Crossover Shipgirls: Building a Dimensional Empire from Scratch

”Mm...”

”Uh...”

Inside the Golden Hind’s hull—

A purple-haired girl slowly opened her eyes. She found herself lying in a large, ornate bed, the decor of the room reminiscent of 16th-century Europe.

Around her stood several unfamiliar people—among them, the silver-haired spirit who had obliterated the Demon Pillar in one strike, a ponytailed orange-haired girl, and a man in a black-and-red military uniform.

”This is...”

Medea Lily shook her head, trying to sit up—

When suddenly, a tentacle appeared in her view, offering her a glass of water.

”Hya?!” Lily let out a startled cry, jumping back.

”You’re awake?” Setsuna greeted her with a smile. ”Welcome to the Starsea Empire.”

”I...” Medea Lily checked herself—her magical energy was full to the brim. By all rights, she should have disappeared after the Demon Pillar was destroyed.

”The Commander filled you up,” Gudako said matter-of-factly.

”Eh?” Lily was even more shocked. Sensing carefully, she realized the vast power sustaining her was faintly connected to Setsuna. He had poured a huge amount of mana into her to maintain her existence—though Gudako’s wording made it sound... odd.

”We weren’t just—”

”I know your story,” Setsuna cut in, patting her shoulder. ”You were defeated by a mage, bound by a forced oath, and silenced, right? In this world, you wanted revenge—tricking Jason into believing that sacrificing a god to the Ark would grant invincible power. But in reality, doing that would destroy this already unstable world, correct?”

The girl’s eyes widened—she couldn’t understand how he knew so much.

Sacrifice a god to gain invincibility? Sure—but if the world is destroyed and no one’s left, you’re ’invincible’ by default.

That had been her plan: a trap for Jason. But Setsuna had disrupted everything. Still, the outcome wasn’t so different.

”Want to join us? I can be your Master. As for the one who defeated you before—funny thing, we’ll be fighting him eventually~”

”Eh?” Lily blinked. ”Someone like me? I’m not very strong, and I was under someone’s control...”

”No problem—Mio just removed that for you.” Setsuna ruffled her hair.

Medea checked and indeed found the binding magic gone.

”Impossible! He’s a far stronger mage than me—how did you—?!”

”Domain manipulation. Pretty neat, huh?”

”...” Lily glanced between Setsuna and the Spirit of Origin. As a ’betrayer witch,’ she’d never expected a good end. Yet meeting this strange man from another world kept overturning her expectations.

Now she was curious—who exactly was Setsuna? What was this Starsea Empire? And could there truly be a utopia of peace like he described?

”I’ll try it,” Lily decided, convincing herself to take a different path.

She hopped out of bed, adjusted her translucent silk robe, gripped her staff in both hands, and bowed to Setsuna.

”Servant, Caster, Medea. Please take care of me!”

...

After a few days in the Singularity—finishing up loose ends and doing some sightseeing—

On a bright afternoon—

Shwoop—

[Passage Constructed: Third Singularity – Sealed Ends of the Four Seas → Chaldea]

The group stepped through the time-space passage, emerging before Chaldeas.

By projecting themselves into the past through Spiritron Transfer, then using the authority of the time-space passage to return, they could bring back any companions they wished from any era or world.

”More new people?!” Roman exclaimed, eyeing the Heroic Spirits behind Setsuna. Every time he cleared a Singularity, Setsuna never came back empty-handed—he always managed to ’acquire’ more Heroic Spirits.

To be precise, female Heroic Spirits.

If he cleared a few more Singularities, Roman suspected Setsuna might abduct every female Servant in the entire Type-Moon universe.

Perhaps this was the price of saving humanity?

”The Third Singularity has been successfully resolved. We’ll locate the Fourth as soon as possible—it shouldn’t take long,” Da Vinci said gratefully, her eyes lingering on Mio and the Golden Hind. ”You’ve certainly recruited some unbelievably strong companions since last time…”

Given their performance, she mused, ”With your current strength, I doubt any other Singularity could threaten you. Even gods from myth shouldn’t be a problem, right?”

Roman and Da Vinci both came to the same conclusion—based on Setsuna’s group’s display of power, they could probably steamroll the rest of the Singularities blindfolded.

”Mhm.” Setsuna nodded. In the original timeline, Gudako could clear Singularities alone; with his entire army and multi-world elites, it was trivial. If Chaldea could locate them fast enough, restoring human order was within reach.

If he was too busy or lazy to go himself, he could just send Gudako with an escort to bring the Heroic Spirits back.

”Come to think of it… Last time in the Roman Empire, you fought in a Gundam. This time, you didn’t even lift a hand?” Da Vinci asked, looking almost disappointed.

”My ship’s under refit,” Setsuna coughed. ”The Eternal Snowfall is built for efficiently wiping out aliens—it’s not exactly optimized for Singularities.”

...

Back in the capital via the teleport anchor—

They were met by a crowd of curious Heroic Spirits. Chaldea’s Servants hadn’t had new companions in a while, and they eagerly surrounded the newcomers.

”Euryale?!” Stheno immediately recognized her sister. The two met at last—too emotional to speak at first, simply staring at each other.

The Gorgon sisters were now two out of three… and with Medusa likely to show up in duplicate someday, three sisters becoming four was basically a given.

The center of attention, however, was Medea Lily.

”You mean she’s the child form of the witch Medea—like the difference between a full shipgirl and a little shipgirl?!” The Heroic Spirits, having never met the adult Caster, found Lily impossibly cute, unable to connect her to the infamous ’betrayer witch.’

”Mm… The existence of a Servant is… complicated,” Medea Lily explained seriously. ”There is the me who trained only in the temple, and the me who left the temple to sail the seas. Perhaps one day I’ll meet another me.”

