Crossover Shipgirls: Building a Dimensional Empire from Scratch

Following Setsuna’s orders, the native girls from the Re:Zero world were soon settled in the capital.

”From now on, this will be your station.”

In one corner of the capital, Kanae led Emilia, Crusch, and the others to a beautifully arranged cluster of buildings.

Each action squad’s residence was located here. Initially, there had only been a few—like the Demon Slayer Corps, Chaldea’s Heroic Spirits, and Night Raid.

Even though the number of residents had grown significantly, the area still felt vast and empty, leaving ample room for every new arrival.

”Wow...”

Emilia, unfamiliar with everything in the Starsea Empire, was a bit nervous at first. But seeing that the capital was filled with kind and friendly girls like Kanae, she relaxed slightly.

Following them, she entered what would be her new home.

It was still the Empire’s standard detached villa design—simple inside, yet brimming with a sense of futuristic technology.

The furnishings and decorations were things the native girls had never seen before.

”We can really live here?”

Anastasia, Crusch, Priscilla, and the others stared wide-eyed in disbelief.

There was no need to mention the little girls who had lived in slums before—but even Crusch, a noble’s daughter, couldn’t help but feel that compared to the Starsea Empire, her residence in the Re:Zero world had been no better than a kennel.

”Of course. This is standard welfare for companions who join the Starsea Empire.”

Beep—

Kanae casually opened a holographic interface and briefly explained the rules to the group.

”If you need anything, you can visit the commercial district to choose what you like, or have an Angeloid deliver it to you. There’s no currency here—everyone takes what they need, but waste is forbidden.”

”As for laws and regulations, you can read the provided materials. Private duels are strictly prohibited within the capital. If you wish to spar, go to the training arena.”

”Later, the Life Sciences Department will conduct a basic physical examination for you and schedule your genetic enhancement. If necessary, you can also apply for an advanced transformation surgery.”

For newly recruited girls, the Starsea Empire’s standard welfare included food, housing, and equipment distribution.

Combat personnel were also entitled to genetic ascension and hyper-mutation surgery.

Even those previously powerless would experience an explosive rise in strength after genetic fortification and fusion with a Honkai Beast.

With proper equipment and a bit of training, they could become a formidable combat force.

”Oh...”

The newly arrived native girls listened in a daze, overwhelmed by the Empire’s generosity.

The Starsea Empire’s newcomer package was almost unbelievable.

”Th-thank you...”

”If there’s anything I can help with in the future, I’ll do my best...”

Emilia quickly expressed her gratitude. Though she barely knew these people, she felt unworthy of receiving such kindness.

”It’s fine. The Commander likes you, Emilia. When you have time, visit the Magic Academy and the Grand Library.”

”Your magical talent will shine far brighter in the Starsea Empire.”

Kanae smiled warmly.

Toward these new arrivals, she carried the confidence of a main wife.

”Eh? L-likes me?”

Emilia tilted her head in confusion, her innocent expression showing a hint of bewilderment.

”...Right, I forgot—she’s been frozen for over a hundred years. Her mental age might still be pretty young...”

...

Meanwhile.

The placement of the Witches of Sin was handled personally by Setsuna and Mio.

For good reason—their Authorities were rather... special.

Inside the Empire’s Grand Magic Academy.

The seven Witches of Sin followed Mio and Setsuna into the vast domed hall.

”Typhon, Daphne, Carmilla, Minerva—you’ll be living here for now. The Angeloids will teach you the Starsea Empire’s rules.”

”Don’t use your Authorities carelessly, and don’t leave the Academy without permission. Understood?”

Setsuna spoke firmly to the four loli witches before him.

”...”

The Witches of Pride, Lust, Wrath, and the coffin-bound Witch of Gluttony all nodded quietly.

Their Authorities were powerful, but their minds were immature—often causing unintentional destruction.

For instance, the Witch of Pride, Typhon—that little loli could simply declare a target ”guilty”, and that person would instantly lose a part of their body.

The terrifying part was that Typhon was an innocent child, entirely devoid of guilt when eliminating those she deemed evil.

