Crossover Shipgirls: Building a Dimensional Empire from Scratch

Ka-boom—

After several days of interstellar cruising, the Eternal Snowfall successfully returned to base, landing at the aerospace facility outside Constantinople.

A swarm of Bulins responsible for ground operations rushed forward, armed with various tools to inspect the ship.

The shipgirls disembarked reluctantly, their minds still captivated by the celestial sights they had witnessed.

Yukikaze suddenly felt that her jetpack, which she had modified using Gundam thrusters, was no longer appealing.

She pulled it out for a look. That thing could only maneuver within the atmosphere and wasn't particularly fast—how could it compare to the grandeur of a starship?

Without hesitation, she ran up to Setsuna, clinging to his arm and pouting.

"Commander, Commander, when can we be transformed into starships like this one?!"

As soon as she spoke, the other shipgirls quickly gathered around, their eyes sparkling with anticipation as they looked at Setsuna.

"Uh… the technical part isn't difficult, but each of your hulls will need to be redesigned from scratch…" Setsuna pondered for a moment.

The successful launch of the Eternal Snowfall proved that the base was capable of constructing starships.

However, converting the shipgirls into starships was an entirely different matter. The design principles for starships and naval vessels were fundamentally different.

For instance, a starship required a fully enclosed hull, modular internal layouts, and space-optimized weapons.

Their current hulls would essentially need to be rebuilt from the ground up. Even aircraft carriers would need their carrier-based planes redesigned for space combat.

It was a monumental project, though fortunately, there were plenty of Bulins and resources available.

"All right, I'll find time to design your hulls. The Vanguard Fleet will go first," Setsuna said.

Having spent so much time with Akashi, he had picked up a great deal of technical knowledge and had a thorough understanding of hull structures.

Each shipgirl was unique, and it wouldn't do to use mass-production designs for their hulls.

"Yay—"

The Vanguard Fleet shipgirls cheered enthusiastically.

To them, coming to this other world to pioneer had already been immensely rewarding.

Having their commander personally design their hulls? That was the ultimate honor. A shipgirl's hull was her body—there was no greater gesture of trust and respect.

"Ah—Commander, I entrust my body to you…"

A shipgirl with twin tails, dressed in a short kimono, hugged him from behind.

She pressed herself against him, her eyes brimming with allure.

"Please feel free to modify Taihou however you like. Whatever you want my body to become is perfectly fine…"

"I think your current figure is already perfect. If it gets any bigger, you'll turn into a fat dinosaur…" Setsuna replied, feeling the pressure against his back and breaking into a sweat.

"???"

The Heroic Spirits watched with puzzled expressions. To them, shipgirls were already bizarre enough.

It was strange enough that they could transform into ships at sea and wield rigging on land. Now they could even transform into starships?

Jeanne Alter jabbed Setsuna with her finger, her tone haughty.

"Hey, Master, what about us? Can you turn me into a starship too?"

"You can't even use a Wisdom Cube… You can just accompany the fleet in the future as a special task force or something…" Setsuna replied.

Setsuna pondered for a moment. He felt that Heroic Spirits would be particularly suited for boarding actions during space battles.

No matter how sturdy an enemy's spaceship was on the outside, its internal structure probably wouldn't withstand an Anti-City Noble Phantasm.

"Hmm…?"

Jeanne Alter draped her arm over Setsuna's neck, looking every bit like a gang boss.

"So you're saying you'll take me along on your spaceship in the future? That doesn't sound too bad…"

"Make sure to reserve the best spot for me. I'll burn all your enemies to ashes," she said with a smirk.

"..."

Setsuna's expression grew strange.

Wake up, Jeanne Alter! Times have changed. You can't even beat Artoria anymore. Acting so cocky—is that really okay?!

As the shipgirls dispersed and returned to the naval base, Setsuna settled into his office to assess the gains from completing the recent mission and advancing into the Space Age.

First, the star map now featured several new neighbors.

Their strengths varied. Transformers focused on technology, Goblin Slayer and Overlord leaned into magic, and Dragon Maid seemed like a casual world with some supernatural elements.

He would need to devise plans to slowly explore and conquer these worlds.

Then there were the three mission rewards.

The Authority of Interdimensional Warfare didn't need much elaboration. Once the shipgirls were converted into starships, he would certainly find a lucky target to test it on.

As for the two architectural blueprints…

Setsuna glanced at them.

"Get Akashi over here."

"Meow?!"

Ten minutes later, Richelieu delivered the maintenance specialist into the office.

"Commander, what weird task are you going to assign me this time, meow?"

Akashi was already accustomed to Setsuna handing her strange technologies from other worlds whenever he called her over.

"Take a look at these two."

Setsuna pulled out the blueprints for the Dimensional Anchor and the Sundial Array.

Boom—

The massive blueprints unfolded, filling the several hundred square meters of the office to the brim, spilling over into adjacent rooms.

"Eh?!"

Akashi was stunned, then sat on the floor to examine them.

"Dimensional Anchor…"

"It creates rifts in space-time, allowing users to transport themselves between dimensions…"

"Commander, this is incredible, meow!"

