Crossover Shipgirls: Building a Dimensional Empire from Scratch

Three days later.

”Breaking news!”

”Breaking news! A renowned merchant from a neighboring country recently arrived in Osaka, claiming to be searching for the Blue Spider Lily and offering a massive reward!”

At a street newsstand, newspapers from Daily News, Asahi News, Osaka News, and other now-famous publications all featured the same story on their front pages.

The headlines declared that a wealthy merchant named Setsuna had crossed the seas to seek the Blue Spider Lily in the island nation.

In the hands of imaginative reporters, the tale grew rich with dramatic embellishments.

”Hmm, so his sister has some sort of illness that makes her unable to be in the sunlight? And only the Blue Spider Lily can cure it?”

”He’s really going through a lot for his family, isn’t he?”

Passersby gathered around the papers, casually gossiping as they read.

”Did you see? He’s offering a reward of 300,000 yen! If someone finds the Blue Spider Lily, they’ll be set for life!”

”Merchants from the neighboring country are really that rich??”

The outrageous reward caught everyone’s attention, much like modern lotteries boasting billion-dollar jackpots.

To put things into perspective, during the Taisho Era, even the prime minister of the island nation barely made 10,000 yen annually.

This amount promised a lifetime of wealth and comfort.

”But… an illness that makes you unable to see sunlight? Sounds kind of strange, doesn’t it?”

”Almost like something out of a novel about vampires?”

One young man scratched his head thoughtfully.

”I heard that demons also can’t be exposed to sunlight… Could it be…?”

While the Demon Slayer Corps wasn’t widely known, stories of their exploits had reached some ears.

”Come on, he’s from a neighboring country. They don’t have demons there. You’re imagining things.”

His companion dismissed the idea with a laugh.

The conversation was casual, but it caught someone’s attention.

A pale-faced man in a Western suit, who happened to be walking by, abruptly stopped in his tracks.

”I’ll take a copy of the paper.”

The man handed a coin to the newsstand vendor and eagerly scanned the pages.

To any observer, he seemed like a typical high-ranking salaryman.

Yet the more he read, the more his breathing quickened.

”Blue Spider Lily…”

”A cure for an aversion to sunlight…”

Familiar. Too familiar.

If Muzan had doubted the flower’s existence after centuries of failure, this article now reignited his faith.

The Blue Spider Lily had to be real. Otherwise, why would someone travel across the ocean to find it?

And the notion of curing a fear of sunlight struck him straight to his core.

If not for the risk of exposure, Muzan might have stormed into Setsuna’s residence that very moment to demand answers:

Do you have demons in your family?

”No…”

”No, stay calm. Keep observing.”

Muzan steadied his breathing, folded the paper, and walked away.

The next evening.

As dusk fell, Muzan once again stopped by the newsstand to purchase a copy of the newspaper.

The headline was still front and center.

The tale of the foreign merchant’s treasure hunt had captivated readers, and the papers were capitalizing on its popularity.

”According to plant experts accompanying the merchant, the Blue Spider Lily only blooms during the day and has a very short flowering season…”

”Over 500 people have claimed to have found leads, and experts are currently verifying the information…”

Muzan dismissed the unverified claims—he’d been deceived countless times over the years.

But one detail in the article struck him like lightning:

The Blue Spider Lily only blooms during the day.

It all made sense now.

For over a thousand years, Muzan had been searching in vain, not realizing this crucial fact.

”This… this is it!”

The revelation hit him like a divine epiphany.

He almost wanted to thank the merchant. If not for Setsuna, Muzan might have continued searching in darkness for eternity.

Of course, as the progenitor of demons, Muzan’s gratitude typically involved turning people into demons themselves.

The authenticity of the story wasn’t in question—Setsuna’s words were tailor-made to resonate with Muzan, striking at every insecurity and desire he harbored.

For the next several days, newspapers continued to provide updates on the fabricated treasure hunt.

Each article was more dramatic than the last, making the story seem increasingly believable.

When a blonde, twin-tailed girl who provided a ”lead” even claimed a cash reward, public enthusiasm hit a fever pitch.

Muzan found himself eagerly anticipating the daily updates.

Meanwhile, Setsuna’s main task was brainstorming new ways to further deceive Muzan.

Muzan originally planned to act swiftly and eliminate the merchant. Yet, after much thought, he decided to wait.

He would strike at the final moment, ensuring the situation unfolded in his favor.

One week later.

On an unremarkable evening, Muzan purchased a copy of the Asahi News as usual.

But the moment his eyes landed on the front page, he froze.

The headline blared:

”Search Party Discovers Blue Spider Lily! To Return via Tokyo Bay After Collection!”

The accompanying photograph depicted a blooming spider lily.

Though the Taisho Era’s colored photography lacked precision, Muzan could see it clearly.

It was blue.

Not the common red spider lily—it was unmistakably blue.

It was found.

Muzan nearly trembled with excitement.

He gently traced the photograph with his fingers, as if reliving the centuries of frustration and longing that had brought him to this moment.

Without hesitation, he activated his power as the progenitor of demons, summoning the remaining Upper Moons.

”Kokushibo, Akaza, Nakime, Hantengu… Assemble in the Infinity Castle immediately.”

”I have a task for you.”

Three days later, at dusk.

Northern Island Nation, offshore near Sasebo Port.

A black heavy cruiser floated silently on the ocean.

Its black-and-red hull, eight 203mm main guns, and the distinctive double-layered command tower marked it unmistakably as the Prinz Eugen-class Heavy Cruiser.