If she were to grab a random passerby on the street and say, ”You’re guilty!”, that person would immediately lose an arm or a leg.

Powerful indeed—but without strict supervision, she could easily cause chaos within the capital.

The same principle applied to the others. None of them had yet learned to truly control their Authorities.

”I’ll take care of you all.”

Mio gently patted Typhon’s head.

”When you’ve completely mastered your powers and can ensure they won’t cause trouble for others, you’ll be free to move around as you please.”

”Okay...”

The four little Witches nodded. They felt an inexplicable closeness to Mio.

This big sister was powerful yet gentle. All they needed to do was listen to her.

”Satella, Pandora, Echidna...”

”You are permitted to move freely within the capital, but you must follow the rules of the Starsea Empire. Do not use your Authorities on others at will, understood?”

Setsuna glanced at the remaining three Witches of Sin.

”As long as you abide by that, you’ll enjoy the same privileges as everyone else in the Empire. I’ll do my best to accommodate your requests.”

”...Understood.”

Neither the Witch of Envy nor the Witch of Vanity objected.

One had barely awakened her powers before being abducted here—Satella, full of curiosity, quietly examined her surroundings.

The other had been thoroughly subdued by the Spirit of Origin, her desire to stir trouble temporarily suppressed.

—Better to explore other worlds someday than to cause trouble and get beaten up here.

”I have a question.”

Echidna suddenly raised her hand.

”I want to see everything. I want to understand everything about the Starsea Empire. Commander, will you satisfy my desire?”

”...”

”Are you referring to your thirst for knowledge... or something else?”

Setsuna raised a brow.

”Either is fine, Commander. If you’re willing to sign a contract with me—to let me witness everything you see, hear, and choose—then I’ll grant your every wish.”

Echidna spread her arms dramatically as she spoke.

”Sign a contract? And drink Echidna’s tea, I suppose?”

Setsuna chuckled.

As expected, the Witch of Greed always tried to push her own agenda first.

”The Starsea Empire’s knowledge reserves are vast beyond measure. Instead of studying me, you should start with the Imperial Library.”

”Trust me, Echidna—even if you spent your entire life trying your utmost, you’d barely scratch the surface of our knowledge.”

”Oh?”

Echidna tilted her head slightly, unconvinced. She had immense faith in her own intellect.

The Witch of Greed had mastered all known magic of the Re:Zero world—and even with unfamiliar knowledge, she needed only a little time to completely grasp it.

She didn’t believe there was anything in the realm of knowledge that could truly stump her.

Beep—

Setsuna opened a comms channel.

”Grey, take the Witch of Greed to broaden her horizons a bit. Satisfy her curiosity.”

...

Ten minutes later.

Echidna stood dumbfounded on the lunar research base.

The buildings, the machinery—everything here was unlike anything she had ever seen.

”Oh, so the Commander said you’re quite interested in new knowledge, and that you’re pretty smart too?”

”Perfect. We’ve been short on staff lately.”

Grey’s nanobot body scanned Echidna from head to toe. Somehow, assigning a Witch to a research station still felt strange.

”Of course. I want to understand everything—your history, your science, everything you’ve created and discovered...”

Echidna’s silver eyes sparkled as she eagerly examined her surroundings.

Her insatiable curiosity was burning brighter than ever within the Starsea Empire.

She wanted nothing more than to uncover every secret this civilization held.

”Quite the ambition...”

Grey thought for a moment.

”Alright then, we’ll start with the basics. I’ll introduce you to the fundamentals of interstellar science—like the theories behind starship construction?”

”Fine by me.”

The Witch’s eyes gleamed with anticipation.

”These machines that fly in the sky... are they powered by some kind of magic array? Puppet control spells? Or perhaps the Authorities of special individuals...?”

”Don’t worry, I can master most types of magic—”

”None of the above.”

Grey gestured for her to sit down in a classroom.

He slid a holographic textbook toward her—the Starsea Empire’s standard compulsory education material.

Whirr—

Instantly, countless intricate formulas and abstract equations filled the floating screen, forming a dazzling wall of symbols and numbers.

”Astrophysics, advanced mathematics, radio astronomy... prepare yourself, class is in session.”