Lily-form Heroic Spirits were essentially pure versions—like a Saber Lily without the hardship and betrayal, or a Caster without the witch’s stigma. They were usually young, pure-hearted, and often lolis or teenage girls.

”…One Servant with two, no—multiple forms…” Setsuna felt like Lily had opened a whole new world to him.

”Now I want Saber Lily and Jeanne d’Arc Lily… tch.”

”Oi, Purifier, Observer, can you help me make a little Heroic Spirit?” he called.

”???” The Siren girl was stunned. ”We’re a Siren research facility, not a maternity ward! That’s your business with the Heroic Spirit, not ours!”

...

The capital and Chaldea’s outpost bustled for a short while—showing the new Heroic Spirits around and letting everyone mingle.

After clearing the Horse Girls’ world and the Third Singularity back-to-back, Setsuna’s life returned to its routine while waiting for the Eternal Snowfall’s refit to finish.

At the Starbase, millions of specially modified Bulins worked day and night to build the massive warship, comparable in size to a small asteroid.

First came the keel and framework, then the nanometal alloy plating over the entire vessel. The interstellar armor combined Fleet of Fog nanotech with high-strength alloys provided by Grey.

The dark gray hull took shape piece by piece. Resources tribute from over a dozen vassal worlds were poured entirely into constructing this Juggernaut-class starship.

Normally, only civilizations spanning thousands of light-years could build such giants, but the Starsea Empire managed it by extracting resources from its vassals to the limit.

The Juggernaut’s length and width were nearly a hundred times that of standard starships, with an even more exaggerated overall volume.

Usually, a few hundred Bulins could ”handcraft” a starship in under twenty days. This time, it took a million Bulins a full three months just to complete the outer armor.

With wings extended, the warship was fixed into a dock at the Starbase, its beam exceeding even the base’s own width.

Next came the internal structures and weapons systems. Grey, Sirens, Akashi, and Daedalus all joined the Bulins to design the Fallen Star Lance and finalize construction plans. The base’s top scientists were working overtime.

Meanwhile, on Earth, Setsuna’s life became simple and… monotonous.

Since the remaining worlds would wait until the refit was done, he stayed put.

Flirting with shipgirls, flirting with Heroic Spirits, flirting with dragon girls, flirting with Spirits—everyone together in an endless round of flirting.

With no expedition plans, life slowed down. He didn’t have to plan otherworld strategies; the Angeloids and other shipgirls handled work.

He had plenty of time with the girls.

Or rather, plenty of time to be targeted by them.

”Commander, you’ve received 28 date invitations today: 19 from shipgirls, 3 from Heroic Spirits, and…” Richelieu, in the administrative center, slid the holo-display to him. As his secretary ship, she handled all matters—including his time and harem management.

”Essex invites you to survey the Kepler-30 system…”

”Glorious and Formidable invite you to the Royal Navy’s afternoon tea…”

”Akagi invites you to her hull tonight; Roon made the same offer—please think carefully.”

”Kancolle Yamato wants you to accompany her to Europa; she claims she’s still unfamiliar with starship controls…”

”Artoria invites you to dinner at an Eastern shipgirl buffet…”

”Anchorage wants you to help her with lessons—apparently on imported storybooks from another world…”

The variety made Setsuna’s head spin. Normally, when he was busy, the girls wouldn’t interrupt often. But now that he was free, they all saw an opportunity and launched their own ”seduce the Commander” campaigns.

There were so many, he had to ask Richelieu to handle them for now.

”I miss the Eternal Snowfall,” Setsuna muttered, rubbing his forehead.

Without time-distortion skills, this was awkward—there was simply no way to fit them all in.

In the past, he’d just bring everyone onto the starship and start a time-warp field running at dozens of times normal speed.

With no time distortion, he could only schedule everything like a shift roster—carefully planning each day. Not only did he have to date the new shipgirls, but also take care of the rest of his harem. It was both a technical and physical job.

”Eh? The Master is this popular?” Medea Lily, still new, didn’t understand. She leaned over to look at the holographic list of invitations.

”Isn’t there one inviting the Commander to another star system for exploration? That sounds like work, right?”

”Not a chance,” Richelieu said, pulling up the starmap and marking the system mentioned in Essex’s invitation.

”Kepler-30 is about 1,000 light-years from the Solar System. Considering the Commander’s ship is in refit, he’d have to ride in hers. The hyperspace route requires multiple jumps, and with survey time, it’d be at least three months round trip. Just the two of them, alone in deep space for three months?” She smirked. ”Didn’t think that Eagle Union shipgirl had such sly intentions…”

”And some shipgirls—how come they can crush opponents in exercises, but suddenly ’forget’ how to pilot a ship when the Commander’s around?!”

”...Oh damn,” Gudako muttered, feeling like she was watching palace intrigue, with Richelieu as the empress.

”I don’t mind the Commander dating other sisters, but let’s not get excessive!” Richelieu laughed in exasperation. ”If she takes him away for months, what happens to everyone left at the base?”

”True!” other shipgirls agreed, joining in to scold Essex. Everyone wanted the Commander—hogging him was unacceptable.

”So, Commander, how will you arrange your schedule? If you’re busy, I can politely decline on your behalf—everyone will understand,” Belfast said, stepping forward. She opened the interface, displaying dozens of invitations in neat columns—a rather imposing sight.

”...” Setsuna felt like an ancient emperor choosing concubines from name plaques.

”Commander, who will you pick?” Chen Hai’s wine-red eyes gleamed with curiosity—she wanted to know which lucky girl would win his favor.

”Pick, huh…” Setsuna thought for a moment, then raised an eyebrow. ”Why should I choose just one? Have you ever seen the Commander with only one shipgirl?”

”???”

”Come on—let’s all deepen our bonds together.”

—

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