Crossover Shipgirls: Building a Dimensional Empire from Scratch

The group stayed in the Demon Slayer world for a few short days.

Setsuna made a round of inspections across various countries and regions.

Thanks to the strong intervention of the Bulins and Angeloids, Earth here had developed quite evenly.

Whether it was an African tribe or a developed European nation, development had been brought up to nearly the same level.

After all, everyone was a vassal state now—working diligently, with no one considered nobler than another.

The shipgirls managed the place so well that there was hardly anything to criticize.

Compared to the chaotic mess this world used to be, it was now a hundred times more prosperous.

”Ah, I don’t even recognize the way home anymore.”

Walking down the street, the Butterfly Sisters couldn’t help but sigh with admiration.

It had been almost three years since they last returned.

The buildings lining the streets had shifted from Taisho-era style to a modern look.

The once-familiar scenery had completely changed.

To facilitate management, the Bulins had demolished and rebuilt the entire city. Skyscrapers now towered above the urban landscape, nothing like how it was in the 20th century.

Such was the power of an advanced spacefaring civilization.

”To be honest, I was a bit scared when the Commander first started conquering the world.”

Shinobu looked up at Setsuna.

”Back then, newspapers were saying some evil alien had violently taken over several nations, even staged another Black Ships incident, and forced the shogunate into vassalage.”

”I thought the Commander would treat us as slaves, sending us to dig in caves or something...”

”A lot of people even said they’d rather die than submit, and formed guerrilla units to hide in the mountains.”

Pfft—

Setsuna chuckled as Shinobu reminisced.

During his first visit to the Demon Slayer world, after dealing with Muzan, he had swiftly conquered the world with overwhelming force. Naturally, that would have triggered fierce backlash.

But back then, it was the fastest and most thorough way. Only by establishing dominance could he get the other world leaders in line and ensure smoother management later.

”And then?”

He patted Shinobu on the head.

”And then...”

She thought for a moment.

”The Bulins brought over tons of advanced stuff. They built hospitals, railroads, and distributed food and medicine to the poor.”

”Then people started thanking the Commander for his grace, calling you a savior. Well, except for the shogunate—they weren’t too happy. But ordinary folks were pretty pleased.”

”One day, Kanae said she wanted to thank the Commander in person, so we boarded Ning Hai’s ship and headed to the capital.”

”That was the start of our ’I-Get-It-Now’ moment.”

Setsuna and Gudako burst out laughing.

When you put penicillin, bread, and electricity in front of the common folk and told them it came from the suzerain state—

Who do you think they would support? The suzerain, or their decaying old shogunate?

The group wandered casually through the streets.

While traveling, everyone wore matching uniforms.

When passersby saw the Starsea Empire emblem on their clothing, they automatically stepped aside, standing respectfully on either side of the road with bowed heads and hats removed.

Only after Setsuna’s group had passed did they dare to glance back at them from afar.

They didn’t even need Angeloids to clear the way. The crowd was orderly on its own, and no one dared approach for small talk.

—After years of careful management and shaping public opinion through both actions and words, the Starsea Empire had established an unshakable sense of awe in people’s hearts.

It wasn’t just about raising living standards and technological advancement, but instilling proper reverence toward their suzerain.

Balancing grace and authority was the best way to govern a vassal world.

”Even the shogun’s outings weren’t like this... Feels like we’re emperors or something?”

The Butterfly Sisters still weren’t used to this shift in status.

At the base, they were just ordinary human girls. But upon returning to their homeland, they had suddenly become the elite.

Even former high-ranking officials who had never met the Demon Slayer Corps now had to bow to Kanae.

”So impressive...”

Kanao and Shinobu looked at Setsuna again, their eyes filled with near-fanatical reverence.

It was all because of the Commander.

That man who held supreme power.

Just by being his companions, they had received a tiny bit of privilege—and that alone elevated their status to the highest level here.

No one could match his stature. Compared to him, every other man they’d seen was no more than an insect.

”I want to marry the Commander, just like big sister did.”

Shinobu mumbled quietly.

”Me too.”

Kanao nodded.

”...”

”The Commander’s charm really is something else...”

Chen Hai, walking beside Setsuna, overheard the girls and commented with a half-smile.

”Well, I can’t really judge them. The sisters back at the port are all itching to make a move too.”

”Hmm? What are you all talking about?”

Gudako was currently basking in the sense of superiority granted by her suzerain status and enjoying it to the fullest.

When she stood in front of a shop, the owner, seeing the emblem on her clothes, first froze, then immediately cleared out the shop, grabbed a bag, and began following her. Whatever she pointed at, he packed.