”Miss Witch, is your IQ reserve... still sufficient?”

”???”

”Ah? Ehhhhh??—”

...

”Hmm, not bad.”

The next day.

In the Administrative Center, Setsuna reviewed the reports submitted by each department.

The newly arrived girls from the Re:Zero world were mostly studying hard, trying to adapt to life in the interstellar era.

The Witches of Sin, under the guidance of the Magic Academy and the Spirit of Origin, were working on controlling their Authorities—and helping the little lolis among them develop a proper sense of morality and values.

As for a certain Witch who had loudly declared she would learn all the knowledge of the Starsea Empire, she had discovered—after three hours of special tutoring by a nanobot—that she was completely out of her depth.

The Witch of Greed didn’t mix well with scientific concepts. Eventually, she dove straight into the Imperial Library, assisting Rukoa in deciphering the spoils brought back from the Re:Zero world.

And her reward? The library’s endless collection of knowledge—truly the greatest prize for the Witch of Greed.

With that, the Re:Zero world had been fully conquered.

The continent there had been handed over to the Sophons for management. It wouldn’t take long before it was established as a standard vassal world, supplying resources continuously to the capital.

”Commander, it seems we don’t have many neighbors left, do we?”

Yat Sen, after processing a few documents, suddenly remembered something.

Whirr—

Setsuna opened the Hyperdimensional Star Map.

Every world annexed by the Starsea Empire was marked in the same color.

Only a few remained unconquered: Evangelion, Puella Magi Madoka Magica, and the still half-integrated Honkai world.

”That’s true,” he said, ”but there’s still plenty left for us to do.”

”Some worlds haven’t been fully secured yet.”

He brought up a holographic interface and opened his personal memo.

”Among our closest neighbors: Chaldea’s Human Order restoration isn’t finished.”

”The Arbiters haven’t been located yet—but according to Observer and Purifier, they should arrive within a few days.”

”The Previous Era and Current Era integration plans are waiting for the transdimensional ship refits.”

”And then... there are a few more troublesome cases to handle.”

As he spoke, he selected the Goblin Slayer world and the Transformers world.

”The Goblin Slayer world’s Dice God—if we want complete control there, we’ll have to eliminate it.”

”And the Chaos Bringer? That machine’s design looks intriguing. I’ll dismantle it sooner or later—it’s too cool not to.”

Most of the remaining worlds were essentially background settings.

But even background worlds had to be secured completely before they could be considered conquered.

”Oh right, my home world...”

Tohru tilted her head, thinking for a moment.

”Commander, in my world, the forces of Order and Chaos have been at war for tens of thousands of years without a winner. If you helped us, we could easily crush those—”

Before she could finish, Elma’s expression changed drastically.

She yanked Tohru aside and quickly stood in front of Setsuna.

”No!!”

”Commander, you absolutely must not aid the forces of Chaos! You can’t side with evil!”

”You should mediate between the two sides—maintain balance and peace in that world! If Chaos gains the upper hand, it will be catastrophic!”

Bang!—Clap!—

The two dragon girls instantly began wrestling on the spot.

”I’m the Commander’s wife—who do you think you are?!”

”No! I won’t allow it!! I’ll be his wife too—if it’s for world peace, I’ll sacrifice myself!!!”

”Hah?! You dare challenge me?!”

”...”

Setsuna rubbed his forehead.

He realized that he had far more to deal with than expected.

And most of it consisted of long-standing historical issues that would need to be addressed one at a time.

”...”

”But more importantly, my dear husband~”

Just as he was deep in thought, a sultry voice whispered in his ear.

Kurumi’s soft arms wrapped gently around his neck from behind as she pressed herself close to him.

”You’ve finally returned from such a long expedition—and it’s been nothing but work, work, and more work. Haven’t you forgotten something? Hmm?”

Her slender fingers traced along Setsuna’s cheek, gliding downward, slipping past his collar, across his chest.

Her warm breath brushed against his ear as she whispered hotly:

”Or perhaps,” Kurumi murmured teasingly, ”you’ve already had your fill while conquering that world...?”

