Crossover Shipgirls: Building a Dimensional Empire from Scratch

Outer Earth Orbit.

The Eternal Snowfall, along with the newly upgraded space fleet, cruised through the vastness of space.

The shipgirls, eager to test their newly acquired weapons and systems, began their warm-ups in zero gravity.

With the enhancements provided by the Wisdom Cube, the Fleet of Fog’s weapons had become far too destructive for testing on Earth.

If they used too little power, they wouldn’t get a real sense of the capabilities. But if they unleashed full output…

Well, Earth was still their home, and leveling the surface wasn’t exactly ideal—especially considering Bulins and Manjuus were still actively mining resources there.

Thus, their new test subjects became the various asteroids and celestial bodies surrounding Earth.

—Hummm—BOOM!!!—

A dazzling array of super-graviton cannon fire streaked across the space, resembling an extravagant light show.

Compared to the Positron Blaster Cannons, the Super-Graviton Cannons possessed far superior firepower and range—by several magnitudes.

Click—

Nagato activated her main cannon, locking onto a target near the Moon.

BOOOOM——

After fully charging, a crimson energy torrent surged forth, sweeping through the asteroid belt in its path, obliterating everything before striking the Moon’s surface.

A massive impact crater—over 300 kilometers in diameter and nearly a thousand kilometers deep—was gouged into the lunar plains.

”Unbelievable… I have never witnessed such destructive firepower before.”

Nagato twitched her fox ears, clearly satisfied with her new weaponry.

Other shipgirls, eager to test their defensive capabilities, started firing at one another for stress testing.

ZZZZT—

Musashi unleashed a full-powered barrage against Shinano, activating both main and auxiliary cannons.

The resulting storm of high-energy projectiles was so blinding that the gathered Spirits and Heroic Spirits nearly had to shield their eyes.

Musashi’s firepower alone could wipe out any nation on Earth in under five minutes.

Yet, the target of this onslaught—an aerospace carrier—remained unscathed, comfortably shielded behind a shimmering blue barrier.

Super-Graviton Cannon striking the shield created a breathtaking display of refracted energy, resembling fireworks dancing across the void.

”Musashi, you’ll need to try harder~ My Klein Field is only at 36% capacity. We’ve got a long way to go before it even begins to overload…”

A silver-haired fox girl sat within her command bridge, leisurely monitoring her ship’s status.

Even under sustained bombardment from a Yamato-class battleship, her Klein Field maintained over half its energy reserves.

Stronger computational power meant a stronger Klein Field.

By default, aircraft carriers and battleships had far superior defensive capabilities compared to smaller cruisers and destroyers.

”Tch… If we don’t use specialized countermeasures, breaking through the Klein Field with standard weaponry is next to impossible.”

Inside Musashi’s bridge, another purple-haired fox girl sighed.

Unfortunately, while testing, Corrosive Warhead Torpedoes were off-limits.

For one, they were incredibly expensive to produce.

And more importantly, they inflicted true damage—if they landed, the target would require extensive repairs, creating unnecessary trouble.

Meanwhile, Taihou had deployed hundreds of space fighters, each armed with miniaturized Super-Graviton Cannons and corrosion-based weaponry.

She herself fired her Super-Graviton Cannon, the crimson beam searing across the lunar surface, carving deep trenches into the Moon.

One key difference between Super-Graviton Cannons and Positron Blaster Cannonss was that Super-Graviton Cannons could sustain their fire for long durations—like massive industrial-grade laser cutters.

Using this function, Taihou started carving shapes into the Moon’s surface with her weapons and fighter squadron.

...

At the same time, down on Earth, ordinary civilians like Kanae, Seitenshi, and Kisara Tendo, who were stargazing, were greeted by an unexpected and somewhat unsettling sight:

High above them, the bright white Moon had begun changing.

As they watched in awe, it seemed as if someone was using a massive red calligraphy brush to deliberately outline a giant heart shape across the lunar surface.

From hundreds of thousands of kilometers away, they couldn’t see Taihou’s ship, but they could see the Super-Graviton Cannon etching patterns onto the Moon’s surface.

A massive heart shape was now carved into the lunar landscape.

”???”

”Is this some kind of insanely extravagant love confession?!”

The native inhabitants from Demon Slayer and Black Bullet universes, now mingling together, stared at the sky with dumbfounded expressions.

”Makkiya bakku ne…”

Kanae, eyes sparkling, watched in awe.

In the Grand Library, Lucoa yawned, lazily glancing up at the celestial display—only to freeze in place.

”Eh? What’s Setsuna up to this time?”

”Is he confessing his love to someone in the city?…”

The dragon woman was thoroughly puzzled.

”This is my love for Commander!!!”

Taihou’s seductive voice echoed through the fleet’s communication network.

”As long as Commander looks up at night, he’ll always see my love~~”

”...”