Under the cover of night, no one had noticed its presence.

Setsuna stood atop the ship’s bridge, gazing intently toward the distant coastline.

”Commander, are you sure Muzan will show up?”

Beside him, Prinz Eugen, with her silver-white hair streaked with crimson, asked curiously.

”He will. He’ll pull every string he has to seize that nonexistent Blue Spider Lily.”

Setsuna’s eyes remained fixed on the shore.

With his understanding of Muzan, he knew exactly how desperate the Demon King’s obsession with eternal life was.

According to the plan, today marked the day when the ”merchant” would embark with the flower. The newspapers had conveniently leaked the route, with the departure point set at the scarcely populated Sasebo Port.

For someone like Muzan, this was the perfect opportunity—practically a golden invitation to strike.

”Uh, but what if he doesn’t act as you expect and just hides away somewhere?”

Illustrious, standing nearby, voiced her concern.

Ever since the start of this operation, she had felt like the Commander was toying with Muzan, though whether the Demon King would take the bait was another matter entirely.

”If that happens, we’ll deal with the shogunate, haul back their resources to finish building the Gundam, and then nuke Muzan and the island into the stratosphere.”

Setsuna chuckled.

He had contingency plans—several, in fact. But for now, he wanted to try the simplest approach: luring Muzan and his entire brood out and taking them all down in one strike.

And if he could tease Muzan along the way, so much the better.

”Oh…”

The other shipgirls nodded, already prepared for battle.

Taihou and Illustrious stood on Prinz Eugen’s deck. Since the shallow waters near Sasebo couldn’t accommodate an aircraft carrier’s hull, the two would fight in their rigging forms.

At a wave of their hands, several squadrons of carrier aircraft took to the skies, heading toward the shore.

”He’s coming!”

Not long after, the reconnaissance aircraft sent back a signal.

”Clustered targets spotted 35 kilometers northwest, advancing rapidly toward the coast!”

On Land.

Rustle, rustle…

Shadows darted through the forest, their movements too fast for human eyes to follow.

Some ran like quadrupeds, crawling close to the ground. Others leaped from tree to tree like monkeys.

Only upon closer inspection would one realize that all these figures were ghouls of grotesque shapes and forms—a demon army.

There were demons wrapped in layers of grotesque arms, demons in ninja attire, arrow demons, swamp demons, and countless other lesser demons.

Under the command of their progenitor, Muzan Kibutsuji, they surged toward the coast like a nightmarish tide.

A parade of a hundred demons.

It seemed as though Muzan had summoned nearly every demon on the island.

Among the cacophony of sinister cackles and guttural growls, Muzan himself strode calmly near the rear of the horde.

The Demon King—young in appearance, pale-faced—moved with a calculated caution, constantly attuned to his surroundings.

No humans. No signs of the Demon Slayer Corps.

Originally, after the inexplicable death of Doma, Muzan had considered going into hiding for a while.

But centuries of failure, coupled with his unrelenting thirst for immortality, drove him to take this calculated risk.

If the Blue Spider Lily truly existed, then sunlight would no longer be his weakness. He would become the perfect, immortal being.

”Strange… where is the Demon Slayer Corps?”

At the forefront of the demon army marched two imposing figures.

One was a pale-skinned man with short, peach-colored hair and black markings across his face. His irises bore the kanji for ”Three.”

The other was a six-eyed man, each pair of irises inscribed with the kanji for ”Upper” and ”One.”

As the Upper Rank Demons surveyed their surroundings, they found no trace of the supposed merchant or the Demon Slayer Corps.

They weren’t particularly worried about an ambush.

As Upper Rank Demons, they could effortlessly annihilate most of the Demon Slayer Corps.

Combined with their vast army of lower demons and fellow Upper Ranks, they felt invincible.

What fool would dare challenge such overwhelming numbers?

”…”

Muzan said nothing. With a wave of his hand, the demon horde spread out, beginning a thorough search of the area.

Thanks to their heightened senses, it didn’t take long for Muzan to notice the ship floating offshore.

The heavy cruiser on the water was unlike anything he had ever seen.

Its design, its scale, and the flags it bore were entirely foreign to this era.

”What is that…?”

Muzan squinted at the sea, deep in thought.

On the Prinz Eugen.

”He actually fell for it?”

On the ship’s bridge, Setsuna peered through his binoculars at the unfolding scene onshore.

What had initially been a half-baked plan to lure Muzan out had somehow succeeded beyond expectations.

Here he was, with his entire demon army, ready for an all-out battle over a blue flower that didn’t even exist.

Clearly, Muzan’s obsession with the fake Blue Spider Lily was even greater than anticipated.

”One… ten… a hundred…”

”Commander, did you poke Muzan’s nest or something?”

Illustrious stared at the radar, dumbfounded.

Their radar, typically calibrated for naval engagements, struggled to accurately detect smaller, irregular targets like demons.

But the sheer number of demons Muzan had brought made the radar screen light up like a Christmas tree.

Some of the demons were so grotesquely shaped that the scanner couldn’t decide whether to classify them as humans, animals, or objects.

It simply lumped them all under the label of ”unknown biological entities.”

”This simplifies things. No need to dig him out of the ground.”

Setsuna cleared his throat.

”All units, open fire at will.”

”Remember: No-Ru-san... wait, no—should it be no…?”

Bang!

The heavy cruiser’s cannons roared to life, illuminating the night.