Crossover Shipgirls: Building a Dimensional Empire from Scratch

”Bulin Engineering Team 201 reporting in!”

”Bulin Engineering Team 202 reporting in!!”

”Warning! A massive wave of Bulins is approaching!!!”

All idle Bulins of the Starsea Empire were mobilized.

Tens of millions of golden, purple, and rainbow Bulins boarded transport ships and landed on the Eternal Snowfall.

Under the command of the Engineering Division, they lined up and entered different universes in orderly formation.

”Engineering Teams 156 and 157, proceed to Universe No.1 of the Eternal Snowfall—Silver Garden.”

”...Engineering Teams 188 through 210, bring the Angeloids and head to Universe No.15. Take instructions from Akashi and prepare the megastructure construction platforms.”

”...Engineering Team 233, go to Universe No.16 and construct the starship assembly plant.”

For a time, the ship bustled with activity.

Every day, groups upon groups of Bulins could be seen carrying tools as they boarded the ship together with Angeloids.

Gudako made a rough estimate. Each engineering team had anywhere from several thousand to over ten thousand Bulins.

Every time she opened her eyes in the morning, all she saw were Bulins rushing back and forth.

If they all stayed inside the Eternal Snowfall, they would completely fill the bridge and every corridor.

But once dispersed across the sixteen miniature universes, they seemed astonishingly sparse.

Cheerful Bulin voices echoed everywhere.

”Buli? Where’s the entrance to Universe No.5, buli?”

”Burin! Bulin needs more helpers, burin! Commander, can you transfer more Manjuu over, burin?!”

”Purin! My drill is the strongest tool!!!”

Each type of Bulin had its own verbal tic. After listening long enough, it became strangely addictive.

”This is probably the largest-scale starship renovation in the history of the Starsea Empire, buli.”

Gudako sighed, then suddenly smacked her own forehead.

”Wait, why am I saying ’buli’?! Have I been infected after staying with them too long?!”

Inside the other universes within the starship.

Setsuna moved from one to the next, filling them with creations.

”Universe No.1 will be the bridge residential zone. Universes No.2 and No.3 will remain as reserves. Universes No.10 through No.15 will be used to construct wonders... Universe No.16 will serve as the dock...”

”Hoo—”

After creating several more stars.

He let out a deep breath and returned to the bridge of the starship.

”That’s enough for today. I haven’t planned the remaining universes yet, so we’ll leave them empty for now and develop them once there’s a proper arrangement.”

Even with his extraordinary stamina, continuously performing miracles like handcrafting stars and splitting heaven and earth in a short period was mentally taxing.

”You’ve worked hard, Commander.”

Belfast gently brewed him a cup of tea and stood behind him, massaging his shoulders with just the right amount of pressure.

”Miracles like this... we wouldn’t even have dared imagine them before.”

”Not quite enough.”

Setsuna smiled.

”This is only stellar-level Genesis... If I want to construct miniature universes on the scale of full cosmic structures, I’ll need creative power on the same magnitude.”

”At the bare minimum, I’d have to be able to construct something the size of the Milky Way in an instant.”

Everything inside a miniature universe had to be handcrafted.

The advantage was total freedom—whatever you wanted, you could shape. However you wanted it, you could create it.

The downside was that everything started from zero. From a grain of sand to a blazing sun, it all had to be made personally.

There were hundreds of billions of planetary systems in the galaxy. Creating them one by one would take until the end of time. He had to find a way to further expand his capability to construct miniature universes.

”Oh—”

Mio beside him let out a soft exclamation.

”Husband wants to create an entire galaxy at once?... It’s hard to imagine...”

”If only I could help you more. Unfortunately, I’m not skilled in this kind of magic...”

”It’s fine. Let the Bulins build gradually for now. As for expanding the scale, I have some ideas.”

Setsuna rubbed Mio’s head and pulled the Spirit of Origin into his arms for a playful squeeze.

”When the time comes, your activity space aboard the Eternal Snowfall will be even larger. You’ll have several universes to play in.”

”...”

Gudako narrowed her eyes.

”Oh sure, sure. And then crank up the time dilation to tens of millions of times, just like those civilizations hiding in miniature universes.”

”They hide inside to escape dimensional collapse, and you’re in there throwing century-long parties, huh?!”

...

There was no day or night aboard the Starbase. Everything depended on the starship’s internal holographic dome for adjustment.

By evening, Setsuna finished a day of Genesis work and returned to his room.

The composite universe renovation plan of the Eternal Snowfall was a long-term project. Fortunately, construction took place inside the miniature universes, so the starship itself was not heavily affected.

If necessary, as long as they notified the Bulins working inside beforehand, the ship could set sail at any time.

”Mm...”

Setsuna leaned back in his chair, staring out the porthole at the sea of stars, spacing out for a while.

The past few days had consumed a great deal of stamina. He felt slightly fatigued.

