Crossover Shipgirls: Building a Dimensional Empire from Scratch

After Gudako left piloting the Strelitzia with the Chaldea Squad charging ahead, the other strike squads each accepted their missions and dispersed in different directions.

”Alright then, Great Tomb Squad, listen to my command.”

”Shalltear and the Pleiades, follow me to subjugate Greed first, then we’ll move to conquer the kingdom.”

”Antilene, Evileye, Lakyus… you go eliminate Sloth, then rendezvous with us afterward.”

Albedo efficiently distributed the Great Tomb Squad’s assignments.

”Huh? I’m going after Sloth? Seriously?”

Antilene pointed to herself and then glanced at the blonde, nation-destroying loli beside her, both wearing incredulous expressions.

After a moment’s thought, she shrugged. ”Alright, fine. That guy doesn’t look that tough anyway. Good warm-up.”

The group activated stealth magic, their figures flickering and vanishing as they leapt between buildings, disappearing from view within seconds.

”Night Raid Squad, we’ll go investigate that assassination organization connected to the Witches of Sin. As assassins, we can’t afford to lose to anyone.”

”Demon Slayer Corps, follow me to hunt the Great Rabbit. Prepare the super-tier spell scrolls—don’t drag it into a prolonged fight.”

”Konosuba Squad… uh, do whatever makes you happy. Maybe wander around the capital first?...”

Some chose to hunt magical beasts, while others decided to assess the situation first.

Iris glanced at her squad. The Konosuba group was large—not just adventurers, but also Yunyun, Megumin, Cecily, and a bunch of Crimson Demon girls.

The Crimson Demon girls had insisted on joining the expedition, and now that they’d arrived in another world, they were chattering excitedly in chaos.

Having joined the Starsea Empire only recently, they lacked discipline and treated the operation more like a field trip.

Considering it would be unsafe to take so many people into battle, Iris decided to relax in the city first, do a bit of ”fishing,” and get a sense of the area.

Meanwhile, outside the city, in the forest.

The Demon Slayer Corps led by Kanae were moving swiftly through the woods.

”Hm… to be safe, let’s start with some of the simpler recruitment missions.”

Kanae opened her holographic interface, reviewing the two missions she had accepted:

[Recruit Ram & Rem] and [Recruit Emilia].

The Demon Slayer Corps didn’t have as many members as the Great Tomb Squad, and unlike the Chaldea group, they didn’t suddenly pull a Gundam out of nowhere.

They planned to complete their missions steadily.

From what Kanae knew of the Commander, those girls were bound to be important.

Of course, another reason was that for the Butterfly Sisters, extra rewards weren’t really necessary.

They frequently spent nights aboard the Eternal Snowfall; whenever they wanted something, all they had to do was snuggle into the Commander’s arms and act cute.

No man could resist a girl’s request in such a moment.

Thus, the Butterfly Sisters were rather laid-back about competition, treating this more as training.

”...I still want that though…”

Nezuko and Mitsuri pouted pitifully.

”Ahem. Opportunities are created, not given… Let’s just focus on the mission first, okay?”

Kanae coughed lightly, steering their attention back to business.

”Ram and Rem should be in the Kingdom of Lugnica, at the mansion of the Margrave Roswaal on the border…”

”We’ll go negotiate there. There’s also—”

As Kanae was planning the route, something caught her eye.

The location marker for Ram and Rem on the holographic map was strange—it wasn’t where she expected.

The coordinates provided by Sophon were never wrong.

”Hm? What’s this? A small village hidden in the mountains?”

Kanae stopped walking, looking puzzled.

”Why would Ram and Rem be here?...”

”Wait! What time period are we in right now?!”

The girl froze.

When they first landed, everyone was busy dividing up missions—and Gudako’s sudden display had distracted them.

They had forgotten something obvious, something that Setsuna always insisted on before every expedition—

—Confirm the current world timeline.

”Ahhhhh—!”

Kanae quickly checked with Sophon, then looked up at the setting sun in shock.

Kanae immediately called out to her teammates, casting several acceleration spells on herself.

”Quick, quick, quick! There’s still time!!—”

...

The Dragon Kingdom of Lugnica, borderlands.

Hidden deep among the towering mountains was a small, secluded village.

