Crossover Shipgirls: Building a Dimensional Empire from Scratch

Clack—

An Angeloid placed several stacks of books and documents on the table.

Among them was the Book of the Dead, which the Konosuba Squad had previously recovered from the Pleiades Watchtower.

”In the current timeline, all the nations of the Re:Zero world and every recruitable ally have been secured.”

”The only ones left,” Setsuna said as he projected images on the holographic display, ”are the eight Witches of Sin.”

”Envy, Greed, Wrath, Gluttony... Their titles resemble those of the Archbishops of Sin, but their authorities are far stronger.”

”Additionally, there’s one hidden figure—the Witch of Vainglory—and a mysterious being known as the Warlock of Melancholy.”

”They’re the masterminds behind many of Re:Zero’s historical events—the Demi-Human War, the creation of the Three Great Witchbeasts, and so on.”

”Dealing with them will mark the true completion of our conquest of the Re:Zero world.”

The Book of the Dead contained records detailing the lives and deaths of every Witch of Sin except the Witches of Envy and Vainglory.

Unlike the deranged Archbishops, most of the Witches were not completely insane. Their deaths, however, were all bizarre—

The Witch of Pride drowned, the Witch of Lust was burned alive, the Witch of Gluttony died of thirst, and the Witch of Greed was slain by the Witch of Envy, among others.

The Witches of Sin were all far stronger than their Archbishop counterparts, each possessing a unique and terrifying Authority.

The Witch of Envy’s power rivaled that of Reinhard; she had once devoured half the world and was the one who granted Natsuki Subaru the ability of ”Return by Death.”

The Witch of Lust could make anyone who laid eyes on her fall hopelessly in love.

The Witch of Greed possessed the Book of Wisdom, a divine artifact that recorded all information in existence. The Gospels of Roswaal and the Archbishops were merely its imperfect replicas.

”Whoa...”

The others stared in awe.

On the surface, Re:Zero’s story revolved around the main characters’ battles of wits with the Archbishops of Sin.

But the Witches of Sin were the real legends—the shadowed figures behind the world’s tragedies. Aside from the Witches of Greed and Envy, few ever appeared directly.

Only the Book of the Dead provided fragmented accounts of their histories.

Many of them had once been ordinary people, only becoming ”Witches of Sin” after awakening their Authorities.

”Are we going to defeat them?”

Megumin raised her hand.

”The Herrscher of Sentience said she found the Witch of Envy’s seal location through Volcanica’s memories, and that unsealing it isn’t difficult.”

”So we go there, release the Witch of Envy, and then...”

The Crimson Demon lolis were clearly eager—they still regretted not finishing their last grand plan before the Commander intervened.

”The Witch of Envy? Hmm, according to this data, her strength is on par with the Sword Saint, Reinhard? Then she’s not much of a threat.”

”Supreme One, please allow me to handle her!” Shalltear volunteered eagerly.

”Stop. Do you even realize how expensive it is to revive you?! Just because we have plenty of resources doesn’t mean we should waste them.”

Setsuna waved her off, rejecting Shalltear’s self-destructive enthusiasm.

He suspected this woman just wanted an excuse to have him personally resurrect her—so she could cling to him afterward.

”Our main objective is to recruit the Witches of Sin—before they lose their sanity.”

”Their Authorities, as well as their ability to bestow them upon others, are fascinating and worth studying. They could even form the foundation for a new magical discipline at the Imperial Academy.”

Mio nodded in agreement.

”Yes, I’m very interested in the Witch Factors. They can directly grant a person an Authority... Dear, are you thinking of forming a Witch Corps in the future?”

”...”

Everyone’s expressions turned strange.

”So even the Witches aren’t safe from you?!”

”You’re just thinking the Witches of Envy, Greed, and Vainglory are beautiful and want to do things with them, aren’t you?!”

Gudako narrowed her eyes in suspicion.

”It’s called curiosity—you wouldn’t understand.”

Setsuna flicked her forehead lightly.

”...”

”So, what’s the plan of attack?”

”Most of the Witches are already dead. The Witch of Envy is sealed, the Witch of Vainglory is missing, and the Witch of Greed exists only as a spiritual entity...”

