Crossover Shipgirls: Building a Dimensional Empire from Scratch

Two days later, the starship landed in the capital of the Starsea Empire.

With the Current Era civilization being squeezed into a parallel universe, the world bubble expedition was temporarily concluded.

”Cosmic Juggernaut possesses precise positioning of world bubbles and the ability to traverse parallel universes within the Sea of Quanta.”

”In the future, you can organize long-range expedition fleets and explore other world bubbles.”

Setsuna handed the navigation logs to Tesla and the others.

”Oh? So I used to be that amazing?”

Vill-V pondered for quite a while. In theory, Cosmic Juggernaut was built by her—but unfortunately, she still couldn’t comprehend its principles.

Edison was overjoyed. They had discovered new research samples once again.

The number of world bubbles and parallel universes within the Sea of Quanta was as countless as grains of sand in the Ganges.

Observing the rules of different worlds and the evolution of civilizations across different eras—even dedicating an entire lifetime to studying them would never become dull.

”The management of the Current Era universe will proceed as usual. There haven’t been major changes in that solar system. The structure of the universe has experienced slight distortions, but the world’s stability is not an issue.”

Setsuna continued.

”As for Miss Astrologos...”

Everyone’s gaze turned in unison toward the petite girl following at Setsuna’s side—who looked exactly like Theresa.

”For now, you’ll live here temporarily. If you have any questions, you can ask Sophon and Yat Sen.”

”We’ll arrange accommodation for you shortly. An Angeloid will explain the important matters of the capital.”

”Oh...”

Astrologos curiously surveyed this new world.

It was countless times larger than the world bubble she had lived in. As far as the eye could see were fantastical creations of the interstellar age.

And beside Setsuna stood many beautiful girls she did not recognize.

”Very well... I understand...”

”Wait!”

From the onlooking crowd, Theresa popped her head out. Upon seeing the girl who looked identical to herself, the two froze at the same time.

”Why do you look exactly like me?!”

Aside from their clothing, whether it was temperament, appearance, hair color—even their height—there was not the slightest difference.

”A world bubble is essentially a projection of an original world. You can regard Astrologos as your shadow in another world, Theresa.”

Setsuna rubbed Theresa’s head.

”Of course, she’s also an independent individual. Astrologos is Astrologos—the ruler of Emberya.”

”She’s much younger than you. A genuine young girl. In terms of seniority, she’d have to call you Grandma.”

At this time, Astrologos had undergone neither any super-transformation surgery nor genetic enhancement. She was just an ordinary human.

Meanwhile, due to changes in the timeline, Theresa was older than before—even senior to Cecilia.

”Ah...”

Astrologos lightly covered her face with her feather fan.

”Grandma Theresa? Does that mean you are my ancestor?”

”Hey! You’re not allowed to call me Grandma! ...And Auntie is off-limits too!”

Theresa protested, stomping her feet.

”You two get along nicely. Theresa, show Astrologos around the Valkyrie Academy and explain the situation of the Starsea Empire.”

”In the future, we might ’fish up’ a few more Theresas. Hmm... I’ll leave it all to you.”

Setsuna pinched Theresa’s cheek again.

”Huh?!”

Teaching herself—no matter how she thought about it, it felt strange.

And when Setsuna mentioned bringing back even more Theresas in the future, she felt a faint headache.

”Fine then. Miss Astrologos, I’ll treat you as an ordinary citizen of the Starsea Empire, alright?”

”No problem! I am here to conduct an inspection... If the Starsea Empire truly is as powerful as I imagine, then I will entrust my world to Mr. Assassin.”

The two Theresas walked off one after the other.

She led Astrologos through the capital, explaining its overall layout and functional districts.

”This is the administrative center. That’s the harbor district. Over there is the Chaldea Heroic Spirit residence...”

”Uh, species? Here, take this tablet. Read the information yourself later. There are many transcendent existences within the Starsea Empire—completely different from the gods you understand.”

”Territorial size? The Empire’s domain is measured in universes. As for our core territory... wait, let me check the star map. The expedition fleets expand too quickly...”