Technically, this area was under the jurisdiction of Margrave Roswaal, but due to its remote location, the lord rarely paid any attention to it.

The inhabitants of this village were demi-humans known as Oni—members of the horned demon race.

In the Re:Zero world, aside from pure humans, many intelligent races lived together in various settlements.

They resembled humans in appearance but bore horns on their heads, granting them superior magical aptitude and physical strength.

Whoosh—whoosh—

It was late at night. The village lay quiet, its people fast asleep.

”Ugh…”

Inside a small wooden house at the edge of the village, a little girl with short blue hair stirred from her dreams, half-awake.

She blinked groggily, sniffing the air—it carried an odd mix of tar, iron, and blood.

From outside came faint sounds of crackling flames and collapsing wood.

Her sister, who usually slept beside her, was nowhere to be seen.

”Mm…”

”Sister?”

The small girl rubbed her eyes and stepped barefoot onto the floor.

She called out twice, but there was no reply.

Gently, she pushed open the door.

Boom—

A scorching, bloody stench rushed in.

”...!”

Rem froze on the spot.

The once peaceful Oni village had already been engulfed in flames.

Men wearing strange uniforms were swinging their weapons, mercilessly slaughtering her kin.

The elders and familiar villagers fell one after another beneath their blades.

The Witch Cult.

The infamous cult that worshipped the Witch of Jealousy—an organization of madness and blood.

They were acting under the orders of their Gospel, launching an assault on the village.

Every Oni they encountered was cut down without mercy.

”...”

The girl stood there trembling uncontrollably.

Overwhelmed by terror and shock, she couldn’t move—couldn’t even think to run.

Shua—

A group of robed Witch Cultists surrounded her, raising their weapons high.

Clang—

A petite girl with short pink hair in a nightgown suddenly jumped in front of her.

Bang—

Ram thrust out her hand, releasing wind magic. Several sharp wind blades slashed the enemies to pieces.

She darted through the crowd, small but deadly—born a once-in-a-century genius among the Oni.

In just moments, she had wiped out the nearby attackers.

”Sister!”

Rem cried out instinctively.

”Rem, thank goodness you’re safe…”

Ram turned back, reaching out her hand to pull Rem up.

Suddenly—

Shua—

One of the Witch Cultists who had fallen nearby suddenly sprang up.

A blade flashed, aiming directly for Ram’s horn.

At such close range, no one could react in time.

For the Oni, losing a horn meant losing most of their power—reduced to a shadow of their former selves.

But that fatal strike never landed.

Clang—!

A sharp metallic sound split the air as the blade was intercepted mid-swing.

When Rem dared to open her eyes again, she saw a long-haired girl in black standing before her, sword firmly holding the enemy’s strike at bay.

”You—deal with the others.”

Kanae turned her head slightly, and Kanao, Shinobu, and the others unsheathed their swords, joining the battle.

They moved like shadows, cutting down the cultists one by one with graceful precision.

Their weapons—upgraded to Xuanyuan Swords during their Taixuan training—combined with divine equipment and augmentation factors, made them far stronger than ordinary humans.

Before long, every Witch Cultist in the area was slain.

”You are…?”

Ram stood protectively in front of Rem, eyeing Kanae cautiously.

”Hmm…”

Kanae examined the two little girls—one pink-haired, one blue-haired—then stepped forward and gently patted Ram on the head.

Her natural big-sisterly aura immediately eased Ram’s tension.

”Don’t be afraid. We’re here to save you.”

She opened her holographic interface.

”Commander, reporting good news—we’ve found Ram and Rem.”

”Uh, but the timeline here seems a bit early? They’re still lolis…”

”...”

”…Isn’t that even better?”

...

”Oh.”

Aboard the starship, Setsuna received Ram and Rem, who had been sent back by the Angeloids.

The Demon Slayer Corps still had missions to carry out, so their newly recruited companions were directly transferred aboard.

The two little girls, one in front and one behind, both wore shrine-maiden-like casual clothes and over-the-knee white stockings.

They had identical short hairstyles—one pink, one blue—and equally colored eyes.

The young Ram and Rem had not yet started covering one eye like in the future, and both looked utterly adorable.

