Crossover Shipgirls: Building a Dimensional Empire from Scratch

The moment Setsuna spoke, not only Akashi and Purifier were stunned, but even Richelieu and Taihou were momentarily dumbfounded.

”Commander, it’s okay. As long as Taihou is with you, Taihou will destroy every enemy standing in your way.”

”From now on, just take Taihou along on every mission~~,” the possessive shipgirl immediately declared.

”No, I have to figure out a solution. Whether it’s through technology or magic, I need to at least keep up with you all,” Setsuna decisively rejected the suggestion of relying solely on her.

”In that case, it seems the Commander’s strength is really being held back by the Strike Freedom unit...”

Richelieu rested her chin on her hand thoughtfully.

The shipgirls, who had evolved from conventional naval vessels to starships, had seen their combat strength elevated to an entirely new level. With every advancement in material science, engineering, or physics, they could be outfitted with new weapons and ship systems.

In comparison, under the same technological conditions, a Gundam was outclassed by a starship in terms of both firepower projection and durability.

The Strike Freedom was developed quickly to boost Setsuna’s capabilities as soon as the first tech tree was unlocked. Now, it was struggling to keep up with the main fleet’s rapid development.

”Uh...”

Akashi and Purifier sat in the office, scratching their heads as they pondered the issue.

They even invited a few more Sirens and Heroic Spirits to join in brainstorming a solution.

”I have a relatively straightforward idea, meow,” Akashi spoke first.

”Just continue upgrading the Commander’s unit, equipping it with more advanced weapons and systems.”

”If we can acquire stronger materials or technology, we could directly enhance the Strike Freedom’s armament system, Phase Shift Armor, and structural components.”

”In the tech tree the Commander gave us, there’s even a design for an advanced Turn A Gundam with the Moonlight Butterfly system,” Akashi said as she pulled out some documents and laid out a blueprint of a blue-and-white Gundam.

The most striking feature was the pair of multicolored, butterfly-like wings extending from its back.

”The Moonlight Butterfly system can release massive amounts of self-replicating nanomachines that disassemble all materials they come into contact with down to the molecular level.”

”Then, the disassembled material is replicated into more nanomachines, continuing the destruction process. This chain reaction can potentially annihilate an entire planet.”

”It’s just that building it is a bit of a hassle. It took me forever to understand its blueprint, meow,” said Akashi, twitching her beast-like ears.

For Akashi, learning about the Gundam series’ technology was akin to starting from scratch and studying another world’s entire scientific and technological system, from fundamental theories to modern applications. Coupled with her responsibilities managing their base and various research projects, it had taken her almost a year to fully grasp how to construct this ultimate weapon.

”Isn’t this just a nano-plague... Hmm, it sounds suspiciously like the planet-destroying weapons of the Omnics.”

Setsuna felt an odd familiarity with the chain-reaction devastation caused by the nanobots.

”What about the Turn A’s other aspects?”

”Its speed and conventional weapons are better than the Strike Freedom’s, but it’s still just over 20 meters tall. It can’t accommodate main cannons of too large a caliber,” Akashi replied.

”...”

A Gundam with planet-destroying capabilities was undoubtedly appealing. However, it still seemed limited in conventional combat, unable to break out of the mech’s inherent framework.

Setsuna turned to Purifier, curious about what insights the Siren might offer.

”Hmm...”

Purifier lounged on the sofa, crossing her legs lazily, her usual smug expression intact. After a moment of thought, she spoke nonchalantly:

”If you want to keep up with the starship-grade shipgirls, why don’t you just turn into a starship yourself?”

”With how efficiently you use the Wisdom Cube, forget about being a cruiser—you could be an aircraft carrier or even a battleship. Heck, you could become a sea or airborne fortress!”

”I would if I could, but I’m already bound to the Gundam,” Setsuna replied, spreading his hands helplessly.

The Wisdom Cube could materialize humanity’s collective perception of a particular object. If it were possible, he would gladly unbind from the Strike Freedom and bind to the Eternal Snowfall.

But that simply wasn’t how it worked—this wasn’t a password lock he could reset.

”Why not just put another Wisdom Cube into your body?”

”If you had two cubes, you could use both the Gundam form and transform into a starship. Wouldn’t that make you invincible?”

Purifier’s matter-of-fact suggestion left everyone stunned.

The sheer audacity of the idea floored them, rendering the room speechless for a moment.

”Two Wisdom Cubes in one body? Are you serious? How would that even work?!”