Astrologos was overwhelmed by what she saw.

Although her expression remained calm, her heart was already in turmoil.

”So... Mr. Assassin wasn’t lying?”

”This place is incredible...”

...

After settling Astrologos and resolving the residual issues from the Previous Era overlapping the Current Era,

Setsuna handed the follow-up exploration tasks for the world bubbles and the Honkai universe to the Research Division.

”Phew—”

”Three eras, plus world bubbles and parallel universes. Mm, all settled.”

He marked the Hyperdimensional Star Map. Even if something was discovered in a world bubble later, their scale was limited.

A round trip wouldn’t take long, and most of the work could even be delegated to Edison and the others.

”Mm...”

After arranging the remaining trivial matters, he leaned back in his chair and stared at the holographic dome for a while.

”Commander, do you have any plans next?”

Belfast gently placed several refreshments on the table and massaged his shoulders.

Her silver hair brushed against his face, tickling slightly.

”If you are feeling fatigued, perhaps you should rest for a while?”

The head maid’s voice was soft and refined. The strength of her hands was just right, and the ample softness at her chest happened to rest perfectly against the back of Setsuna’s head—warm and gentle.

Setsuna couldn’t help but sigh inwardly. A Royal maid was truly a Royal maid. Professional.

”I’m thinking about the next world to conquer.”

On the Hyperdimensional Star Map, he tapped several remaining worlds.

A Certain Magical Index, Puella Magi Madoka Magica, Tengen Toppa Gurren Lagann, Problem Children Are Coming from Another World, Aren’t They?

Among the high-difficulty worlds discovered last time, after dealing with the easiest—Nyaruko—and then conquering the weakest—No Game No Life,

What remained were all heavyweights.

If he continued following the strategy of starting from the weakest, the next challenge would be the world of A Certain Magical Index.

”Commander, is it difficult?”

Belfast did not understand the magic side very well. As she massaged his head, she asked softly.

”Thanks to Nyaruko, in terms of overall strength we should be stronger than the Index world.”

Setsuna glanced at Nyaruko and Shabu playing games with controllers nearby.

If he had encountered the Index world earlier, he wouldn’t have dared to go there without first casting concealment magic and bringing along a few dragon girls and Spirits.

Now the capital housed a group of Cthulhu girls. They could even call over more Outer Gods from Nyaruko’s world. After obtaining Suniaster, they could wrestle with those Magic Gods directly.

”However... if we want to incorporate the entire world and all the authorities of the Magic Gods, that would be troublesome.”

”Inter-world warfare is mutual. Fighting natives is one thing. Launching full-scale war against a Level IV world could produce unexpected consequences.”

”Perhaps I should first find a way to bring the magical girls over? Or wait until the Aetherophasic Engine is completed?”

Various strategies surfaced in his mind.

He needed some time to sort them out.

”Belfast believes in you, Commander. Whatever order you give, we will carry it out without hesitation.”

Her voice was gentle yet firm.

”Mm... If work has been exhausting lately, perhaps changing environments might help refresh your thinking?”

”A new hot spring was recently completed in the harbor district, built to five-star standards. Would you like to try it?”

”Oh? Sure.”

Setsuna thought for a moment. He had been traveling back and forth between several worlds recently and hadn’t visited the harbor district in a while. He agreed casually.

After agonizing over it for so long, he might as well clear his mind.

”Wow~”

Beside them, Elysia rested her chin on her hand, watching Setsuna with keen interest.

”A girl taking the initiative to invite you to a hot spring? Commander, you’re impressive~”

”Can you take me along? I want to have a look too. The shipgirls are all so cute~”

She was curious about those sea-bound spirits. Especially after learning that they were founding members of the Starsea Empire—and that even Bulins were part of the shipgirls—the harbor district seemed even more mysterious to her.

”You? Coming to the harbor district with me?”

Setsuna raised an eyebrow.

”Sure. But don’t regret it.”

...

”Wow—”

Led by Belfast and Yat Sen, Elysia, along with Griseo—who had been staying by Setsuna’s side—entered the Azure Lane harbor district.

