Crossover Shipgirls: Building a Dimensional Empire from Scratch

After the routine welcome banquet ended.

The group from the Honkai world mingled and got acquainted with the Heroic Spirits, Spirits, and shipgirls of the capital.

Setsuna spent some time arranging their placements.

Yae Sakura, Yae Rin, and the other younger ones were all sent to school to study. Cangxuan, Dan Zhu, and Little Fuxi naturally joined the Research Division.

Senti, Fu Hua, Kallen, and others were not given tasks for the moment.

Every day, they were accompanied by shipgirls or Angeloids, traveling across Earth to visit the many miraculous creations of interstellar civilization.

”Mm…”

At the top of the administrative center—

”Commander, this is the report on base development during your expedition.”

Yat Sen transmitted a report to Setsuna.

When the Commander was away exploring other worlds, Yat Sen or Richelieu usually oversaw administration.

Unless an emergency occurred, reports were compiled and presented once he returned.

”Alright.”

Setsuna opened the holographic display.

The shipgirls, diligent and meticulous, had summarized all base information.

It covered territorial expansion, planetary development, production figures, and management of vassal universes.

”Any unexpected incidents?”

”None. Thanks to the Sophons, managing vassal worlds has become far easier. The shipgirls have been freed up considerably.”

Yat Sen smiled as she answered.

”From a management perspective, the Sophons are much more efficient than we are. Everyone feels much lighter now.”

”Good.”

Setsuna skimmed through the report.

Most of it was within expectations.

The Angeloids and Bulins were rapidly developing their universe, with the farthest colonization teams reaching over a hundred light-years away.

The shape of an interstellar empire was forming.

At the same time, starbases were pooling resources to boost population.

The current bottleneck for the Starsea Empire wasn’t resources, but manpower.

With more than a dozen vassal universes, resources were effectively limitless—

As long as they could be developed.

Even with Bulins and Angeloids working day and night in the stellar shipyards to manufacture Wisdom Cubes and ship hulls, producing new Bulins and Angeloids, it was still a drop in the bucket for so many universes.

”Tsk, just fully developing the Milky Way alone would take who knows how many Bulins. And we’re opening up over a dozen universes at the same time… the manpower shortage is real.”

Setsuna sighed.

He had once thought a population nearing a hundred million was vast, but spread across so many universes, it was pitifully small.

Even though humans of the vassal universes could handle mining and farming in their own realms, their efficiency was still far below that of Bulins and Angeloids.

”Our backyard is too big—we can’t even finish touring it all~”

Richelieu chuckled.

”We’ll take it slow. Once the Bulin population grows, their efficiency will rise too.”

”Didn’t the Sophons say our population should surpass ten billion within five years? By then, developing several thousand light-years around us shouldn’t be an issue.”

”True.”

Setsuna mulled it over. The population problem would just have to wait for the Bulins to build it up.

Next, he reviewed other reports.

Another batch of little girls had graduated from school and joined the Research Division in the starbases, studying the strange technologies of various worlds.

For instance, the Life Sciences Department was working on genetic modification to reduce the intelligence of Trisolarans, turning them into mindless laborers suited only for mining and farming.

The Siren shipgirls continued developing controllable dimensional strike weapons in the Trisolaran world. Some civilizations loudly condemned their use of stars for experiments, issuing diplomatic protests against the Starsea Empire.

In response, Purifier conducted an experimental dimensional reduction strike on the protester’s homeworld—downgrading the entire star system by one dimension.

She regretfully declared the experiment a failure, while expressing deep condolences for the destroyed civilization.

”...”

Setsuna saw no issue. In fact, it was fine.

He then checked on his companions.

The Butterfly sisters from the Demon Slayer world, Nezuko, as well as Akame, Kurome, and the elf archer, were all diligently undergoing their routine training.

Regular training runs in the Goblin Slayer world, study sessions in the library, even learning bits of magic from Lucoa…

”Tsk…”

”Leaving things this loosely managed isn’t going to work…”

Setsuna propped his chin, lost in thought.

Shipgirls, Spirits, and Heroic Spirits all had their own systems of power—they just needed gear upgrades or steady training.

