Crossover Shipgirls: Building a Dimensional Empire from Scratch

Nightfall.

At the naval base port, a silver-white battleship docked at the berth was brightly lit.

This evening, a grand celebration was underway aboard the ship to commemorate the successful completion of the first expedition. The event also provided an opportunity to sample some of the specialties Ning Hai and Ping Hai had brought back from the Demon Slayer world.

Even many shipgirls from Azur Lane’s base had come over, gathering in Richelieu’s lavishly decorated banquet hall.

This magnificent battleship was perfectly suited for hosting such festivities. Richelieu had adorned her interior in a style both elegant and luxurious.

The silver-white walls, intricate gold embellishments, and French classical decor made the hall feel like a grand chamber in the Palace of Fontainebleau from the 17th century.

Dozens of shipgirls and Bulins mingled in small groups. Destroyers sipped fruit juice, while carriers and battleships mostly held glasses of champagne or red wine.

The table was laden with delicacies from around the globe:

King crab from Alaska, Iberian ham, bluefin tuna, Alba white truffles...

While these weren’t necessarily tribute items from the Demon Slayer world, some had been purchased, while others were gifted voluntarily.

Having an entire world as a resource base had its perks. It ensured the production of strategic resources like coal and steel while offering unexpected luxuries.

”Hey, don’t steal my crab!”

A few small shipgirls squabbled at the table, their cheeks puffed with food.

While shipgirls technically sustained themselves on ship fuel, they didn’t mind indulging in gourmet cuisine to improve their quality of life.

For those who had followed the vanguard fleet to this new Earth, this was the most lavish dinner they’d had yet.

Kanae and her sisters were initially reserved.

But soon, they were surrounded by enthusiastic destroyers and submarine shipgirls.

”Want me to take you fishing? It’s so much fun blowing up sharks in the Mediterranean—they’re dumb and there’s plenty of them.”

”How about diving? We might catch a giant squid or jellyfish!”

”Or I can take you flying! My jetpack should handle one more person, no problem.”

...

The sisters were utterly baffled. These adorable little girls were shockingly wild and dangerous.

”You call him ’Commander’?”

Shinobu suddenly noticed the shipgirls’ peculiar way of addressing Setsuna.

”Yup, you can call him that too.”

Bluegill responded as if it were the most natural thing in the world.

”Calling him ’Mr. Setsuna’ sounds so distant, don’t you think?”

”Hmm, I see…”

The sisters decided to adopt the new title.

...

Meanwhile, in another corner of the banquet hall:

”You’re here, Commander. Please, have a seat. Would you like something to drink?”

Dressed in a white and gold gown, Richelieu gestured for Setsuna to join her.

Clad in an exquisite French-style evening dress, her golden hair draped evenly over her shoulders, Richelieu exuded a relaxed elegance. She swirled the wine in her glass with a languid air, her stunning beauty captivating to the point of distraction.

”I thought you were only interested in work and prayer.”

Setsuna chuckled as he sat beside her.

”Even I need moments of reprieve outside of work and faith. No devout believer can live on faith alone—they also need food and wine.”

She took a delicate sip from her glass.

”Bordeaux, Château Latour, a ten-year-old Cabernet Sauvignon.”

”Ning Hai and Ping Hai seem quite knowledgeable. This isn’t easy to procure.”

”You really are a French aristocrat... I couldn’t tell the difference.”

Setsuna shook his head.

As the flagship of the Iris Libre faction and a cardinal, Richelieu carried an inherent air of authority.

”Commander, the affairs in the Demon Slayer world have likely concluded. Ning Hai and Ping Hai can handle the follow-up.”

”What’s your next move?”

After some light conversation, Richelieu asked suddenly.

”What’s next…”

”Now that we’ve left the noob village, we’re probably going to face some real monsters next.”

As his secretary ship, Richelieu had spent considerable time with him and learned a bit about the other worlds surrounding theirs.

With a swipe, Setsuna pulled up the Hyperdimensional Star Map and pointed to the remaining worlds.

”Type-Moon, Date A Live, Honkai…”

”These worlds feature true magical powers—not the child’s play of Muzan from the Demon Slayer world.”

”Some powerful Spirits, Herrschers, or Servants could destroy entire cities, nations, or even planets with a mere thought. They’re incredibly challenging adversaries.”

”And their power systems differ entirely from ours. They’re practically a separate civilization.”

From the detailed information, Date A Live and Type-Moon worlds were categorized as magical civilizations. Shipgirls had never encountered such forces before.

However, with greater danger came greater opportunity.

Since Setsuna could assimilate different powers from across dimensions, he saw these worlds as chances to expand his civilization’s potential further.

...

Richelieu listened quietly as Setsuna explained the surrounding worlds.

Propping her chin on one hand, she used the other to adjust his collar.

”That does sound dangerous.”

”But no matter where you go, Commander, I’ll ensure victory is always yours.”

”Thank you.”

Setsuna nodded.

As he glanced at the girl’s charming figure, her beauty enhanced by the warm glow of the lights, he blurted out without thinking:

”You look stunning tonight.”

...

Richelieu blinked in surprise, then burst into laughter.

”What’s this, Commander? Are you complimenting me, or is there something more to it?”

”I’m not that easy to win over. Next time, bring roses and wine. Empty words alone won’t cut it.”

She poked his cheek, then tidied her hair and rose to step outside for fresh air.

...

Watching her retreating figure, Setsuna’s expression turned wry.