”Commander, this place is huge.”

Griseo habitually tugged at the corner of Setsuna’s clothes.

The harbor district was essentially a small city.

It included small-scale armories, repair facilities, a naval academy, shipgirl dormitories, and more. The futuristic layout and the shipgirls everywhere left Elysia clicking her tongue in amazement.

”So the Commander has been living surrounded by so many girls all this time. Not a bad life~”

She looked around. Shipgirls came and went, and quite a few were visiting from other harbor districts.

As soon as they saw Setsuna, the shipgirls gathered around.

”Commander, Commander, will you play with Yukikaze, nonoda?”

”Yuudachi wants to join too, poi?”

”The moon is lovely tonight. Would you care to accompany me, Shoukaku...?”

The smaller shipgirls crowded around him, acting cute, while the older ones warmly extended invitations for dates.

They chirped endlessly, surrounding him completely.

”Mm... There are too many of you. I’ll spend time with everyone when I have the chance.”

Setsuna responded with a smile, one by one.

He was already well accustomed to being surrounded by shipgirls like this.

”Hiss...”

Elysia had never seen such a scene before. She quietly poked Setsuna.

”Commander, how many girlfriends do you have?”

”You guess.”

”Uh...”

Elysia puffed her cheeks and started counting on her fingers.

During her time in the Starsea Empire, she had already gotten to know quite a few of the people around Setsuna.

”Let me think... Richelieu and Yat Sen at the administrative center, that dragon girl with the tail, Nyaruko who always comes to play games, that silver-haired Spirit...”

”One, two, three, four, five...”

She quickly ran out of fingers, and there were still many she hadn’t even met. In the end, she guessed wildly:

”Uh, around fifteen or sixteen?”

”That was just the number from the night before last.”

”???”

Elysia blinked, unsure whether he was serious or teasing her.

Setsuna pointed toward several massive structures on the distant sea horizon.

”This Azure harbor district, plus the nearby Kancolle harbor, the Arpeggio harbor, and the Siren harbor. Most of the shipgirls you can see are either my wives—or future wives. Oh, according to shipgirl terminology, they’re called oath ships.”

”Ah?!”

Elysia’s pupils trembled.

She already knew that as the ruler of the Starsea Empire, Setsuna wasn’t someone who could be judged by common standards.

It was normal for many girls to admire him.

But the combined scale of several harbor districts was simply outrageous.

And that didn’t even include other races. In the capital alone, there were Heroic Spirits, Spirits, horse girls, and all kinds of beings from other worlds.

”Th-That can’t be true, right?”

”Commander, casually saying someone is your girlfriend isn’t a good habit~”

Elysia stubbornly argued.

”Don’t believe me?”

Setsuna casually called over a shipgirl.

”Cheshire, I’m going to the hot springs. Want to come along?”

”Meow?”

The cat-eared girl immediately pounced into Setsuna’s arms.

”Darling! This is the first time the Commander has invited Cheshire personally! Wait just a moment—I’ll go change right away!”

”Atago, want to join?”

”Oh my, does the Commander have something in mind for your big sister? That’s fine—I feel the same. Just a moment~”

”...?”

Elysia stared at the scene.

In any other place, this kind of line would be treated as sexual harassment without question—but the shipgirls agreed instantly, without even thinking.

She couldn’t comprehend it.

Before long, the group had grown several times larger.

”Ah, everyone’s turned pink. Some of the shipgirl sisters are even giving off hearts.”

Griseo scratched her head.

Her perception was as sharp as ever.

Being in the harbor district, she felt like she might start turning that color herself.

”???”

Elysia was completely stunned by Setsuna’s popularity.

After thinking for a moment, she tugged at him again.

”Um... I mean, with so many girls, you can’t possibly take care of all of them, right?”

”Heh?”

Setsuna snorted.

”You know nothing about power.”

...

Before long, surrounded by shipgirls, the group arrived deep within the harbor district, at an artificial hot spring.

After expansion by the Bulins, the Azure harbor district had become enormous.

At a glance, it looked less like a hot spring and more like a lake.

