Crossover Shipgirls: Building a Dimensional Empire from Scratch

A few days later.

On the plains outside the capital.

The combat personnel stood in neat formation.

This was the second large-scale Interdimensional war. Having gained experience from the Akame ga Kill world, everyone appeared slightly more relaxed.

The shipgirls were eager and full of fighting spirit.

They looked forward to clashing their star-destroying ships against otherworldly magic.

It was a rare opportunity to perform in front of the Commander.

Normally, with hundreds of shipgirls in the port, Setsuna could only take a small portion on each expedition.

Only interdimensional wars warranted the mobilization of large fleets.

Everyone stood in formation according to class: carriers, battleships, cruisers, destroyers, etc.

Each carrier and battleship onee-san led a combat squad composed of several destroyers and cruisers.

Gudako still stood beside her Barbatos.

Next to her stood a Gundam as well.

RX-0 Unicorn.

Unicorn adored the gift Setsuna gave her and took it everywhere.

"Hey, aren't you a shipgirl? Isn't piloting a Gundam into battle kind of a waste?!"

Gudako stared at the pure white Unicorn, puzzled.

"Onii-chan gave it to me!"

Unicorn hugged Yuu-chan and tilted her head defiantly.

"I want to fight in it!"

"...As long as you're happy."

Gudako's mouth twitched.

She just hoped no poor soul damaged Unicorn's Gundam.

Otherwise, Unicorn would get angry and enter true annihilation mode.

The Heroic Spirits, Spirits, Demon Slayer squad, and Night Raid team were all ready.

Ikaros, Nymph, and Astraea—the three Angeloids—stood beside Setsuna.

"Tch, it's the United Multiverse Army."

Setsuna did a headcount.

Seeing the growing number of allies at the base, every inspection felt incredibly fulfilling.

After confirming everything, he selected the Overlord world on the star chart.

[Overlord – Tier-II Magic Age]

A world with abundant magical and supernatural powers. Powerful individuals possess the ability to destroy nations, though no deities who command the laws of the world have yet appeared.

[Power Comparison:]

Technological Level: Like an Ant.

Military Strength: Like an Ant.

Economic Power: Like a God.

[Diplomacy]

[Traversal]

[Declare War]

"..."

Setsuna remembered that the Overlord world was unlocked when humanity had just reached space due to technological advancement.

At that time, its tech and military power were still somewhat comparable. Now both were rated as 'Like an Ant.'

As for economic strength...

Well, he wished the system would use a different algorithm. His side was a utopian society—no finance, no economy.

If measured by productivity, it should also rank 'Like a God.'

He opened the communication interface first.

Zzz—

After a burst of static,

A projection appeared of a skeleton in black robes holding a staff.

Its frame was much sturdier than a normal skeleton, with a large red orb embedded in its ribcage.

In the Overlord world,

Ainz Ooal Gown sat on his throne, listening to his subordinates' report.

"Lord Ainz, we've searched the Re-Estize Kingdom, Baharuth Empire, the Holy Kingdom, and the surrounding areas, but we couldn't find the person you described."

A tall man in a British-style suit with round glasses knelt on one knee, reporting to Ainz.

A silver, metal-plated tail dragged behind him. Though he looked like a merchant or lawyer, the evil aura about him was unmistakable.

"We also consulted the Empire and Holy Kingdom's magic casters. No one here seems to possess the remote communication technology you mentioned."

"We're very sorry. Should we expand the search range?"

Demiurge bowed his head and asked.

"...Go ahead."

Ainz tapped his skeletal fingers anxiously on the throne.

Ever since Setsuna first contacted him, Ainz suspected there were other players in this world besides himself.

It was just too similar!

That opened holographic interface looked strikingly like the YGGDRASIL UI.

The human kingdoms here couldn't possibly have such technology!

Only another transmigrated player could explain it!

And that was what Ainz feared most.

Player strength typically far exceeded that of native inhabitants. If another player arrived with a guild or organization, it would be even more troublesome.

But no matter how thoroughly he searched the world, he couldn't find a single clue.

"Could it be the Six Great Gods, or the Eight Greed Kings?"

"Should we head to the southern desert?..."

Ainz flipped open a book to investigate.

According to legends from centuries ago, YGGDRASIL players had indeed descended into this world, briefly unifying the continent with overwhelming power.

But that was too long ago—only fragmented tales remained.

"..."

Just as he was considering dispatching more floor guardians to investigate—

Whoosh—

A familiar holographic interface opened again before him.

Setsuna's avatar appeared.

"Hello? It's you again?!"

"!!!"

Seeing that familiar face, Ainz was completely startled.

Whoosh—

He leapt to his feet, teleported away from the interface, and frantically cast over a dozen buffs.

"Infinity Wall," "Crystal of Holy Magic," "Essence of Life," "High-Tier Full Stats Boost," "False Life Intelligence," "Supernatural Intuition"...

"Floor Guardians, assemble!!!"

Thud, thud, thud—

The major floor guardians and Pleiades quickly gathered near the throne.

"???"

"What is he doing?"

The dragon girls and Spirits peered over curiously, watching as the skeleton flashed with a rainbow of lights, turning into a dazzling skeletal disco ball.