But the ordinary human girls were in a somewhat awkward position.

They couldn’t wield Noble Phantasms like Heroic Spirits, nor could they use the powers of shipgirls, dragon maidens, or Spirits.

All they could do was patch together various skills, arming themselves with Teigu, magic scrolls, and other equipment.

”Hm?”

Lifting his head, he spotted Fu Hua studying some documents.

”There we go.”

Setsuna stepped forward and patted the immortal’s shoulder.

”I have a task for you—rebuild the School of Taixuan here. Take in some disciples.”

”Eh?”

For a moment, Fu Hua didn’t react.

”I have many talented young girls who need your guidance.”

Setsuna quickly explained.

In terms of potential, Kanae, Kanao, and Akame had all undergone genetic modification. Though still inferior to Fu Hua as a MANTIS, they far surpassed the Six Disciples of Taixuan.

And since most of them were swordswomen, the Edge of Taixuan would suit them perfectly.

Far more than the Butterfly sisters’ old breathing styles or the crude sword arts of Night Raid.

”Well, since you put it that way, I can give it a try.”

Fu Hua paused briefly, then nodded.

”Teaching… I’ll do my best, mm.”

...

A few days later—

In a corner of the capital, the Bulins had constructed a traditional complex modeled after Mount Taixuan.

They even recreated the sky-reaching peak.

In the courtyard, Fu Hua stood in flowing robes, Xuanyuan Sword in hand, gazing at the rows of girls before her.

Demon Slayer Corps members, Night Raid fighters, adventurer girls from the Goblin Slayer world, the Sword Maiden, and more—all gathered here.

”Mm. Your physical qualities are impressive, even stronger than Lin Zhaoyu.”

”But your weapons and techniques are too scattered.”

After having them demonstrate a few moves, Fu Hua judged that any one of them would be considered a rare martial prodigy in the Saga of the Shattered Swords world.

And their youth made them perfect for tempering their sword-hearts in the Edge of Taixuan.

”Very well. From now on, I’ll pass on martial arts to you. With your talents, mastering the Blade Mantra shouldn’t be difficult.”

”And once MANTIS technology is fully analyzed, your power will rise even further.”

”W-we’ll do our best!”

The girls encouraged one another.

Having finally found a true teacher, they treasured the chance.

They had heard from the Commander that the Taixuan Eminence, if mastered to its peak, could rival even a Herrscher.

The immortal paced before them, gesturing for them to sit.

”The Edge of Taixuan contains five essences—heart, form, will, soul, and spirit. We will begin with the heart.”

As she had once done for Setsuna, she recited a strange mantra.

”This is the Blade Mantra. Remember it, recite it always, use it to temper your hearts.”

”Mm…”

Thanks to genetic modification, their memory was phenomenal. They quickly memorized the complex syllables.

Soon, they began training in the essence of form.

At Setsuna’s request, Fu Hua taught with diligence and care.

She demonstrated the twenty-one forms of the Edge of Taixuan, one by one.

Kanae and the others trained with extraordinary dedication, no less than the disciples she once had at Mount Taixuan.

They practiced from dawn until long after moonrise, stopping only when their bodies could no longer endure.

...

Late at night.

After the group dispersed, Fu Hua lingered a moment, then noticed light still burning in Setsuna’s room at the administrative center.

She tidied herself a little, then walked quickly toward it.

”Tsk, you really dumped a tough job on me. You’d better keep me company…”

The immortal quickened her pace.

But just as she reached the door—

She heard familiar voices inside.

”Commander, we practiced Edge of Taixuan all day today…”

”Mm, we’re still learning the Opening Form. I just picked up the Sea-Cleaving Slash, while Shinobu already mastered the Sky-Splitting Cut.”

”So exhausting… praise us, please…”

”We just want to get stronger, so we can be useful on expeditions…”

”???”

Pushing open the door, she found the Butterfly sisters snuggled into Setsuna’s arms, with Kanae nestled between them.

Seeing Fu Hua, they froze in shock.

”Master? Eh?!”

The sisters were stunned.

Never did they expect to meet their teacher here of all places.

”Am I intruding? I’ll go.”

Fu Hua’s face flushed as she turned to leave.

