Crossover Shipgirls: Building a Dimensional Empire from Scratch

Whoosh—

In the void of space, the Strelitzia in its Apus Form maintained cruising posture.

This thing literally ran on love.

Setsuna and the shipgirls could all feel it.

Building a starship the size of a battleship wasn’t difficult—but making a 60-meter-tall mecha transform itself into a battleship was a completely different story.

What surprised Setsuna most was that, in its Apus Form, Strelitzia now possessed several components that neither he nor the engineering division recognized.

For example—the massive horn-shaped cannon on its head, and the wing-like armor spread from its back. It was as if they had materialized out of thin air.

”Did we ever have the Bulins manufacture that thing, nya?”

Back on Earth, Akashi and Daedalus were both baffled.

They clearly remembered only giving Strelitzia a standard modernization—upgrading its systems with the Starsea Empire’s cutting-edge tech.

But the weapons appearing in its Apus Form? They’d never even seen them before.

Was it really reasonable for a mecha tens of meters tall to expand into a full-fledged interstellar battleship?!

From the scan data, there wasn’t even any sign of its armor being stretched thin. If anything, its durability had increased to the next tier.

”Materialization out of nowhere?! Isn’t Strelitzia a bit too idealistic?!”

”That’s the power of love~ tsk tsk tsk…”

Observer playfully smacked Purifier with a tentacle while watching Strelitzia’s transformed form with satisfaction.

”Commander, I told you before—Strelitzia has some metaphysical factors built in.”

”According to the original series, as long as the stamen and pistil share a mutual understanding and full synchronization, they can achieve complete compatibility with the FRANXX unit—unleashing its true potential.”

”Mm… though you two haven’t quite reached the ’final stage,’ so it’s still lacking a bit…”

”?”

Setsuna wasn’t sure if Observer was being serious or just teasing him again.

”Is that so?”

The Klaxosaur Princess froze briefly—then suddenly turned around.

Whoosh—

The tendrils and chitinous limbs on her back merged with the Strelitzia, and she lunged forward.

Her pale-blue hands gently cupped Setsuna’s face.

”Like this? …Thank you.”

”I think… I understand you now.”

Though she didn’t speak aloud, their minds were connected in the Apus Form—the Princess’s thoughts directly echoed within Setsuna’s consciousness.

Then, she leaned in.

A soft warmth pressed against his lips.

01 was far bolder than Setsuna had anticipated—or rather, she was simply direct when expressing emotion.

Even after two full minutes, she showed no sign of letting go.

”!!!”

Zzz—

A holographic interface projected beside the cockpit.

It was the live feed from the Siren engineers and repair shipgirls monitoring the test.

”Hey??!”

”We’re supposed to be testing the new equipment here! What kind of livestream do you think this is?! At least turn off the lights first!!”

Observer protested loudly.

”And could you maybe stop clinging to the Commander like that?! Are you filming a soap opera?!”

”Oh.”

Reluctantly, the girl pulled away.

Her silver hair brushed across Setsuna’s face, tickling his skin.

Despite her slightly bluish complexion, paired with breathtaking features and the faintly wrapped black ribbons around her body, she exuded a strange, ethereal beauty.

”I was testing your theory,” she replied coolly to Observer. ”To see if it could really make Strelitzia stronger.”

”?”

”Give you a ladder and you’ll climb the whole building, huh?” Observer muttered, feeling like she’d dug her own grave.

How could someone actually take that seriously?!

”I was just kidding…”

Observer cleared her throat and tapped at the interface, examining the data.

”Commander, to be precise—Strelitzia’s Apus Form actually draws energy from the connection between the stamen and pistil.”

”The more emotional energy the pilots provide, the stronger the mecha becomes—just like when the Klaxosaur Princess shared her power with 02 and one-shot the entire VIRM fleet.

”The amplification rate depends on the compatibility between the stamen and pistil—and the maximum energy they can sustain.”

”For now… it seems your most compatible pistil is 01.”

Setsuna understood her explanation.

He could indeed feel a portion of his own power being drawn into Strelitzia.

The Apus Form’s strength depended on the pilots’ synchronization and individual power levels.

While the Spirit of Origin, Tohru, and others might be stronger than the Klaxosaur Princess, none of them could match 01’s synchronization potential with a FRANXX unit.

So, if he ever needed a co-pilot, she was the best choice.

”What about me?! I’ve been piloting Gundams forever! I’m not weak either!” Gudako protested.

”You…” Observer’s eyes darted around before replying.

”I’ll admit, you’re experienced at piloting Gundams—but you still can’t beat 01, can you?”

”???”

The human girl’s jaw dropped.

”What the hell?! Childhood friend losing to the newcomer?! I was here first!!”