"Fighting the air with all his might."

It was the first time Setsuna had seen someone so terrified by a holographic screen.

When he'd contacted others before, even ordinary people like Honest were only mildly surprised.

Truly, this was the Bone King.

"Oh?"

After stacking all his buffs, Ainz cautiously approached the interface when he realized no attacks were coming and no anomalies were appearing.

He studied Setsuna and the girls beside him.

Not guildmates. Their clothing looked familiar—like military uniforms.

Which only reinforced Ainz's belief: Setsuna was definitely not a native of this world.

"Who are you?"

He quietly cast his highest-tier detection spell to probe Setsuna.

Nothing was retrieved.

The target's life, level, race—all data was completely hidden, unquantifiable by this game-like world.

"Let's cut to the chase."

"Surrender—or die."

Setsuna saw no point in small talk.

He cleared his throat and opened the war declaration interface.

[Declare war on target world and initiate interdimensional war?]

[Confirm.]

"Casus belli: Forced subjugation."

Whoosh—

At the moment Setsuna selected "Declare War,"

The interface before Ainz changed dramatically.

A star chart projection appeared, marking the positions of the Starsea Empire and his world.

Then a prompt popped up:

[The Starsea Empire has declared war on you!]

[Interdimensional War Initiated: Starsea Empire vs. Overlord World]

[Power Comparison:]

Technological Level: Like a God.

Military Strength: Like a God.

Economic Power: Like an Ant.

[Interdimensional Passage Countdown: 1 hour 59 minutes]

"???"

Ainz was shocked.

In the YGGDRASIL game, he'd fought duels, team battles, and guild wars.

He'd once participated in the largest battle against over eight guilds with more than 1500 players and NPCs.

But what the heck was a world war?!

It sounded way more high-end than guild or nation wars.

Such a thing never existed in the original game.

"Is this a new mechanic added to the game?"

As a veteran player, Ainz quickly adapted.

The system holographic interface notifying him of war resembled the way other guilds used to launch invasions.

"Wait."

"World war? Does that mean there are other worlds beyond this one?!"

A terrifying realization struck Ainz.

Smack—

He slammed his desk.

Buzz—

In the heat of his agitation,

Green light flared across his body, calming his emotions.

Setsuna's declaration of war had triggered his forced tranquility effect.

Meanwhile—

Elsewhere in the Overlord world.

Baharuth Empire.

In the palace, a golden-haired emperor in luxurious robes sat on the throne, discussing the ongoing war with the Re-Estize Kingdom with his generals.

The empire's generals and magicians were simulating troop deployments on a sand table.

"Our imperial knights are stronger than the kingdom's peasant levies. Fighting on open plains gives us an advantage."

"But we must beware of the Kingdom's Warrior Captain—he alone equals 500 knights. We'll need to deploy the Four Knights to counter him..."

While the natives were studying war strategies—

Whoosh—

A holographic interface opened before them.

Emperor Jircniv received the war declaration.

"???"

The so-called Blood Emperor was dumbfounded.

"What is this? Someone's declared war on us?"

"Is it another empire from across the continent? Why have I never heard of this name before?..."

The young emperor stroked his chin, lost in thought.

He couldn't understand it.

In this world, human kingdoms always declared war through envoys and written documents.

A holographic interface declaration was unheard of.

Not from a kingdom, nor the theocracy—this was an unknown empire entirely.

His advisors and generals were equally baffled.

"Such precise timing... Could this be reinforcements for the Re-Estize Kingdom?"

Jircniv made a chilling inference.

"Inform the frontlines to cease the offensive."

"Investigate the source of this message."

Thousands of miles away—

The Re-Estize Kingdom, locked in conflict with the empire, also received the notification.

"Could it be reinforcements from another nation?!"

The old king and his strategists reached the exact same conclusion.

Meanwhile—

The Slane Theocracy, Roble Holy Kingdom, and other nations' rulers received the war declaration simultaneously.

Even the lizardmen tribes, the Frost Dragons in the Azellisia Mountains, the Deep Darkness Dragon Lord hidden underground, the Brightness Dragon Lord—none were spared.

The ancient dragon lords, who had secluded themselves underground for untold years, stared in confusion at the war notification.

Interdimensional war meant conquering all countries and forces of this world—whether human civilizations or non-human ones.

Any intelligent, organized entity, including powerful individuals, was a war target.

On the holographic interface, Setsuna looked at the long list of war declarations he'd made.

"The Starsea Empire declares war on the Great Tomb of Nazarick!"

"The Starsea Empire declares war on the Baharuth Empire!"

"The Starsea Empire declares war on the Re-Estize Kingdom!"

"The Starsea Empire declares war on the Lizardmen!"

"..."

Two full columns of war declarations—truly a grand sight.

"Commander, they sure have a lot of people."

Yukikaze twitched her ears and stuck out her tongue.

"So what? We're the World Alliance—formed from Azur Lane, Chaldea, Date A Live, Arpeggio of Blue Steel, and more than a dozen worlds."

Setsuna patted the little shipgirl's head and comforted the nervous Butterfly Sisters.

"They'll all end up spilled like soy milk at our feet!"

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