”No—you came at just the right time.”

Setsuna stopped her without hesitation.

”Come, come. By day you teach Kanae swordsmanship—by night, let them teach you something else.”

”Now that’s what good disciples are for.”

”???”

...

Three weeks slipped by since Setsuna’s return from the Honkai world expedition.

After implementing Sophon technology, most of the workload was handed over to artificial intelligence.

Even with an interstellar empire spanning hundreds of light-years, the burden on its ruler was not overwhelming.

He only needed to handle major decisions and periodically review the progress of vassal universes.

The rest of his time was spent with the girls stationed at the base.

And using his Herrscher powers to help the Life Sciences Department create new Honkai Beasts.

Every so often, a batch of Danger Beasts from the Akame ga Kill world or monsters from the Goblin Slayer world would be brought in.

After being corrupted, they were transformed into various Honkai Beasts, then used for DNA extraction and research.

MANTIS technology was something Setsuna had high hopes for.

And those training under Fu Hua in the Taixuan Eminence were also looking forward to it.

For ordinary humans, this was by far the simplest and fastest way to raise their power ceiling.

One day—

Setsuna was enjoying the soft comfort of Illustrious’ embrace in the harbor area while teasing the little shipgirls, when suddenly news arrived from the Life Sciences Department.

”Commander, we’ve mastered the advanced version of the MANTIS technology. We’re ready for Phase One experiments.”

A few hours later—

Setsuna brought along the Butterfly sisters, Akame, Kurome, and other ordinary girls—plus Gudako, who tagged along out of curiosity—and boarded a shuttle bound for the Lunar Research Center.

By now, the empire’s Research Division had expanded to cover the entire surface of the moon.

Colossal experimental machinery stretched across the skies, Angeloids and uniformed research lolis hurrying back and forth.

From high above, one could see the massive Honkai Beast breeding grounds.

The towering Judgment-level Chiyou, along with various Emperor-class Honkai Beasts that had been manufactured, were all kept like livestock in enormous enclosures.

Scattered among them were hundreds of lesser Honkai Beasts wandering idly about.

From time to time, Angeloids would approach with equipment, extracting samples for comparison and analysis.

”This is… surreal.”

Fu Hua couldn’t help but sigh.

Any one of these Honkai Beasts would cause a bloodbath if released on Earth in the Honkai world.

Even setting aside the feudal natives of the Saga of the Shattered Swords world, Emperor-class Honkai Beasts were not easy prey for human civilization during the old space age.

Clack—

After their shuttle landed, Kayo Senju and Cangxuan, along with Dan Zhu, came out to greet Setsuna’s group.

The two scientists from the Previous Era had quickly adjusted after some time here, fully immersing themselves in the Research Division’s work.

Naturally, they specialized in Honkai energy research.

The group proceeded forward, arriving at a large biological laboratory.

Inside the spacious hall stood two rows of about thirty stasis pods.

Each pod was linked to life-monitoring devices, while holographic screens scrolled with complex streams of data.

”Commander, we’ve made several improvements to the MANTIS technology left behind by the Previous Era.”

Kayo Senju tapped at the holographic interface, bringing up a complicated display as she explained.

”Building on Dr. Mei’s research, and using advanced genetic techniques, we’ve resolved many of the flaws in the original MANTIS system.”

”It’s now safe and controllable—just like the genetic modifications we’ve already performed.”

”Safe and controllable? You mean…?”

Fu Hua blinked in surprise.

”It means it won’t cause irreversible damage to the human body, nor will you need to awaken latent factors in a life-or-death crisis.”

”Immortal, our technology is far more advanced than the Previous Era’s.”

The little loli nodded confidently.

The Previous Era, in order to fight the Herrschers, had attempted to merge human DNA with that of Honkai Beasts to create MANTIS.

Undeniably, the plan produced powerful special operatives.

But it was not without risks. In fact, the Previous Era had mainly produced MANTIS through two methods:

The first method: Meta-Morph surgery, directly modifying the human body. Its success rate was not 100%, and it could cause irreversible damage—Kevin being a prime example.

The second method: to mass-produce MANTIS quickly, Dr. Mei developed the ”Meta-Morph” super adaptation serum.