Dense forests surrounded it, and dozens of hot spring pools of varying sizes were scattered throughout, steam rising gently with a faint scent of sulfur.

It had an ancient, elegant atmosphere—completely unrecognizable as something artificially constructed.

Many shipgirls were already soaking inside. Upon seeing Setsuna, they waved enthusiastically.

”Commander, Commander, come here! Join us!!!”

Quite a few Bulins were also bathing. They all looked identical—without the nameplates on their chests, it was impossible to tell them apart.

”Wow—”

Elysia marveled at the scale. Even in the Previous Era, she had never imagined such a scene.

”Today is the weekend, so there are quite a lot of people in the hot springs. But the largest pool is always reserved for the Commander, bruin!”

The Bulins enthusiastically handed out towels and bathing supplies, guiding everyone into the baths.

Since the harbor district only housed shipgirls—and occasionally visitors like Heroic Spirits or dragon girls—there was no need for separation.

Even the changing rooms were completely open.

Setsuna finished changing first and immersed himself in the hot spring.

The water seemed to contain some kind of calming magic, instantly refreshing the mind.

”Commander-sama, Taihou will accompany you~”

”Shall you wash Taihou first, or shall Taihou wash you... or shall we eat Taihou first?...”

A certain yandere shipgirl squeezed into Setsuna’s arms.

She subtly tugged at the towel wrapped around her chest, drawing his gaze.

”Oh dear, it seems my hairpin fell in. Commander, could you help me retrieve it?”

Taihou took Setsuna’s hand and guided it downward.

”Ahem, Taihou, please be mindful. Now isn’t appropriate.”

Richelieu cleared her throat and stepped into the water, naturally leaning against Setsuna’s other side.

Surrounded by shipgirls, he was instantly enveloped by warmth and softness.

Tap, tap, tap—

”Eh?!”

On the shore, Elysia had just finished changing. With her pink hair tied up, she stepped into the hot spring area in slippers.

The moment she saw Setsuna soaking together with the shipgirls, she froze in shock.

”W-What?! Mixed bathing?!”

”Why are you here too?!”

She gasped, clutching her chest as she took two steps back.

”?”

”Come on, this is the harbor district’s hot spring. Isn’t it normal for me to bathe with the shipgirls?”

Setsuna raised an eyebrow and casually invited her:

”There’s still space here. Want to join us?”

”Huh?!”

For the first time, the ever-composed, teasing pink elf was completely flustered.

Teasing others was easy—but when things became real, she was utterly unprepared.

Not only her beautiful face, but even her fair neck and shoulders flushed red. She hurriedly pulled her towel up higher.

”N-No, no, what are you saying?! Th-This is too sudden!”

”I—I—I’ll find another place!”

”Oh. Then go over there. Otherwise, it might get noisy here later and disturb you.”

Setsuna pointed her in a direction.

”???”

”Huh?!”

Elysia fled in a panic, jumping into another pool with a splash.

Only when the steam blurred the figures across from her did she finally relax.

”What kind of person is this?!”

Half-submerged in the water, she blew bubbles on the surface.

She felt like her worldview had just expanded.

Improper. Completely improper.

And what did he mean by ”noisy”? No matter how she thought about it, something felt off.

Yet seeing all the shipgirls crowding around the Commander while her side remained empty, she felt oddly unwilling.

”What is this called... you’re not allowed to join the party?!”

She recalled some strange knowledge she had picked up from the Starsea Empire’s internet.

”Maybe I should try to fit in and go over there with them? No no no, we’ve only just met...”

”No way! Not happening! How can everyone bathe together like that?!”

She splashed the water a few times. The Honkai energy she released briefly froze a thin layer of ice over the spring, which quickly melted again in the steam.

”...Is she having some kind of mental conflict? Does she dislike the Commander?”

Not far away, Sirius looked at Elysia in confusion as she talked to herself.

”No, she just isn’t used to the interpersonal relationships here yet.”

The head maid, experienced as ever, deftly tied up her hair.

”More importantly... let’s go. We can’t let the others get ahead.”