants to meet you. Sister Elysia, Aunt Mobius, could you come with me?”

”Say it again—I am not an aunt!!!”

Mobius pounded the desk several times in strong protest.

”You’re aliens?”

She asked again.

”Uh... yes, but not entirely...”

Griseo did not quite know how to explain. The Starsea Empire was indeed from another world, yet she herself originally belonged to this one.

”Oh?—”

Elysia tilted her head, thoughtfully considering Griseo’s words.

”You’ve really said quite a number of astonishing things, haven’t you...”

She beckoned to Griseo. For some reason, she felt as though there was a certain affinity between them.

Even though they had never met, there seemed to be a faint connection in the unseen.

”So cute! Mmm... you must have been even cuter when you were little!”

Elysia pinched Griseo’s cheek, steering the conversation in a very strange direction.

”...Eh?”

Griseo wanted to say that she had only grown up not long ago.

”Hm?”

Elysia suddenly paused, leaning closer to Griseo.

”Honkai energy? You... you’re not an ordinary human, are you?”

She sensed powerful Honkai energy emanating from Griseo, along with strength far beyond that of a normal human.

In an era where even the MANTIS surgery had yet to be born, this was exceedingly peculiar.

”And you said you came to solve the problems of this era? What do you mean by ’this era’? Could you explain that to me?”

”Umm...”

Griseo realized she was completely incapable of handling Elysia.

”Well... let’s go meet the Commander together!”

...

Half-believing, half-doubting, the two of them followed Griseo and boarded the ship.

”By the way, you’re not worried at all?”

Mobius quietly poked Elysia.

”Oh my, beautiful girls are always good people. What’s there to be afraid of?~”

Elysia hummed an unknown tune, curiously observing everything around her.

Angeloids, anti-gravity spacecraft, a space fleet...

To this era, all of it was far too advanced and novel.

”Amazing. A civilization capable of building something like this must not have been threatened by Honkai, right?”

”Mm... if humanity continued to develop, how long would it take to reach this level?”

”By the way, you’re humans too, aren’t you? Right?...”

It sounded like she was talking to herself, yet also asking questions, tossing out a string of exclamations and inquiries.

The shuttle rose steadily and entered the interior hangar of the starship.

After passing through a long corridor bridge,

At the top bridge of the Eternal Snowfall, she saw a man seated before the main control console, planning something on a holographic interface.

”Ah...”

Beside him, Fu Hua saw Elysia again and felt a surge of complicated emotions. Unfortunately, at this moment, Elysia did not recognize her.

”Hello, Elysia. We spent a great deal of effort and crossed a very long stretch of time just to meet you.”

Setsuna turned around and spoke with a smile.

”Or perhaps I should call you... Miss Herrscher of Origin?”

”Hm?!”

Elysia froze.

At this time, within Fire Moth, no one knew her true identity: the earliest Herrscher to be born—the Herrscher of Origin, and the Herrscher of Humanity.

She had been born between heaven and earth, loving humanity and everything about life. As a warrior, she had joined Fire Moth to help humanity fight against Honkai.

This secret was not supposed to be known by anyone else.

”Oh my, what are you talking about? Making baseless accusations about someone’s identity is very rude, you know~”

Elysia attempted to play it off cutely.

”If my other companions misunderstand, it’ll cause me quite a bit of trouble.~”

”...”

Setsuna extended his hand, gathering familiar Honkai energy within his palm, displaying his power to her.

”It’s nothing special. There’s a Herrscher of Sentience here, a Herrscher of the Void back at the base. I’m the Herrscher of Finality.”

”Theoretically speaking, you should be a part of me as well, shouldn’t you?”

”Eh?”

After seeing the tangible Honkai energy condense in Setsuna’s hand.

Elysia’s previously playful attitude and teasing expression immediately faded.

She stared at him for a long while. Her gaze shifted to Senti, who stood not far away watching the show with an indifferent look, then returned to him.

”You’re... Herrschers too?!”

From the power radiating off the two of them, Elysia clearly recognized that they were her own kind.

”Ah?!”

Mobius was horrified.

In the span of five minutes, she had received an overwhelming amount of information.

Elysia was a Herrscher. These aliens were Herrschers as well. Her brain could barely process it.

”I told you already, Elysia. I command the power of Finality.”

”You can also be regarded as a part of me. You know that, don’t you?”

Setsuna gestured for her to step forward, a faint trace of Honkai energy drifting from his palm.

”...”

Elysia closed her eyes, sensing that strange energy.

Deep and unfathomable. She felt an innate affinity with it. Even though she had never met Setsuna before, instinct alone told her who he was.

”This...”

”How could you possibly...”

The pink-haired girl rarely lost her composure, but now she was visibly shaken. After steadying herself and confirming that Setsuna bore no hostility toward them, she stared at him again.

”Wait, that’s not right!”

”Aren’t Herrschers supposed to be beautiful girls? Um... I feel like the Herrscher of Finality should look different?”

Pfft—

Setsuna couldn’t help laughing.

”Who taught you that? Do you want me to summon the Herrscher of Finality of this era? It wouldn’t be that difficult for me.”

”Eh?”

Elysia jumped in fright and hurriedly waved her hands.

”No, no, no!!”

”More importantly... Mr. Herrscher of Finality, I have a few questions for you.”