Not only did he not ask for a single coin, but even asked if it was enough, offering more next time if needed.

This zero-cost shopping spree delighted the embodiment of human evil.

The gloom from being ditched by the Commander due to her recent stupidity vanished in an instant.

”???”

”Wait, do you really like local trinkets and snacks that much?”

Setsuna looked puzzled at the bag Gudako carried.

It was full of things like sculptures, snow globes, and snacks like jelly, candy, and cookies.

All of which were clearly inferior to what the Bulins made by several grades.

”Commander, you don’t understand. Free stuff tastes better.”

”This is tribute from a vassal state.”

Gudako stuffed a jelly into her mouth and handed out candies to the Butterfly Sisters and the shipgirls.

Seeing a clothing store up ahead, she was ready for another raid.

”Anyone want to come with me?”

Setsuna flicked her on the forehead.

Things in the capital were free to eat and use, but she was clearly just doing this for fun, reveling in the perks of her position.

That’s not how tributes were supposed to work.

Wandering around with a bag, looting the streets, was beneath the suzerain’s dignity.

Eventually, at the suggestion of the Demon Slayer girls, they arrived at a familiar location.

The Swordsmith Village.

Nestled in the mountains, it was originally the logistics hub of the Demon Slayer Corps. Outsiders couldn’t reach it without a complicated transfer process. Most people couldn’t even find the road.

Now, the surrounding area had been fully developed.

A wide road led directly from the foot of the mountain to the destination, with mines and quarries visible along the way.

The clanging of metal rang out continuously.

”The Nichirin Blades were forged here, Commander.”

”The one I gave you came from here too.”

Kanae said, clinging to Setsuna’s arm.

”Mm.”

That blade represented the girl’s small affection. Setsuna didn’t need it, but he had always kept it stored in his inventory.

After entering the village,

it was noticeably more modern.

Electricity, multi-story buildings, even a small airport had been built.

With no demons left in the Demon Slayer world, the Nichirin Blades had become more of a cultural artifact.

Occasionally, shipgirls or other tourists would buy a few for collection.

”Kanae!”

Familiar faces from the Swordsmith Village rushed over upon seeing the Butterfly Sisters.

But upon noticing their uniforms, Setsuna, and the shipgirls, they respectfully stepped back, bowing their heads.

The time apart hadn’t been long, but their statuses had changed drastically.

”It’s alright, we just came to visit.”

Kanae looked at the overly nervous swordsmiths, unsure whether to laugh or cry.

She was now the highest-ranked among all the Demon Slayer natives.

Even higher than Nezuko or Kanao—because she was the Commander’s wife.

It truly felt like an imperial consort returning home in glory.

”Kanae, is he your husband?”

An elderly woman shuffled forward and asked quietly.

Setsuna recognized her as Haganezuka, one of the swordsmiths.

”Yes.”

Kanae blushed slightly, nodding with a mix of pride and shyness.

”I see. Only a man like that could be worthy of you.”

Haganezuka patted her shoulder and snuck a few glances at Setsuna.

So imposing, clearly on a different level than anyone here.

No wonder such a talented, kind, and beautiful Flower Pillar fell for him.

”It should be my honor to be by the Commander’s side.”

Kanae gently corrected her.

After a brief chat—

”Ah?”

Haganezuka and the others nearly collapsed when they learned Setsuna was actually the leader of the suzerain state.

They hurriedly bowed and apologized, nearly kowtowing.

Setsuna waved it off and casually asked a few questions about how things were going, signaling for them to carry on as usual.

The Butterfly Sisters exchanged a few more words with the villagers, then waved goodbye.

...

”Commander, to think this uniform has such an effect now...”

Walking down the road, Nagato quietly tugged on Setsuna’s sleeve.

In just half a day, she had come to fully appreciate the power of this outfit.

In a vassal state, wearing it was the same as announcing one’s connection to the suzerain—a symbol of status.

Everyone showed respect.

”I used to think it was too stuffy, the color scheme too severe...”

”Was this part of your plan too, Commander?”

”Mm.”

Setsuna chuckled.

When the civilization was first established, the uniform had two purposes: improve recognition and give the shipgirls new outfits.

Some shipgirls’ casual wear back at the port was veering into R18 territory—they couldn’t exactly go into battle wearing revealing outfits that showed too much skin.

But looking at it now, the uniform had ended up serving a broader, unintended purpose.

”As expected of the Commander, truly farsighted...”

”We should learn from your example...”

A few shipgirls quietly began mentally overthinking things.

--------------------------------------------------------------------------------------------------------------

40 Advanced Chapters Available on Patreon:

Patreon.com/DaoOfHeaven