”If we want to find the survivors, we’ll need to contact the Sophons...”

Tohru tilted her head.

”That won’t be necessary,” Setsuna replied after a moment of thought.

”Let’s follow the same method we used during the Date A Live campaign—capture the key targets first, then use temporal traversal to reach them before they descend into madness, and bring them over one by one.”

”Go. Have the engineering corps prepare the Spiritron Transfer Device. Mio, Tohru, Elma—get ready.”

”This mission will be yours. Bring all the Witches of Sin to me.”

Since he had already decided to let his subordinates handle the Re:Zero world conquest, Setsuna saw no need to intervene personally. The Witches might be powerful, but his side had plenty of high-tier combatants.

”Understood.”

Tohru and Mio agreed without hesitation. Elma clicked her tongue, twirling the trident in her hand.

”Commander, the Witches of Sin are evil beings, aren’t they? You’re asking me to recruit them...”

”I’m worried I might accidentally destroy them instead...”

”...”

Setsuna thought for a moment.

”If you complete the mission, Erina and Sonoka Kikuchi will make you a feast—any dish you want.”

”—Thank you for the meal!!! Ah, I mean—Mission accepted!!!”

...

A few days later.

In the royal capital of the Kingdom of Lugnica.

The once-glorious royal palace had been flattened by the Bulins and Angeloids, replaced with a Starsea Empire–style administrative complex.

The Sophons oversaw operations within, managing affairs from across the conquered nations.

The surrounding area had been completely cleared, guarded by Battle Angels.

At the center of the plaza stood the massive, spherical Spiritron Transfer Device.

Originally, building one of these had taken a long time—but after several uses, the colored Bulins had become skilled technicians.

They now pre-fabricated parts in warehouses, then transported and assembled them on-site for instant deployment.

”System self-check... Passed.”

”Space-time curvature calibration... Passed. All systems normal.”

Observer adjusted data on the console with her tentacle-like rigging.

”Commander, this world’s conquest went smoothly! According to coordinates from the Harbor, Temperance and her fleet are almost here—they’re waiting for us to welcome them~”

Ever since she’d been ”trained” aboard the Eternal Snowfall, this mischievous little loli had become much more obedient—she even spoke to Setsuna with a soft, coquettish tone.

”Relax, we’ll finish dealing with the Witches of Sin soon enough.”

Tohru cracked her knuckles eagerly, standing at the teleportation point.

Beside her were the Spirit of Origin, Mio, and the now food-motivated Elma.

The purple-haired dragoness was already thinking about what dishes she’d have the culinary squad prepare to celebrate their return.

”I can’t let those other girls outshine me...”

Mio smiled sweetly. After seeing how active the other squads had been in their world conquests, she had decided to show her own brilliance this time.

[Reverse Summoning System: Activated]

[Initiating Spiritron Transfer... Target World: Re:Zero – Starting Life in Another World]

[Transfer commencing in...]

”5... 4... 3... 2... 1...”

[Transfer complete!]

Vmmm—

With a mechanical hum, Mio, Tohru, and Elma’s bodies flickered between solid and translucent, then broke apart into countless blue particles that dissolved into the air.

...

Whoosh—

When the three opened their eyes again, they found themselves in a completely unfamiliar city.

Medieval-style architecture lined the streets, with simply dressed townsfolk and livestock wandering freely among the cobblestone roads.

In this sword-and-magic world, technology seemed utterly stagnant—as if the march of centuries had long forgotten to move forward.

”Hmm...”

Mio, the squad leader, opened her holographic interface to check their target data.

”Let’s move quickly. We wouldn’t want to keep the Commander waiting.”

”Let’s see... First, we’ll deal with the most troublesome one—the Witch of Vainglory.”

The Witch of Vainglory was the founder of the modern Witch Cult and the true mastermind behind many of the world’s disasters.

At this point in time, it was unclear what state she was in.

”If she’s willing to surrender and promise not to cause trouble anymore, great. If not...”

Tohru cracked her fingers with a clack.

”I’ll make her willing.”

Flash—

After pinpointing the target’s exact location on the map, the three vanished in an instant.

...

In the Elior Forest.

