Crossover Shipgirls: Building a Dimensional Empire from Scratch

An eerie silence fell over the competition venue.

The audience members, still clutching their popcorn, had barely taken two bites before the battle was already over.

They had expected an intense showdown between the Nishizumi and Shimada styles—a thrilling back-and-forth duel.

Everyone thought Miho Nishizumi and Arisu Shimada would showcase their tactical prowess, responding move for move, leading up to a climactic 2v1 battle between Miho and Maho in the Panzer IV and Tiger against Arisu’s Centurion.

But from the match start to the conclusion took less than 10 minutes.

Ōarai’s tank unit—or rather, Ōarai’s fleet—took to the skies in anti-gravity tanks and annihilated the university team with energy weapons and guided missiles the locals had never even seen before.

The crews of the 29 Pershing tanks were still dumbfounded even as their tanks were knocked out.

The uniformed girls crawled out of their vehicles, jaws dropped as they looked up at the floating Ōarai fleet.

”WTF? This was supposed to be a tankery match! Since when did Ōarai have spaceships?!”

One of the girls couldn’t help but swear.

Arisu Shimada was completely lost, her brain essentially blue-screened.

She had fought Kuromorimine several times and understood Maho’s tankery style—using heavy tanks for cover and coordinating with Panther flanking strikes in a classic frontal crush tactic.

But what the heck was Miho doing?

Arisu didn’t feel like she lost to the Nishizumi style. She lost to superior alien tech.

You can’t beat spaceships with tanks!

She looked up, still hugging her teddy bear, and locked eyes with Miho, who was descending from the sky.

”...”

”Did we go too far?”

Miho and her crew gently landed in front of Arisu.

”How was I supposed to know guided missiles were this OP?! They even have auto-targeting?!”

”I just tapped the screen twice and wiped out the enemy?!”

Hana Isuzu protested loudly, swearing she had only tapped the interface a couple of times.

[Activating Radar Targeting System]

[Target Locked. Launching Missiles.]

And then—entire enemy team wiped.

”Yaaaay! That was awesome! Who knew tanks could actually break atmosphere?! Did they install an orbital cannon on the Jagdpanzer or what?!”

Student Council President Anzu Kadotani climbed out of the Jagdpanzer, chomping on sweet potato snacks and thumping the tank’s roof with glee.

Soon, other teammates rumbled over in their tanks to join the gathering.

”Uh... congrats, Miho?”

Even Maho was unsure how to summarize the battle.

This wasn’t so much Nishizumi-style overwhelming firepower as it was using futuristic alien tech to obliterate stone-age warfare.

”How did your tanks end up like this~~?”

Darjeeling, Katyusha, Kei, Anchovy, and other school commanders all asked the same question.

Arisu also jumped down from her Centurion, standing in front of Miho and staring at her in confusion.

”Uh... well, it’s a long story...”

Miho hesitated.

She honestly had no idea where Formidable, Victorious, and those shipgirls had come from.

At the time, she had acted out of desperation to save Ōarai, and had handed over the tanks without thinking it through.

She never imagined they’d be modded into such over-the-top monsters.

Miho was now genuinely worried that the Sensha-Dō Federation or even the military would come after her for unauthorized contact with extraterrestrials.

She might even get hauled off for scientific experimentation.

”But with how things turned out... does this mean Ōarai won’t be shut down after all?”

Just as she was about to confirm things with the referee and education officials...

Suddenly, the crowd erupted in noise. On the bleachers, Shiho Nishizumi, Chiyo Shimada, and several other heads of families didn’t even have time to comment on the match. They hastily stood up to answer calls.

It looked like they were confirming something urgent.

”Check the news, Miho!!”

Several tankery girls waved their phones, calling the others over.

”??!!”

Arisu Shimada, Maho, and Miho all pulled out their phones.

They didn’t need to dig—every site, every social media feed was flashing breaking news.

The United Nations had ceded sovereignty to the Starsea Empire and acknowledged its status as their suzerain.

Major world powers had already declared surrender and accepted all the Starsea Empire’s conditions.

And the photos accompanying the headlines? All familiar faces to Miho.