Before he knew it, he closed his eyes and drifted into a brief nap.

Zzz...

Zzz... Zzz...

The starship had automatic temperature control, constantly adjusting to a comfortable level.

However.

After sleeping for a while, half-awake and half-asleep, Setsuna suddenly felt as though he had been smothered awake.

Groggily, he opened his eyes.

So white—no, so big.

An overwhelming sense of justice pressed against his face.

”?!”

Looking again.

He seemed to be lying on a bed.

”???”

”Aa... Aaa...”

A voice like a lullaby drifted beside his ear.

”!!?”

”What’s going on? Did I get night-attacked?!”

Setsuna froze for a few seconds.

It felt different from previous night attacks. Taihou and Origami usually went straight to the main event from the start.

Lifting his head, he realized he was being cradled in Tiamat’s arms. She was gently patting his back in rhythm, humming softly.

Like soothing a child to sleep.

”Aaa...”

”Master, you... woke up?”

Tiamat’s voice was full of warmth and motherly affection as she lowered her head, red eyes gazing at him.

”Uh... what are you doing?”

”Master, recently very tired.”

Tiamat said.

”Creating worlds is exhausting, right?... Master fell asleep in the chair.”

”I want to help more. If you rely on me more, I will be very happy.”

”...”

Being tired was true. Setsuna just hadn’t expected to be treated like a child by Tiamat.

”Come to think of it, you’ve been creating so many worlds with me. Aren’t you tired?”

”I am Beast. Using Sea of Life is easier than Master creating stars and planets...”

She answered slowly, word by word.

She was only responsible for constructing planetary ecosystems. The effort required was far less than forging stars and planets from nothing.

”If Master wants to sleep a little longer, you can.”

”I will stay with you.”

As she spoke, she hugged him a little tighter.

The tables had completely turned.

But Setsuna had to admit—the soft, white pillow was extremely comfortable.

This was a brand-new experience!

Tiamat sang beautifully, too.

She seemed to possess the ability to freely alter her size—not only switching between human and dragon forms, but also subtly adjusting her body structure.

At this moment, in order to emphasize her identity, Tiamat was undoubtedly in full ”luxury-class” form.

A normal luxury-class—not the kind larger than a small spaceship.

”Good...”

Tiamat sincerely focused on lulling Setsuna back to sleep. It was something she had learned from the Starsea Empire.

As she continued, she suddenly sensed something unusual and reached down to pinch it.

She blinked.

”Hm?... Eh? Master?!”

”That’s a normal reaction.”

Setsuna cleared his throat.

Sure enough, with multi-core drive, even after massive stamina consumption from creating miniature universes, recovery was rapid.

”Mm...”

Tiamat thought for a moment.

”Ah, I forgot... Master is also an adult.”

”!?”

”It’s okay.”

Tiamat opened her arms.

”Master, I will always, always protect you. You can rely on me. I will accept everything about you.”

”...”

...

”Mm... ah.”

In the early morning, when sunlight simulated by the holographic dome streamed in through the porthole...

Setsuna was once again smothered awake.

In front of him was still that soft, white—and very large—”pillow.”

”Ah, Master—you’re awake? ...”

Tiamat held him gently, her expression filled with warmth.

Her aqua-blue hair draped loosely over her body, outlining a nearly perfect figure.

”Master really has so much energy, hehe...”

”But holding onto my horns like that isn’t a good habit.”

As she spoke, Tiamat lightly pinched him, like scolding a child.

”???”

Setsuna felt like their roles had somehow been forcibly reversed.

When Tiamat said she could accept everything, she truly meant it.

But her horns were like a steering wheel—sometimes he couldn’t help but grab onto them.

”Do you want to sleep a little longer? Or get up now? Or...”

Tiamat glanced at the time and tilted her head.

”Ah, it seems that won’t work. It’s already morning. It wouldn’t be good to delay too long.”

”Master, I’ll reward you again tonight.”

”...”

Far too maternal.

Setsuna felt that Tiamat was an entirely new kind of experience.

”Oh, right.”

Tiamat suddenly seemed to remember something.

”Master, while managing a nation is important, finding a good partner is also important, you know?”

”Do you have a partner? When you find one in the future, remember to bring them to me. As long as they pass Tiamat’s review, no one unsuitable will remain.”

”???”

Setsuna was full of question marks.

”Are you acting like a parent arranging a blind date for their child?!”

”Mm!”

Tiamat nodded seriously.

”Master’s partner... must be someone who can take care of you like I do. Otherwise, wouldn’t they only cause you trouble?”

”So just leave it to Tiamat. I will personally evaluate each and every one!”

”...Ahem, the situation might not be quite what you think.”

Setsuna briefly explained.

At first, when Tiamat heard names like Yat Sen and Richelieu, she nodded repeatedly.

”Mm, mm...”