Compared to the frozen forest hundreds of years later, this forest had not yet been affected by Emilia’s uncontrolled magic—everywhere it was lush and green.

A few scattered spirit tribes lived quietly among the trees, leading peaceful lives.

Humming…

A faint, wandering tune drifted through the woods.

A girl in pure white, her expression both calm and languid, strolled through the forest.

Her beauty was natural, unadorned. She wore a simple white robe carelessly draped over her shoulders, exposing one delicate shoulder.

Platinum hair fell to her waist, unstyled but remarkably smooth. Her pupils were an otherworldly blue, and her eyebrows matched her hair in color—giving her an ethereal, dreamlike air.

She walked barefoot, humming strange snippets of melody as she went.

Not a speck of mud or dirt clung to her.

As she walked, the grass ahead trembled.

Rustle, rustle—

A group of robbers sprang up from the undergrowth, clutching crude axes and knives, wearing makeshift armor.

They were a mixed lot—humans and demi-humans.

In a remote forest, a lone girl meeting highwaymen was nothing unusual.

”Hey, lucky day…”

The leader eyed the girl up and down.

Her clothes were clean; her face pretty—maybe the daughter of some wealthy household.

Kidnap her and they’d be set for life. And maybe have some fun along the way.

”Listen, little miss—if you behave...”

A lizard demi-human spoke in a hoarse voice.

”...”

Pandora paused, smiled faintly.

”And if I don’t?”

”You won’t have a choice...”

A tall demi-human clapped a hand onto her shoulder, intending to seize the small girl.

Unexpectedly, she didn’t move a muscle.

Beneath her frail appearance lay a tremendous power.

Clack—

The girl placed a hand on his arm.

Tilting her head, she said in a flat, haunting tone:

”You should already be dead, shouldn’t you?”

”What nonsense are you talking about?”

The leader drew his blade with a snarl, planning to teach her a lesson.

The girl lifted her chin and spoke calmly:

”You killed all your companions—you cut off their heads with the knife in your hand, didn’t you?”

”What—?!”

Time seemed to freeze for a moment.

The blade that should have slashed Pandora instead cut down the man next to him—precisely, inevitably.

He moved with absolute resolve and speed, severing his comrades’ heads one by one.

This was an inevitability—a prophecy. When a witch spoke a prophecy, it came to pass.

Blood sprayed through the air.

In an instant, there were several corpses on the ground.

The blade-bearer collapsed from exhaustion, breathing heavily, and turned to look at the massacre behind him.

Suddenly, he snapped awake.

”Mon—monster!!”

”You’re a witch!!!”

He cried in terror.

”Eh? You just noticed?”

The girl stepped forward and pressed a hand to his shoulder.

”You’re already dead, too.”

”You should be using that blade to end yourself right now.”

Slash—

The man obeyed, cutting his own throat. He twitched painfully on the ground for a moment, then went still.

Only scattered corpses remained.

From start to finish the girl hadn’t moved a muscle—she had only spoken a few words.

”Boring...”

Pandora shrugged and continued on her way.

She had seen this same sequence countless times before.

Killing these weak, defenseless people held her no entertainment.

Suddenly—

Whoosh—

Not far ahead, a blue portal opened.

From it stepped a silver-haired girl of breathtaking beauty, flanked by two dragon girls.

”Oh...”

”Confirmed—Witch of Vainglory, Pandora.”

”Authority: the power to alter reality through spoken words. Activation conditions unknown. Limitations unknown.”

The trio observed the girl before them carefully.

In the chronicles of the Re:Zero world, she was little more than a mystery—a shadow in the background. All that was known was that she had founded the Witch Cult.

Over a century before the main story began, Pandora led the Witch Cult in a surprise attack on the Elven Forest, triggering Emilia’s loss of control.

She also incited the Demi-Human War and assassinated both sides’ negotiators during peace talks.

Her motives were unclear, and she was behind countless events throughout history.

Perhaps it was simply the nature of witches to possess a morality unlike that of ordinary people—what others saw as atrocities, they might view as mere curiosities or passing amusement.

”...Who are you?”

Pandora blinked in confusion at the Spirit of Origin and the dragon girls standing before her.

”We are from the Starsea Empire. In the past, present, and future, we shall conquer this world.”