”Great. I think I’ve just been outplayed by the big sister type.”

...

With the acquisition of immeasurable resources from another world, the development of the settlement surged visibly.

Not only did some shipgirls begin refitting their hulls with advanced energy weaponry, but the once-stalled production of Wisdom Cubes also resumed.

A few days later.

At the port’s dockyard, Setsuna stood beside the shipyard with a few accompanying shipgirls and Akashi, the repair ship.

In the shipyard below lay ten identical, unarmed transport ships about 100 meters in length. These were the hulls of the Universal Bulins.

Akashi opened a small box with utmost care, revealing ten neatly arranged pale-blue Wisdom Cubes.

”Commander, these are the first batch of Wisdom Cubes we’ve manufactured. With them, you can bestow self-awareness on these ships and transform them into shipgirls, meow~.”

”But be careful this time. Don’t swallow the cubes again!”

Setsuna took the box, sensing the immense power contained within the Wisdom Cubes.

These items were a complete black-box technology—even Akashi couldn’t fully understand their internal structure. She could only replicate them using the established manufacturing process.

As for the principles behind the Wisdom Cubes and how they worked with humans or ships, it remained an enigma.

”Can the cubes work on Gundams? Like creating a mech-girl? We’ve got empty ones like Unicorn and Barbatos, right?”

His imagination began to run wild.

”...”

”In theory, it’s possible. But in terms of combat effectiveness, I think mech-girls would be inferior to shipgirls, meow.”

Akashi scratched her ears, pondering.

”Also, Gundams are designed for standard operation. If you wanted mech-girls, you’d need to redesign their internal structures…”

”Alright, let’s try summoning some Bulins first.”

Setsuna raised a Wisdom Cube high above his head, focusing his consciousness on the nearby ships.

In that instant, he felt his mind connect with the cube and channel into the hulls in the distance.

Shing!

The cube in his hand and the ships transformed into a glowing sphere, gradually twisting and reshaping in midair.

A few minutes later.

A petite shipgirl with short white hair and a skirt landed gracefully on the water’s surface.

She held a large wrench about the size of a human, her tail resembling a charging plug.

Opening her eyes and spotting Setsuna, she immediately lunged at him.

”Burin! Commander, I can lift your fleet, Burin!”

Though this was their first meeting, the Bulin was incredibly enthusiastic, clinging to Setsuna and rubbing against him.

Buzz!

Following the same method, Setsuna quickly summoned several more Bulins.

Ten purple Bulins stood neatly in front of him. Aside from the numbers on their badges, they were identical in appearance, outfits, and even their antenna-like cowlicks.

”Whoa.”

The new creations piqued everyone’s curiosity.

”Commander, your compatibility with the Wisdom Cubes is truly impressive. When we summon Bulins, the process is far more complicated.”

Formidable and the others clicked their tongues in amazement.

”Why are there so few cubes?”

Setsuna still felt unsatisfied.

”Didn’t I tell you to produce 6,000 Bulins? Ten isn’t nearly enough.”

”Meow meow meow?!”

Akashi jumped up in protest.

”Commander! The production of Wisdom Cubes is an extremely complex process. Do you expect me to make 6,000 cubes alone?! That’s exploitation of shipgirls, meow!!!”

”Getting ten done was already a major achievement! The rest… will take at least a year—no, two and a half years!”

”That’s way too slow…”

Setsuna pondered for a moment, then turned to the newly summoned Bulins.

”Do you guys know how to make Wisdom Cubes?”

”Burin?”

The Bulins tilted their heads in unison, thinking.

”Not yet, but if someone teaches us, Bulins can learn!”

”Perfect. Akashi, your new job is to teach the Bulins how to manufacture Wisdom Cubes.”

Setsuna patted the repair ship on the head.

”Then, the Bulins will summon more Bulins. The newly summoned Bulins can learn from the older ones, and we can create even more Bulins.”

”???”

Akashi and the other shipgirls were completely dumbfounded.

”Commander, are you speaking in tongue twisters?!”

”No, no, no. You need to think differently.”

Setsuna explained.

”Imagine this: If ten Bulins take five days to produce ten Wisdom Cubes, they can summon ten more Bulins.”

”Then, with twenty Bulins making cubes, in another five days, you’ll have forty Bulins…”

”Forty become eighty, then 160, then 320... Since our resources are practically unlimited, we’ll just keep making more Bulins.”

”The surplus Bulins can even be sent out to develop Earth’s and the Demon Slayer world’s resources. The more resources we gather, the more Bulins we can create. It’s a virtuous cycle.”

”Optimistically, if all goes well, we could create a million Bulins within six months without disrupting other construction tasks.”

”And of course, if feasible, we can use the cubes to experiment with creating new shipgirls or even mech-girls...”

”!!”

The shipgirls, used to their peaceful lives at the port, were completely stunned by the scale of Setsuna’s vision.

A million Bulins!

Even counting the tiny yellow chicks, the total population of Azur Lane’s port didn’t even reach 10,000.

”What’s the big deal? Earth is huge. A million would barely fill a single city.”

”Bulins are super workers—they can repair, mine, and manufacture military equipment. Plus, they’re adorable, so the more, the better.”

Setsuna shrugged, unfazed.

”...”

Such an audacious proposal left everyone speechless.

”Is this… a chain reaction?”

Belfast suddenly found the exponential growth pattern oddly familiar.

”Commander, are you planning to initiate Controlled Bulin Fusion Plan?!”

...