...

Half an hour later—

Clank—

With the experimental tests complete, Strelitzia reverted to its normal form and landed back on Earth.

”Not bad. It’s far stronger than any standard mecha—very impressive,” Setsuna nodded in satisfaction.

It outperformed even the Turn A, and now boasted a dual-pilot combo attack feature.

Even if he didn’t often use mecha combat, it might still be fun to take it out for a spin once in a while.

”Use this design as a base and build another unit for Ritsuka Fujimaru.”

”As for the Genista and Chlorophytum FRANXX units, modernize them according to their unique characteristics.”

”They’ll be for the girls we bring back from the DITF world.”

He issued the order decisively.

”Understood, nya~”

Akashi called over a large team of Colorful Bulins, who immediately started hammering away with clang-clang noises as they began mass production.

The Klaxosaur Princess remained expressionless, as if nothing had happened earlier aboard Strelitzia.

”I’ll join you. I want to study Strelitzia a bit more,” she said softly.

After experiencing the Apus Form, she had developed an unusual interest in the Starsea Empire’s modified FRANXX design.

”Sure thing. Since FRANXX units were originally based on Klaxosaur weapons, we’ve still got plenty of questions for you, nya,” Akashi replied enthusiastically.

”Also, we’ve collected some magma energy samples. We’re planning to isolate and analyze the active components—your help would make it much easier.”

”Don’t worry, we won’t extract it directly. We’ve got more advanced methods now—just need to understand the structure, and we can replicate it ourselves…”

”Alright,” the Klaxosaur Princess nodded slightly.

”Good.”

Setsuna didn’t know what was going through her mind. After sixty million years of solitude, she’d developed an extremely restrained personality—often acting on her own without explanation.

He decided to let her be.

...

Once the Strelitzia modifications were complete, Setsuna refocused on the expedition plan.

Within a few days, most of the expedition team had thoroughly studied the world of KonoSuba.

Everyone was fired up, eager for the Commander to lead them on their next adventure.

”Alright, let’s go—time to abduct a few goddesses!”

...

A few days later—

Outside the capital, the expedition team stood beside Setsuna, fully geared and ready to depart.

The girls chatted lively among themselves, each checking and adjusting her equipment.

Since this expedition targeted a magic-based world, the accompanying members were mainly those from the magical or human side. Most of the shipgirls remained stationed at base, managing interstellar development and logistics.

They would only join Setsuna in person when overwhelming firepower or rapid conquest was required.

”So, a divine-type world, huh… sounds interesting.”

Fu Hua stood next to Setsuna, drawing the Xuanyuan Sword and inspecting it.

”I really hope I can spar with one of their goddesses.”

”???”

”Hey, Immortal—keep it down. Beating up idiots is still a crime,” Setsuna sighed, black lines forming on his face.

Griseo, Mio, and Tohru were also by his side.

Mio and Tohru were Setsuna’s essential trump cards for magic worlds. No matter how peculiar a world’s powers were, nothing could compare to the raw might of the Spirit of Origin or a dragon who could punch mountains apart.

Griseo, as always, quietly clung to the corner of Setsuna’s coat, carrying her sketchboard on her back.

”Commander, what color… is the world of swords and magic?” the little girl asked softly, her voice airy and serene.

She wouldn’t be joining any battles or conquests—she usually spent her time in other worlds quietly painting.

Setsuna didn’t mind. Having an adorable loli around wasn’t a bad thing—it gave him someone to pat on the head, tease for fun, and increase affection points with.

Whoosh—

He opened the Hyperdimensional Star Map and selected their destination.

[KonoSuba: God’s Blessing on This Wonderful World (Class III Magic World)]

This world possessed multiple sub-realms, including pre-space-age human societies, high-magic planes, and divine realms governed by gods of varying authority.

These worlds were interconnected through the divine realm, controlled by beings with godlike power.

[Comparison of Strengths:]

Technological Level: Like an Ant.

Military Strength: Slightly Inferior.

Economic Power: Like an Ant.

...

”Eh?”

Setsuna blinked, surprised.

He hadn’t expected KonoSuba’s divine realm to be rated as only ”slightly inferior.”

So despite its many gods, the system still ranked below the Starsea Empire.

He guessed most of those so-called gods had intimidating titles but weren’t actually strong in combat—Aqua and Eris certainly came to mind.

They were nowhere near the level of truly omniscient and omnipotent beings who could reshape cosmic law with a thought.

As for technology and economy…

No matter how many magic worlds existed, none could match an interstellar civilization’s industrial output.

The productivity gap was astronomical.

”By the way,” Setsuna mused, ”for a world connected to multiple dimensions, where exactly will the gate drop us?”