”Pandora, my dear husband—ah, no, our Commander—is quite interested in you and the Witches of Sin. Would you care to come with us?”

Mio, unaccustomed to speaking with strangers other than Setsuna, decided to get straight to the point.

”...What?”

Pandora tilted her head, clearly not understanding.

”I don’t know who you are, but ’conquering the world’? Such arrogance...”

She examined the trio more closely, sensing their aura—and her curiosity was piqued.

”You’re witches too? ...No, that’s not right. You don’t feel like Echidna or the others... elves, perhaps? No, not that either... Are you from another world?”

Being a witch, Pandora instantly sensed that the magic flowing from the three before her was completely alien to this world’s system.

Instinctively, she wanted to know more.

”Come now, tell me—where do you come from? What is this ’Starsea Empire’ you speak of?”

Her lips curled into a faint smile as she reached out to touch Mio, activating her Authority to probe for information.

”Oh my... seems this witch lady has some strange ideas, doesn’t she?”

Mio caught Pandora’s hand gently.

[Ain-Soph (Paradise of Samsara)]

Whoosh—

The world instantly turned black and white.

Sky, earth, and time itself froze.

Everything within sight was drawn into Mio’s Domain of Reincarnation.

”This is...?”

Pandora’s eyes widened in disbelief.

She had always been confident in her power, yet now she found herself in an incomprehensible space—trapped by the Spirit of Origin herself.

”Shall we test it?” Mio tilted her head playfully.

”The Commander said your ability resembles mine—you can rewrite reality, can’t you?”

”...?”

For the first time, Pandora’s calm façade faltered. Normally, her expression never changed beyond a faint smile—but now, genuine alarm flickered in her eyes.

”You... know my name? And my Authority? Who are you really?!”

She pressed her hand to Mio again, invoking her Authority to alter the girl’s mind.

Pandora’s power could manipulate thought and perception—she had once driven the Archbishop of Sloth insane and rewritten memories with ease.

She expected this to work just as smoothly.

But to her astonishment—it didn’t.

There was no effect at all.

The girl before her didn’t even flinch. Pandora’s Authority couldn’t so much as stir her.

In fact—it was being overridden.

”You’re the first person to challenge me in my own Paradise of Samsara.”

Mio smiled faintly and made a casual grasping motion with her hand.

”Ugh—!”

Pandora gasped as the air around her compressed, lifting her by the throat into the air.

”No... you can’t hurt me...!”

She forced out the words, attempting to negate the attack with her Authority.

By rewriting reality through willpower, she could deny any harm done to her body—effectively rendering herself invincible.

Echidna had once described her as a witch specialized for survival, and it was no exaggeration.

Magic flared violently around her, filling the air with light.

But moments later, her power faltered—flickering like a candle in the wind—then vanished completely within Mio’s absolute domain.

”!!!”

She couldn’t comprehend it.

For the first time in her existence, Pandora met something utterly beyond her understanding.

Her magic compared to this silver-haired girl’s power was like a stream before an ocean.

The so-called Authority of a witch was meaningless before the primordial being who ruled the Tree of Life—Zero.

Both could rewrite reality—but the higher Authority completely dominated the lesser.

”Looks like I win.”

Mio tightened her grip slightly.

With ordinary girls, she preferred gentle persuasion to win them over.

But this witch wasn’t ordinary—if not subdued by overwhelming force, she’d cause chaos wherever she went.

”In short, to make sure she doesn’t cause trouble for the Commander later, I’ll give her a light beating first—just in case.”

Tohru explained casually to a wide-eyed Elma beside her.

”...”

”Guh—”

Pandora choked, her body trembling.

”Now then—can you listen properly now?”

Mio’s tone softened, her expression serene and lovely, though her words carried a faintly sinister warmth.

”The Commander wishes to see you. Come with me, behave yourself, and don’t do anything bad. Otherwise, I’ll get angry.”

Thud—

She released her grip, dropping Pandora to the ground.

”Huff—huff—”

The Witch of Vainglory clutched her chest, gasping for air, visibly shaken.

”Tch, fine... have it your way.”

So terrifying... she was completely overpowered.

Whatever these beings were, she’d think twice before defying them again.

—

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