”We’re planning to colonize the Moon one day! Stop defacing it with random messages!!”

”And Nagato, you too! Stop using the Moon as your personal weapons testing ground!!”

Richelieu’s eye twitched. She desperately wanted to teleport onto Taihou’s bridge and knock some sense into her.

Taihou promptly activated her Klein Field and ignited her thrusters—blasting off toward Mars.

”I’ll carve my love for Commander onto Mars next—”

”You stop right there!!! Taihou!! I’m opening fire!!”

”...”

”Your shipgirls have completely lost it.”

Aboard the Eternal Snowfall, Gudako and the gathered Heroic Spirits and Spirits watched the spectacle unfold from the observation deck.

They felt like outsiders, unable to comprehend why the shipgirls were acting like excitable children over a simple equipment upgrade.

—Though, to be fair, many destroyer-class shipgirls were actual children.

”Every shipgirl carries a dream of exploring the stars,” Setsuna chuckled. ”Each upgrade brings them one step closer to that dream.”

”Wish we could get stronger just by upgrading our gear,” Kurumi sighed.

She had witnessed the shipgirls’ second-generation hulls firsthand. Now, seeing their third-generation forms, the difference in strength was undeniable.

”Yeah… I thought I was pretty strong. But now? Tch…”

Jeanne Alter clicked her tongue.

Her remark struck a chord with the Heroic Spirits and Spirits.

On Earth, they were powerhouses, standing far above mere mortals.

But in space? Watching the shipgirls continuously upgrade their weapons, rapidly increasing their combat potential… Envy was an understatement.

Artoria and both Jeannes had seen the original Azur Lane shipgirls in action.

At first, their firepower was roughly on par with Anti-Army or Anti-Fortress Noble Phantasms. Things like artillery bombardments and aerial strikes weren’t that overwhelming.

But after two major upgrades?

Now, every shipgirl could effortlessly raze entire nations or glass planetary surfaces in minutes.

Meanwhile, the Heroic Spirits and Spirits hadn’t changed.

The difference was even more apparent in space. Here, compared to starships, they felt utterly insignificant.

”…Maybe it’s because we’ve been focusing on advancing the technology side?”

Setsuna pondered aloud.

”It’s relatively easy for the shipgirls to grow stronger—just keep advancing technology and upgrading their equipment. But you Spirits, Heroic Spirits, and dragons… you’re a bit more complicated.”

Setsuna swept his gaze across the group.

Technology was important, but so was magic.

As the ruler of a Interdimensional empire, it was unacceptable to neglect one side.

”I’ll arrange for a dedicated magic research division in the future, one that focuses on developing magical technologies. Maybe we’ll find ways to enhance your strength.”

”For example, we could study the Root or the Inverted Tree… though that will take time, since your power systems are completely different from one another.”

He mentally added another item to his ever-growing to-do list.

”Thank you, husband,” Kurumi replied softly, gently massaging his shoulders. ”I would love to be useful in battle.”

She firmly believed that anything Setsuna promised would eventually come true.

”But, Commander, shouldn’t you test your new equipment?” Yamato suddenly asked.

The Fleet of Fog shipgirls had yet to undergo their starship upgrades, so they remained on the Eternal Snowfall for now.

”Me?”

Setsuna pondered for a moment.

Looking outside, he saw that the shipgirls were completely engrossed in their training—testing shields, measuring range and firepower, and even a few mischievous destroyers engaging in Super-Graviton Cannon duels.

”Hmm… we’ll still need the Moon later, so let’s use Mars. The range should be sufficient.”

With that, he adjusted the ship’s targeting system, locking onto the distant, rust-colored planet.

Bzzz…

The spinal-mounted main cannon charged up.

BOOOOOM—

A dark crimson particle stream tore through the void, streaking toward its target.

The shipgirls, who had been playing around, paused and turned their heads—only to freeze in shock.

The Eternal Snowfall’s Super-Graviton Cannon was larger than some of their entire ships.

The torrent of energy traversed the 55-million-kilometer Earth-Mars distance at lightspeed.

Boom—

Three minutes later, the attack struck Mars, carving out a crater several thousand kilometers wide and deep.

The impact exposed the planet’s deep crust, causing magma to bubble up and spread across the terrain.

Even without high-precision observation tools, the drastic reshaping of the Martian landscape was apparent.

”That… that blast radius… Isn’t that bigger than all of North America?” one of the shipgirls muttered in disbelief.

”This power level… it’s starting to resemble the data we have on META shipgirls,” Observer whispered to Purifier.

”If the restrictions were lifted in the future, wouldn’t that mean—?”

Bang!

Richelieu narrowed her eyes and slammed her hand on the control panel.

”Commander, I understand that you now have the power to annihilate nations or even entire planets with a single strike… but could you please restrain yourself?”

”We still need the Moon in the future. And we definitely need Mars!!!”

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