Ram walked in front, Rem followed behind, cautiously observing their surroundings.

Strangers, an unfamiliar place, and a ship flying in the sky—all of this was beyond the comprehension of two little Oni girls who had lived their entire lives in a remote mountain village.

”Um… where is this…?”

Ram, believing Setsuna to be the leader here, mustered her courage to ask.

Rem timidly followed behind her.

”Hmm, simply put, this is the Starsea Empire. One of our strike teams happened to discover your village under attack.”

”So we lent a little help. Don’t worry, we mean no harm.”

Considering their young age, Setsuna gave a brief and gentle explanation.

He stepped forward, patted Ram’s head, and handed each of them a few candies.

A horned Ram—truly a rare find.

In the Re:Zero world, a horned Ram’s potential power was among the highest tiers—her future was limitless.

”Mm…”

Remembering that this man had saved their elder sister, Ram and Rem relaxed slightly.

”Star…sea Empire?”

”Is it bigger than Margrave Roswaal’s lands? Is it like the kingdom?”

Ram tilted her head curiously. Their village had originally belonged to Roswaal’s domain.

To the little Oni, both the Margrave and the distant Kingdom of Lugnica—spoken of only in legends—were the largest powers she could imagine.

”No, both of them will one day be part of the Starsea Empire.”

Setsuna smiled and pointed through the viewing window, down toward the slowly rotating planet and the vast starry void beyond.

”Look. The Kingdom of Lugnica lies on the eastern continent. Roswaal’s territory borders it. This entire planet—and even this universe—belongs to the Starsea Empire.”

”Waaah—”

Ram and Rem pressed their faces against the glass. Only now did they realize they were in outer space, orbiting a shining world below.

Even if they strained their eyes, it was impossible to locate the small village they once called home.

”Kingdom, continent, planet, universe…”

An unimaginably vast empire began to take shape in the hearts of the two little girls.

”You’ll stay here for a few days. Once everyone’s gathered, I’ll take you to the capital.”

”Hmm… Beifa, add two new maids to your team.”

After a brief thought, Setsuna summoned the head maid.

Ram and Rem were, of course, to be trained as personal maids.

”Alright… fine.”

Beifa thought that the Commander’s maid roster was already a mix of all kinds—royal maids, dragon maids, Pleiades members, catgirls, and now two little Oni girls—so adding a pair more made no difference.

”Come, let’s get you both cleaned up, changed, and fed.”

”I’ll tell you more about this place after that.”

The head maid crouched gently, pinched the cheeks of the two little girls, and smiled kindly.

”Oh…”

Ram and Rem had no other choice. Their village had already been destroyed by the Witch Cult, leaving them homeless.

Silently, they followed Beifa.

Before long, their arrival caused quite a stir among the royal maids—who immediately rushed over to surround the two little Oni girls.

”So cute!!! Just as adorable as Little Bel and Little Cheshire!!!—”

”They’ll definitely become wonderful maids someday! Huh, does the Commander have a thing for sisters or what?…”

”You can use magic, right? Can you show us something?…”

”Uuh!”

Ram and Rem quickly realized these big sisters were way too enthusiastic.

...

After securing the first successful recruit, the Demon Slayer Corps settled Ram and Rem safely.

Setsuna continued watching the other squads’ performances through the holographic screens.

Each squad had a completely different operating style.

The Demon Slayer Corps and Night Raid preferred not to cause too much commotion. Skilled in special operations, they continued searching for Emilia and others with Sophon’s assistance—while also gathering information about the Witches of Sin.

Those figures were essentially the hidden final bosses of the Re:Zero world—far beyond what the strike squads could handle. Thus, they decided to focus on intelligence collection and report to the Commander.

Meanwhile, the Konosuba Squad was idling around the city with the Crimson Demon lolis. Setsuna suspected they’d either accomplish nothing—or cause something truly chaotic.

As for the Chaldea Squad—they were flying around in their Gundam, preparing to beat up the locals.

But the most audacious and flamboyant of all was the Great Tomb Squad.

On an open field outside the city, Albedo was addressing the Guardians and the Pleiades Battle Maids.

”Since we are here as the Supreme’s emissaries to conquer this world, we must show the dignity and might befitting His name. We must not bring the Supreme any shame.”