Akashi’s eyes widened as she swiveled her upright ears toward Purifier.

”Ordinary people can’t handle it, but I think the Commander can,” Purifier said as she stood up and gave Setsuna a once-over.

”We’ve previously researched the technology of installing multiple cores in a single ship. Since the Commander’s physical capabilities are absurdly strong, adding another core shouldn’t be difficult.”

”The Compiler should be able to do it.”

The little girl in the white dress beside her nodded.

”Indeed. Zero mentioned before that you’re special and capable of integrating various kinds of power.”

”Zero? Who’s that? Observer Zero? Where is she?” Setsuna was about to press for more details, but Compiler showed no intention of elaborating. Instead, he shifted to another question.

”Then... can I install more than two?”

The power of one Wisdom Cube was already overwhelming. If he could run a setup with ten or eight cores, wouldn’t he be unstoppable?

”Based on your current physical capacity, you can only support a maximum of two cubes simultaneously,” Compiler replied, her face expressionless.

”Are there risks? You’re not secretly plotting something, are you?” Richelieu’s gaze landed on Purifier, her expression full of suspicion.

”Please, we’re all in the same boat now!” Purifier spread her hands in mock protest. ”I’m counting on you to turn me into a starship someday and take us to the stars. If something happened to the Commander, wouldn’t you all hunt me down and kill me in the docks?”

”...Fair point,” Richelieu conceded, turning to Setsuna. ”Commander, what’s your decision?”

”...”

Option A was to upgrade the Strike Freedom into the Moonlight Butterfly model.

Option B was letting the Sirens modify his body to integrate dual Wisdom Cubes, allowing him to possess two transformation forms simultaneously.

After a moment of consideration, Setsuna made up his mind.

”I want both.”

”Akashi, bring Bulin to build the new Gundam. Compiler, Purifier, prepare for the modifications.”

...

A few days later.

At the Siren naval port, surrounded by several shipgirls and senior Sirens, Setsuna lay on a bed being wheeled into a room that resembled an operating theater.

The interior was designed in the Sirens’ signature cold black-and-yellow aesthetic, exuding an oppressive atmosphere.

Of course, despite being called surgery, there was no actual need for cutting or invasive procedures.

Compiler manifested her enormous jellyfish-like rigging and gently brushed it across Setsuna’s face.

”I will convert the Wisdom Cube’s energy and inject it into your body using micro-layered compounds,” Compiler explained, her ethereal voice devoid of emotion.

”The modification process will take several days. The Siren’s energy may create minor repulsion with your existing energy, leading to possible hallucinations. Please do not be alarmed.”

”Let’s begin,” Setsuna said, closing his eyes.

He placed his trust in the Magic pathways and the Sirens’ idealism-based technology, especially considering that this little girl, according to the original storyline, was responsible for researching and creating Mirror Seas. Possessing some unimaginable abilities seemed par for the course.

Outside the room, several shipgirls and Heroic Spirits stood on tiptoe, watching the Compiler’s modification process intently.

”If anything happens to the Commander, I’ll destroy this port and all of them...” Taihou murmured, biting her lip as she leaned forward.

”That’s unnecessary. I don’t think they mean any harm,” Enterprise replied, shaking her head. ”Besides, it’s a good chance to learn more about Siren technology.”

The modification process wasn’t overly complicated and was overseen by Compiler, Purifier, and several other Sirens.

From Compiler’s jellyfish-like massive rigging emerged a variety of mechanical arm-like devices. After dissolving the Wisdom Cube, the compound was mixed with a mist and injected into Setsuna’s body.

...

Unconsciousness enveloped him.

In the void, Setsuna’s mind was flooded with a torrent of strange, fragmented images.

A white-haired little girl clutching a stuffed animal, sitting within a glowing blue jellyfish-like rigging.

Sirens with bizarrely designed riggings and corrupted versions of shipgirls.

The chaotic flood of Siren information swirled in his mind like shattered shards of imagery before he eventually drifted into a deep sleep.

...

”Ugh...”

”Cough, cough...”

He didn’t know how much time had passed.

His consciousness slowly returned to his body. As his eyes fluttered open, his vision was filled with the sight of a fair-skinned Siren girl with yellow eyes and white hair tied into a long ponytail.

Purifier, full of energy.

”You’re awake?!” she exclaimed brightly.

”Commander, the operation was a great success. Congratulations—you’re now an adorable little shipgirl~!”

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