”Ah~ could it be that girl called Emilia? She’s quite pretty—she and my dear husband make a lovely pair... or maybe it was one of those Witches? Or...?”

Her words flowed lazily, dripping with sensual allure. Every inch of her exuded dark charm and temptation.

”So, you start getting bold the moment Mio isn’t around, huh?”

Setsuna looked up, his gaze meeting her crimson eyes.

Naturally, he slipped an arm around her slender waist and pulled Tokisaki Kurumi into his embrace.

He quite liked Kurumi’s and the Spirit of Origin’s... combination, though Mio was currently busy tutoring the Witches of Sin.

”Well~ who told you to go on such a grand expedition without bringing us along? Poor me, left all alone in the capital~”

Kurumi cupped his face in her hands and leaned in close.

Before their lips met, Origami Tobiichi suddenly appeared beside them, speaking with utmost seriousness:

”Commander, considering you did not bring the Spirit Squad on this expedition, in the interest of fairness, I formally request that you spend an equivalent amount of time with us.”

She began calculating with her fingers.

”Your trip lasted 12 days, 16 hours, and 32 minutes. If we convert that to the standard rate of five sessions per day, you should spend approximately—”

”?”

Setsuna understood the first half, but had some objections regarding the ’five sessions per day’ metric proposed by the Origami genius.

Still, after so many days of restrained self-control in the Re:Zero world, constantly overseeing his squads, he had built up quite a bit of... surplus energy.

Kurumi’s teasing words were all it took to push him to the edge.

”Only that many? Come here—we’ll calculate it together.”

...

A little later.

The massive hull of the Eternal Snowfall was projected across Earth’s outer orbit.

After a faint tremor, the starship’s internal space diverged noticeably from external time.

This was standard procedure after every triumphant expedition.

”Wow... so this is the Commander’s flagship? I’ve hardly ever been aboard before...”

Evileye, Antilene, and the others followed the Angeloids to the upper deck of the command bridge.

The moment they stepped inside, it felt like entering another world.

The scale was overwhelming—a true kingdom among the stars.

The banquet hall was magnificently decorated; above them, the ceiling displayed a projection of endless constellations.

Totsuki culinary team worked tirelessly in the open kitchen, preparing exquisite dishes for everyone aboard the Eternal Snowfall.

Their movements were fluid and dazzling, almost cinematic. Every so often, streaks of rainbow light burst from the ingredients themselves.

When dishes were served, mysterious background music somehow accompanied them.

Shipgirls, Spirits, and Heroic Spirits mingled freely, chatting and laughing as Angeloids glided through the air, offering drinks and desserts to the guests.

Compared to the capital’s public celebrations, this was clearly the Commander’s private banquet.

Only those who had performed exceptionally in the recent world conquest—or those who shared the Commander’s most intimate ties—were invited.

”U-um... d-does my outfit look okay? Is it too formal? Or too casual? I-I’ve never been to something like this before...”

”I-I hope I’m not being disrespectful...”

Albedo’s squad, the newcomers from the Re:Zero campaign, looked nervous and fidgety, unsure of proper decorum.

”It’s fine,” Yat Sen reassured them with a smile. ”During the Re:Zero conquest, your squad’s performance was exemplary.”

”This banquet is the Commander’s personal reward to you.”

”Ah...”

The Guardians and other members of the squad were both astonished and deeply honored.

Guided by the Angeloids, they began exploring the ship.

”By the way, where’s the Divine Commander?”

Antilene, Evileye, and Lakyus circled the bridge but couldn’t find Setsuna.

They had intended to greet him first—but unfamiliar with the layout of the Eternal Snowfall, they nearly got lost.

Eventually, they stopped a pink-haired Angeloid carrying a watermelon.

”...”

Ikaros paused to think for a moment.

”Master is currently in the main suite with Tokisaki Kurumi and Tobiichi Origami. According to projections, they will be... occupied for another 60 to 90 minutes.”

”...Huh?”

Antilene and Evileye exchanged bewildered looks.

”The Supreme One... what kind of ’business meeting’ is he having exactly?”

—

—

40 Advanced Chapters Available on Patreon:

Patreon.com/DaoOfHeaven