”Even when subjugating the Witch Cult—the lowest and most despicable of enemies—we shall demonstrate our power and announce our existence to the world.”

”Understood!”

The Guardians and battle maids took out their scrolls and began chanting summoning incantations.

Grand Display—that was one of the most important lessons they had learned from Setsuna’s expeditions.

When unsure how to conquer a world, they only had to remember how the Commander had done it before:

Show the natives overwhelming power, make them kneel, then eradicate all who resist.

Even without Gundams or starships at hand, the Great Tomb Squad had plenty of ways to put on a terrifying show.

—And that was all it took to awe a magic-bound civilization.

Boom!!!

At the borders of the Lugnica Kingdom, a violent magical storm erupted.

Originally, few Guardians or Pleiades members specialized in summoning, but during Setsuna’s re-creation process, following his ”never short on resources” principle, he had upgraded every one of their abilities.

Each of them carried countless scrolls and magical artifacts.

In an instant, the skies darkened. High-tier summoning magic saturated the atmosphere, disturbing the world’s mana balance.

Magic gathered visibly in the air, swirling downward like a vortex.

At the Roswaal Mansion, Margrave Roswaal—clad in his trademark clown-like attire—stared toward the horizon, his expression frozen in shock as he sensed the immense, indescribable power gathering there.

As a skilled magician, he was extremely sensitive to fluctuations in magical energy.

”The Witch Cult? No… no, what is this…?”

He frantically flipped through his Gospel—the book said to foretell the future—but found no mention of this phenomenon at all.

Events were rapidly spiraling beyond his comprehension.

Shua—Shua—

Brilliant, multicolored lights flashed one after another.

From the Overlord world, countless monsters and undead legions were being summoned from the ground, from the void, from massive rifts in space.

Clatter—

The first to emerge were thousands of Death Knights—each armed with a shield and sword.

They emanated a chilling aura of death, forming out of rolling black mist.

Durable, simple to summon—they were the Great Tomb’s most common unit.

Next came an equal number of Dreadmares—skeletal, horse-like abominations, each one powerful enough to annihilate a kingdom in the Overlord world.

The Death Knights mounted the Dreadmares, pairing up to become the fearsome True Death Knights.

Roar!!—

Massive skeletal dragons clawed their way up from the ground, spreading their wings to soar through the sky—forming the aerial force of the undead army.

Their levels weren’t particularly high, but their appearance alone was spectacular—perfect for terrifying the natives.

Alongside them came countless skeleton soldiers and undead mages, clad in silver and gold magical armor, wielding spears, swords, and crossbows—identical to the ones Ainz used to flaunt before the lizardmen.

Tens of thousands of skeletal warriors stood in perfect formation, resembling a disciplined army from an age of cold steel.

Ordinary people who merely looked upon this bone-clad legion would lose their courage on the spot.

The skeletons formed the vanguard, the Death Knights took the flanks, and in the center marched strange demonic entities—some of them high-level creatures.

Above them flew the bone dragons and gargoyles, completing the undead host.

Hum—

The sheer miasma radiating from this army turned the surrounding land and forest into a barren wasteland.

Albedo, Shalltear, and the Guardians rode at the front, surveying the hundreds of thousands of undead troops with satisfaction.

Nearby villages, upon witnessing the sight, immediately sounded alarms and fled in terror.

”Heh, even without the Supreme’s direct intervention, this world’s inhabitants are nothing but ants before us.”

Albedo chuckled softly.

”Ritsuka Fujimaru? Hmph, mere child’s play. We are the Commander’s most powerful squad. Let us show the world the might of the Supreme.”

Shua—

She waved her hand.

”Purge all enemies! In the name of the Supreme, conquer this world!”

Clank—clank—ROAR—

The sounds of armor, howls, and roars merged into a single cacophony.

The vast undead army began its slow, thunderous march forward.

”...”

Aboard the starship, Setsuna, Tohru, and the others watched with complex expressions.

They had focused so much on the individual strength of the squads that they’d almost forgotten the Great Tomb’s true power—their legions of undead.

”What is this? A full-scale Overlord invasion of Re:Zero?…”

”An undead apocalypse, huh…”

—

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