She leaned forward with both hands on the table, propping up her chin as she studied him with bright curiosity.

”Where are you from? What exactly is your identity? Were you born in this world like me?”

”And most importantly, why have you come to this world?”

As a fellow Herrscher, Elysia understood Setsuna’s strength all too well.

Even without counting the strange powers surrounding him or the entire fleet behind him, the power of Finality alone was something present-day Earth had no means to resist.

Fortunately, this Herrscher of Finality did not appear to have lost his reason like the Herrscher of Reason or the Herrscher of the Void before him. He could be communicated with.

”That... is a long story.”

Setsuna gestured slightly.

Mobius sat down across from him as well, listening intently.

”We come from this world’s future. We are here to resolve the threat of Honkai and to save your fate.”

”...”

Both of them stopped breathing for a brief moment.

They exchanged a glance. Setsuna did not look like he was joking.

”The future? How far in the future? One hundred years? No... judging by your ships, it would take at least five hundred years to build something like that, right?”

Elysia tilted her head with a beautiful smile.

”By then, has humanity completely defeated Honkai? Have we reached space? Flown beyond the solar system? And what about me?”

”Did I become an idol for all humanity? How far did Earth develop?”

Her eyes sparkled with boundless longing for the future.

”You probably got fatter.”

Mobius muttered dryly.

”Hey!!! What do you mean?! My weight has never changed!”

Elysia lightly punched Mobius.

”...”

Setsuna paused.

”It’s fifty thousand years in the future.”

”You fought bitter battles against Honkai and the Herrschers of this era, yet you were still unable to prevent humanity’s destruction.”

”After the Herrscher of Corruption severed civilization, Fire Moth gathered its final strength and fought one last battle against the Herrscher of Finality on the moon. The gap in power was too great.”

”Human civilization was wiped out by the Herrscher of Finality. Only fifty thousand years later did humanity re-evolve from the wilderness, ushering in a new era. To Earth, you became the Previous Era.”

”...”

”Ah...”

Silence.

Elysia and Mobius fell into a long silence.

From Setsuna’s mouth, they had just heard the ultimate judgment of their own fate.

Their unknowable future was merely history to others.

”So we... failed?”

Elysia sighed softly.

She leaned back in her chair, staring blankly at the dome outside the viewport.

Mobius’ expression was even more complicated. She wanted to ask something—about whether humanity had done something wrong, about whether her research direction had been mistaken.

A thousand words gathered in her throat, yet none could be spoken.

Fifty thousand years.

A number so vast it was suffocating.

Humanity, at this moment, was engaged in a struggle destined to fail.

”...Did I at least die like a human in the end? Did I help them?”

Elysia asked softly, posing a strangely phrased question.

”You brought hope to the humanity of the next era.”

Setsuna answered.

”You gave the Herrschers of the Current Era humanity. They possess emotions like you, like humans. Some of them were even willing to stand beside humanity and fight Honkai together.”

”Fire Moth’s efforts were not in vain. Through the flames preserved by the Thirteen Flame-Chasers, humanity advanced its understanding of Honkai...”

”The Project STIGMA, Project ARK, Project VALUKA, and Project EMBER did not achieve their intended outcomes, but humanity’s ultimate victory over Honkai was inseparable from the legacy you left behind.”

He summarized the key points—the four salvation projects, the invasion and analysis of the Will of the Honkai, and so on.

”Oh...”

Elysia listened, utterly absorbed.

Perhaps after learning her final fate, she felt unexpectedly relieved.

It was as if she were listening to a story—her own future recounted by someone else.

”So in the end, through our own sacrifice, we gave the next era’s humanity the power to defeat Honkai?”

”Mm... if you put it that way, it’s not so bad. Humanity won in the end, after all.”

She giggled softly and tucked a strand of hair behind her ear.

”Ah... it’s just a pity I never got to see what human civilization looked like fifty thousand years later. How many interesting things would there have been? How many landscapes I never got to witness?”

A trace of regret surfaced on her face.

It was wonderful to know humanity triumphed over Honkai. Yet not being able to witness that final victory herself felt a little bittersweet.

She looked toward Setsuna and Senti.

”If that’s the case, then technically I’m your senior, aren’t I?”

”Without me, you’d still be Herrschers who only oppose humanity and think about destruction all day, right?”

”!?”

”Is that so? That actually makes a lot of sense!”

Senti almost got led astray by Elysia’s logic.

”She is. I’m not. I come from another world—a larger one.”

Setsuna replied calmly.

”Oh...?”

Elysia leaned in even closer, studying him carefully.

She had suddenly developed a great deal of interest in this visitor from another world.

”So, Mr. Herrscher of Finality, after defeating Honkai in the future, you traveled back to help us former failures?”

”Mm... that sounds rather romantic, doesn’t it?”

She pressed a slender finger to her lips, thinking seriously.

”Our legacy helped humanity fifty thousand years later, and then they turned around and traveled back to help us? Mm, how fascinating~”

To her, this might just be the most interesting thing in the world.

There was nothing more exciting than conversing and fighting alongside travelers from the future.

”You’re not wrong.”

Setsuna smiled.

”So, Miss Elysia, would you like to see the world fifty thousand years from now with me?”

”Of course!”

—

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