Injecting the serum into test subjects allowed them, under life-or-death pressure, to awaken hidden potential and activate the ICHOR factor, becoming MANTIS .

Fu Hua herself had become a MANTIS through this second method—awakening her factor in sheer desperation while facing a one-sided slaughter by an Emperor-class Honkai Beast.

As the little loli explained, she pressed a button.

Click—

Two rows of stasis pods hissed open.

”With the serum now, all you need to do is inject it, sleep a few days in the pod, and that’s it. No side effects, no risk to your life.”

”In AI simulations, the success rate is virtually 100%. At worst, if DNA compatibility fails, we just give another injection or a small surgery.”

”Interstellar age technology—amazing, isn’t it?”

”…”

Fu Hua was impressed.

Thinking about it, optimizing away the flaws of Previous Era MANTIS tech made sense for an FTL civilization.

Blue surpasses indigo—they had taken Dr. Mei’s legacy and pushed it further.

”So what Honkai Beasts can we fuse with? Weren’t you working on a Chimera Project to combine all their DNA?”

Gudako asked eagerly.

”For now… step by step. In the first round, you’ll all fuse with Emperor-class Honkai Beasts to let your bodies adapt to Honkai energy.”

”Once you’re proficient, then we’ll move on to higher-level modifications.”

”After all, for us, letting one person fuse with multiple Honkai Beasts’ DNA isn’t difficult.”

Kayo Senju answered calmly.

”Ohh…”

The group thought for a moment, then nodded in understanding.

Honkai energy was new to them—trying to take it all at once wasn’t realistic.

Start with Emperor-class fusions.

Once they mastered control, they could gradually move up.

The Butterfly sisters, Akame, Kurome, along with Kallen, Yae Sakura, and Yae Rin all lay down inside the pods.

Cangxuan and Dan Zhu worked at the consoles, then turned to the girls:

”What direction of enhancement do you want?”

”There are Honkai Beasts specializing in water, thunder, fire, or ice elements, others that boost strength or agility. Choose what you want on the interface.”

”Whichever you pick, we can make it compatible.”

Shua—

Before each of them appeared a selection interface.

Clicking a Honkai Beast’s name displayed the DNA’s power boost.

”...”

”Uhh… so hard to choose. Elemental magic sounds great, but strength enhancements are tempting too…”

”And this one increases reaction time and memory? Basically makes you smarter? Hm…”

”Which one…”

The Butterfly sisters mulled it over for ages before deciding.

Gudako, on the other hand, didn’t hesitate at all:

”Same as always—max out strength and regeneration. Intelligence is useless.”

”Thinking is the Commander’s job. I’ll just be a happy orc.”

”…Fine.”

Setsuna almost laughed out loud at her.

”By the way, Immortal, you can undergo modification too.”

Seeing Fu Hua standing aside, Kayo Senju reminded her.

”Since you already fused with an Emperor-class Honkai Beast, your adaptability to Honkai energy is very high.”

”This time, we can try giving you a Judgment-level Honkai Beast—Chiyou.”

”Huh?”

The immortal was stunned, as though she’d just heard a myth.

A second round of modification—merging multiple Honkai Beasts into one body.

”…Is that possible?”

She looked to Setsuna hesitantly.

”Don’t worry. It’s absolutely safe. If anything happened to you, the Commander would hang us out to dry!”

Cangxuan clicked her tongue.

”Go for it, go for it. Who knows, it might even make you bigger.”

Senti whispered devilishly in Fu Hua’s ear.

”Think about it—you’ve been stuck at age 17 because of Garuda, unable to grow.”

”Maybe fusing Chiyou, a Judgment-level Honkai Beast, could fix your pitiful figure. That thing’s massive, after all.”

”???”

The immortal froze, then promptly delivered a critical hit to Senti’s head.

Bonk—

”Ow—!!”

The Herrscher of Sentience crouched down, clutching her skull.

”You fossil, what’s wrong with you?! I was trying to help! Don’t want it? Fine, let me try!”

”Of course I’ll try it.”

Fu Hua’s face remained calm as she lay down inside a stasis pod.

—

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