According to the blueprint's description, the Dimensional Anchor allowed interdimensional teleportation across different universes.

For the Starsea Alliance, this was practically a necessity.

Currently, any interaction with other worlds required Setsuna to personally open the portal.

Ning Hai and Ping Hai needed Setsuna's personal intervention to collect taxes from the Demon Slayer world. If the shipgirls at the port wanted to visit or immigrate to this world, it also required him to personally open the portal.

Even Gudako's future commutes between Chaldea and Earth would depend on Setsuna each time.

Moreover, he had to wait for the cooldown on his ability. Frequent portal openings to these few worlds reduced his opportunities to explore and pioneer new ones.

Shipgirls at the port would eagerly wait for the portals, which only opened every few months, leaving them frustrated and pitiful to watch.

With the Dimensional Anchor, however, all the worlds they had visited before could truly be connected as one.

"Can it be built?" Setsuna asked, focusing on practicalities.

"Yes, its structure isn't too complex, and the blueprints are very detailed. We have all the required materials, and the Bulins should be able to produce a prototype in a few days, meow," Akashi replied after examining the blueprints carefully.

"That's fantastic. Make a few as quickly as possible, and deploy them in the worlds we've already visited," Setsuna said with excitement. He then handed Akashi the blueprints for the Sundial Array.

This was originally a superweapon from Red Alert 3, part of the Empire of the Rising Sun faction, but the system had provided him with a modified version.

"Take a look at this."

"Meow?! A world wonder?!" Akashi exclaimed in shock, burying herself in the mountainous stack of blueprints to study them closely.

"A defensive superweapon… It consumes a massive amount of energy to activate a 'Ceasefire Field.'"

"When the field is active, all enemy special abilities within range are forcibly nullified, and all high-energy reactions and physical projectiles are blocked…"

"Commander, the description of the Ceasefire Field is quite fitting, meow!" Akashi said, shaking her head in amazement.

In simpler terms, the Sundial Array was an advanced energy generator.

Once activated, it generated a massive shield over a wide area, blocking incoming projectiles—whether missiles or energy cannons.

Within the shield's range, enemies' special abilities would also be nullified.

The stronger the enemy, the more energy it would consume to nullify their abilities.

Energy-based weapons and missiles from the technological side couldn't penetrate the field, and supernatural abilities from the magical side would be rendered ineffective.

It was no wonder the Sundial Array earned the title of "Ceasefire." Once activated, it essentially brought world peace—no one could cause trouble within its range.

"Can it actually be built?" Setsuna asked directly. His instincts told him this was far more complex than the original version.

"Uh…" Akashi dug through the blueprints for a while longer.

"The engineering scale is indeed massive, equivalent to building a small city, but with the specialized Bulins, it should be doable, meow…"

"Additionally, the Sundial Array's core lies in its power supply. The more energy it receives, the greater its range and effectiveness."

"According to the calculations on the blueprints, if enough energy can be supplied, the Ceasefire Field could even cover an entire solar system, meow."

Hiss—

Richelieu, Formidable, and the others observing couldn't help but gasp in surprise.

It truly was a world wonder—protecting an entire planetary system was indeed a prestigious feat.

"Start powering it with a Wisdom Cube, gather the resources and Bulins, and get this wonder built as quickly as possible," Setsuna ordered decisively.

With the Sundial Array, even if they couldn't defeat enemies from other worlds, they would hold a massive advantage in homeland defense.

Moreover, this superweapon synergized perfectly with the Authority of Interdimensional Warfare.

What was the greatest fear after declaring war on another world? A counterattack on home territory.

Once the Ceasefire Field was active, invading enemies would likely struggle to even defeat a Bulin. They could even feign retreat, luring enemies into an ambush.

"Ah, this is truly the era of wonders," Setsuna remarked aloud, feeling a deep sense of satisfaction.

"..."

"If you love wonders so much, why not build yourself a giant pyramid or something?" Gudako asked, utterly baffled by Setsuna's obsession with construction.

"With the combination of my human, machine, and Wisdom Cube integration, I can live until the heat death of the universe. What do I need a pyramid for?"

"Besides, if I build one, wouldn't you be the one lying inside it in the future?" Setsuna replied nonchalantly.

"Ah?! So I'm the one with the shortest lifespan?!"

Gudako's eyes widened in shock as she clung to Setsuna's leg, tears streaming down her face.

"Think of something, please?! You wouldn't leave me to go first, would you?!"

"What if I end up as an old granny or a mummy while you all stay young forever?!"

"..."

Setsuna smacked Gudako lightly on the head twice.

"You're not even twenty yet. What's with the imagination?"

"Later, when we achieve ascension—whether it's through psionics, machines, or genetics—you can pick one. If that doesn't work, study magic properly and save humanity; maybe you can become a Heroic Spirit," he said.

Gudako tilted her head up.

"Can I save humanity using spaceships and Gundams? Those seem way more effective than magic."

"..."

"Do you want to become a machine spirit or something?!"

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