”That black-haired girl, and the blonde one, right? They are very efficient at work. Very suitable to assist you.”

”Tohru? She’s a dragon? Dragons don’t usually have the best temper. Does she listen to you?...”

”Erina? Mm... eating is indeed very important.”

Tiamat analyzed each girl seriously from a purely practical perspective.

But when Setsuna continued listing name after name without end, Tiamat was stunned.

Her crimson eyes filled with confusion—and a hint of shock—as she looked at him.

”So many... ah, it seems I underestimated Master?”

”Mm... if Master doesn’t have enough time, I can help take care of them. After all, they are all my children.”

Tiamat generously declared that, as the mother of everyone in the Starsea Empire, it was only right for her to help manage Setsuna’s ”harem.”

”...I’ll handle it myself.”

Setsuna was at a loss.

Her way of thinking was completely different from everyone else’s.

Aside from a few exceptions like Nyarlathotep, in Tiamat’s eyes, almost everyone was her ”child.”

...

”Uh... so what exactly is this situation?”

Half an hour later.

Gudako stared wide-eyed at Tiamat, who was clinging closely to Setsuna.

The final boss of the previous Singularity, one of the Seven Beasts of Humanity—now completely captured by the Commander.

Then again, considering even Outer Gods hadn’t escaped him, a Beast didn’t seem that surprising.

”Fulfilling a child’s wishes is only natural.”

Tiamat opened her arms, revealing her broad embrace.

”Whatever Master wants, whatever he desires, I will grant it.”

”Being relied upon by Master... makes me happy.”

”???”

Gudako felt something was very off.

”Then what are you to him right now?”

”I am Master’s partner. We are going on a date today.”

Tiamat linked arms with Setsuna, smiling innocently.

”Mm... but he is also my child. I will always take care of him.”

”Aaaaahhhh!!!—”

Gudako clutched her head, utterly despairing at Tiamat’s worldview.

”...Eh?”

”Then what about me?”

From the crowd, a white-haired girl suddenly popped out.

Kiana had only come to observe the reconstruction of the Empire’s flagship and take a look at the miniature universes.

She hadn’t expected to walk straight into such an ethical disaster.

”Um, the Commander is my dad, so if Goddess Tiamat is the Commander’s mom...”

”Then... Grandma Tiamat?”

The white-haired girl looked at Tiamat in shock.

Despite looking about the same age as Cecilia, her seniority had suddenly jumped up a generation.

”It’s Mother~”

Tiamat gently patted Kiana’s head.

”You, Cecilia, and everyone else... are all my children.”

”Huh?!”

Kiana’s brain went into overdrive for several minutes, completely unable to untangle the relationships.

System crash.

”Ah!”

Tiamat suddenly looked at the chattering group of girls and clapped her hands.

”I understand now!”

”Understand what?”

”Earlier, Master mentioned a term—’party.’ I didn’t understand it at the time.”

Tiamat had a sudden realization.

”Now I get it. It means everyone together, like what Master and I did yesterday, right? Mm... what a strange custom in the Starsea Empire.”

”So does that mean I can join you all for future parties as well?”

She said it with complete seriousness.

”...”

Silence fell over the scene like death.

Setsuna sighed and patted Tiamat.

”Alright, Tiamat. I know you’re very smart.”

”Some things don’t need to be explained so clearly.”

...

After the commotion died down.

Setsuna continued directing construction within the miniature universes of the Eternal Snowfall.

He noticed that as development progressed, his own power was gradually increasing.

This feeling was especially strong in Universe No.15, where they were constructing the framework of a Dyson Sphere.

Although it was only a rough structure, and the energy extracted from the star was less than one-thousandth of a complete Dyson Sphere, he could clearly feel the power being transmitted back.

”Because the energy of the miniature universes and the Eternal Snowfall’s main body are interconnected.”

Observer said, tapping on a holographic interface.

”Energy produced within the miniature universes can be extracted and supplied to the Eternal Snowfall.”

”If necessary, you could even convert an entire miniature universe into pure energy and use it for a Genesis-level attack. Of course, that would also burn the universe away.”

”...Burn, my miniature universe?”

Setsuna muttered, half understanding.

Using a miniature universe as ammunition would undoubtedly be countless times more powerful than Fallen Star Lance.

The only drawback was the cost—astronomically expensive.

After shaping a few more planets and assigning tasks to the Bulins.

Bzzzt—

A holographic interface opened before him.

A communication from Chaldea connected.

”Mr. Setsuna, Chaldea is ready. What about your side?”

Roman’s projection appeared, immediately noticing the massive construction underway on the Eternal Snowfall.

”Yo.”

Setsuna greeted casually.

”Good timing. Heading into the final battle?”

”Mm. Chaldea is about to make contact with the Final Singularity and begin spacetime fusion.”

”This will be the final battle to save human history.”

—

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