After a moment’s thought, he decided it didn’t matter—with his power, wherever they ended up would be fine.

He simply raised his hand.

”Whatever. Let’s just head over and find out.”

Hum—

[Dimensional Gate Established]

[Constantinople → KonoSuba: God’s Blessing on This Wonderful World]

As space twisted, a rainbow vortex opened before them.

”I’ll go first, Commander~!”

Tohru cheerfully hopped into the portal, followed by Setsuna and the others.

...

KonoSuba World—

A vast, empty expanse.

There were no furnishings or boundaries—the very laws of space seemed detached from the outside universe.

Everything stretched infinitely, painted in pure, seamless color.

A girl with long, sky-blue hair sat lazily on an ornate chair, idly munching on snacks from the table.

Her sleeveless dress and thigh-high boots accentuated her flawless figure, and the translucent beads in her braid glimmered faintly as they caught the light.

Her eyes were the same ocean-blue, her beauty ethereal and divine. The feathered cloak draped faintly behind her radiated faint traces of godhood.

In this vast, featureless realm, there was only her—the blue-haired goddess—and her table and chair.

”Ugh… I’m so bored.”

Aqua stuffed another snack into her mouth and chewed absentmindedly.

”Hmm, do I have any more high schoolers waiting for reincarnation? Can I get a strong one this time? That world’s difficulty is way too high…”

As the goddess in charge of handling reincarnations for Japan, Aqua was feeling quite bored.

After all, the worlds she managed were tough enough that most candidates backed out the moment they heard the details—even with cheats or divine blessings, few were willing to go.

She often had to resort to a little trickery just to convince people to go at all.

”Eh? Divine energy reaction? Someone’s arriving again?”

Aqua suddenly sensed a strange power.

Normally, when someone from her jurisdiction died, their soul would automatically be transferred to her.

But this time, the spatial fluctuation wasn’t from the familiar divine network.

”Wait, could it be a demon?! Who would dare invade here?!”

Before she could react—

BOOM—

A portal tore open in midair above her chamber, swirling with prismatic light.

Thud—

A dragon girl with horns and a long tail dropped through first.

Tohru looked around curiously.

”Who are you?”

”Eh? Are you Japanese too?” Aqua blinked in confusion, feeling an odd sense of danger from the newcomer.

Moments later, a silver-haired, blue-eyed elf, a blue twin-tailed loli, Fu Hua, and finally Setsuna all descended through the gate.

”???”

”So many souls at once? And all within reincarnation range?”

Aqua was baffled.

”Did you all die in a plane crash? Wait—one guy and four girls… don’t tell me—”

”Hold on, I don’t recall seeing your names in the registry! How exactly did you die?”

Normally, every soul she received came with full life records. But the people before her were complete blanks—untraceable.

”...Damn it, Aqua?!”

Setsuna facepalmed, looking entirely unsurprised.

Of course—it had to be her. Straight to the heavens, no detours.

No wonder she was considered the protagonist of KonoSuba.

”You know me? Wait, forget that—who are you people? How did you end up in my room?!” Aqua demanded, scanning them carefully.

They all looked young, and by her logic, that usually meant accidental death cases.

Setsuna… probably just another ”ordinary” high schooler from Japan—one of those who routinely got trucked into other worlds.

He just looked a bit too mature for that.

Fu Hua and Mio seemed about the same age. Aqua wasn’t used to processing this many girls at once.

As for the dragon girl… she didn’t even know what to make of her.

Finally, her gaze landed on little Griseo.

”Such a young child too…”

Instinctively, Aqua felt a pang of pity.

She gently patted Griseo’s head.

”Poor thing. I don’t have the power to revive you directly back in Japan, otherwise I’d send you home right now.”

”How about this—since I’m a kind goddess, I’ll give you a strong cheat ability! Or maybe wait a bit, and I’ll find you a powerful companion, okay?”

”???”

Griseo tilted her head, confused.

She had no idea why this woman was pitying her out of nowhere.

”I’m not going anywhere. I’m staying with big brother Setsuna,” she said softly, tugging at his sleeve.

She could sense something strange about Aqua.

”Big brother… her color feels strange…”

”Hm? Isn’t the color of stupidity blue?” Setsuna said flatly.

”No, it’s more like… being near her makes my thoughts and reactions slower…”

Griseo’s words were innocent, but sharp.

”Oh, then yeah—that’s definitely stupidity. Makes sense,” Setsuna nodded.

”Stay away from her, or it might be contagious,” Tohru added seriously.

Griseo was easily influenced by the ”colors” of those around her—if she stayed too close, her mannerisms and thinking might begin to mirror theirs.

”???”

Aqua glared furiously.

”Who are you calling stupid?! That’s blasphemy against a goddess!”

—

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