The same aircraft carrier sisters who had modified Ōarai’s tanks just last night.

Formidable, Victorious, Essex—a group of shipgirls—were pictured signing agreements with world leaders.

From now on, this version of Earth would be a vassal state governed by the Starsea Empire.

Some parts of the treaty were also revealed.

Most of it was full of technical or geopolitical language the girls didn’t understand.

But one section stood out: the management of tankery.

The Sensha-Dō Federation would be dissolved. All academies would be converted to Starshipery Schools. Outstanding students would have the opportunity to study at the Starsea Empire’s Starfleet Academy.

”...”

”They were the ones who modified your tank?”

Maho pointed to her phone screen—a photo of Formidable shaking hands with the president of the Eagle Union.

In the image, Formidable stood confidently with several other shipgirls and a few Universal Angels behind her, all towering over the president.

Their empire crests gleamed on their military uniforms.

The president and other top officials were hunched over signing documents, looking like they had just surrendered.

”Uh, yeah, that’s her...”

Miho recognized the twin-tailed, silver-haired shipgirl at once.

”???”

”So your tank was modded by aliens?! That explains everything!”

Erika was stunned.

”Wait, does that mean... they came to conquer this world?!”

”Miho, were you the one who brought aliens here?! And they didn’t, like, abduct you or anything?!”

”The news said a few small countries that refused to surrender were wiped out by the space fleet!!”

”...”

Miho scratched her head, utterly overwhelmed.

She didn’t know why the aliens helped her. Maybe they just thought it was fun? Maybe they wanted to save Ōarai?

Now, whether the school got shut down didn’t matter at all.

The UN and the Sensha-Dō Federation were already gone. The Starsea Empire now called the shots.

Tankery was abolished. Time to learn Starshipery.

Miho may have been the first to interact with aliens, but there was nothing she could do about any of it.

She couldn’t just hop into the Panzer IV and challenge Formidable to a duel, right?!

”Aaaahhhhhh—”

”Why is this happening...?!”

Miho crouched down clutching her head, totally lost.

”Let’s use Ōarai’s tanks to fight back! We’ll save the world!”

A tiny blonde girl in Soviet uniform declared.

She sat on the shoulders of an older black-haired girl.

”Katyusha, please think before you speak.”

Maho looked at her exasperated.

”You want Miho to fight those who can destroy nations? Who fly kilometer-long starships? With her modded Panzer IV?”

”Eek—”

Katyusha recoiled from Maho’s glare, falling silent.

”So... what do we do now?”

Erika looked around. No one cared about the tankery tournament results anymore.

The stands had devolved into chaos. Even the referees and JSDF officers tasked with maintaining order had forgotten to declare the match results.

Everyone was glued to their phones, reading the news with a mix of disbelief, anxiety, and reflection.

Nobody was paying any attention to the girls who had just finished the match.

”...”

”Hey?! Can someone help us tow these tanks?! We kind of broke a lot of them here!”

Several girls waved frantically at the event staff.

No response.

”Hello?! Anyone?! Can someone get these tanks back to the garage?!!”

Just as they were shouting—

WMMM—

The sky suddenly darkened. A massive shadow eclipsed the sun.

The familiar silvery-white starship slowly descended from the sky. The frantic crowd instinctively stopped in place, silently raising their heads.

It was a massive aircraft carrier, ivory in color, with the Starsea Empire insignia painted boldly on its sides.

Its sheer size dwarfed the entire arena.

Hovering above it were more than a dozen other starships, both large and small.

This time, the fleet had disabled its optical camouflage, proudly and openly displaying its power for all to see.

”That’s the ship!!”

Miho nearly jumped.

Click—

The starship hovered to a stop near the tankery girls.

A long boarding ramp extended from its hull, unfolding all the way down to the ground.

Formidable, Victorious, and several accompanying shipgirls slowly walked down the ramp.

They stopped in front of Miho, smiling gently.

”We meet again, little Nishizumi~”

”Allow me to reintroduce ourselves. We are the Starsea Empire’s Expeditionary Fleet.”

”The Commander is very interested in you all. Come with us and meet him, won’t you?”

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