Crossover Shipgirls: Building a Dimensional Empire from Scratch

”Uh...”

In the boundless darkness, Gudako slowly opened her eyes.

Before her stood a colossal metal gate that seemed to connect heaven and earth, its surface etched with intricate patterns.

Eerie mist filled the surroundings.

She glanced down at herself. Her body was still intact, but she was in a near-spiritual state.

She couldn’t summon Strelizia, and most of her magic and skills were unusable.

She had indeed died completely, her soul having fallen into the Underworld.

Bzzz—

A holographic interface opened before her eyes.

”Reporting to the Commander, I have died. Feeling great.”

Gudako saluted Setsuna.

Pfft—

Setsuna was both amused and exasperated by her antics.

”Alright. You’re probably Ereshkigal’s first customer in the Underworld.”

”She’s been renovating the place these past few days. Take a look around and then have her send you back.”

After the Underworld was established, the cycle of life and death within the Starsea Empire had become an internal loop. It was merely a matter of staying somewhere else for a while.

”Then what about my body? Commander, you wouldn’t take advantage of me while I’m unconscious and do this and that, would you?”

The Human Evil tilted her head.

”???”

”Keep talking nonsense and I’ll have Ereshkigal lock you in the Underworld for tens of thousands of years.”

The two bantered for a bit.

Clack—

The gates of hell slowly creaked open before her as she officially stepped into the Underworld.

Dim light filtered through the ghostly mist from somewhere in the distance.

Unlike the desolate Underworld of a few days ago, it had changed once again.

The first thing she saw was a river stretching across before her, running from one end of the horizon to the other, with no visible beginning or end.

The river’s surface was pitch black, faint ripples barely visible.

Across the river bloomed fields of crimson flowers, endless and boundless, carpeting mountains and plains all the way to the horizon.

In the dim environment, they appeared especially enchanting and eerie.

”Wow—”

Gudako lavishly praised Ereshkigal’s taste.

”So pretty... Now this really feels like an Underworld.”

She continued forward, crossing the river and the sea of flowers.

Beyond them lay another gloomy road.

She looked around curiously as she walked. It was clear that, building upon the foundation Setsuna had provided, Ereshkigal was remodeling the Underworld to better fit the definition of an ”Underworld.”

Suddenly, as she walked—

The mist ahead grew thicker.

Clack, clack—

From the distance came heavy footsteps, along with the dragging sound of chains scraping against the ground.

”Who’s there?”

”Hmph.”

Several figures emerged from the darkness, standing before her and looking down at Gudako.

The leader was extremely tall, clad in dark bronze armor and wearing a mask that obscured his face. Black mist seeped from his body, like a ghostly general.

Behind him followed a small squad of spirit soldiers, their faces equally obscured, faint black fog swirling around them.

”Huh? What’s this? Ghost generals and spirit soldiers? Where did you guys come from?”

Gudako craned her neck, curiously examining the towering figure.

Clank!—

Two spirit soldiers stepped forward without a word, shackled her wrists, and dragged her inward.

”Eh? Eh? Eh???”

”What the heck is this?!”

Gudako panicked.

Within the Underworld, her strength was suppressed. She had no opportunity to resist.

After Ereshkigal’s power surge, this rule-based suppression had grown even stronger. In soul form, she was practically no different from an ordinary person.

”I’m a VIP!!”

”I bled for Chaldea! I fought for humanity! I want to see Ereshkigal! I want to see Ereshkigal!!!”

She shouted and protested as the spirit soldiers dragged her deeper inside.

The further they went, the colder it became.

Looking around, she realized that a ghostly city had been constructed here, filled with patrolling spirit soldiers and ghost officials.

They carried blades, wore ancient-style armor, and were surrounded by strange, ominous power. They truly resembled beings from myth.

”Why did you build the Underworld into a full-on Hell Court?! Isn’t this even more over-the-top than what the Commander made for you before?!...”

The spirit soldiers dragged her into a dark and imposing grand hall.

She looked up.

A ”figure” wearing an imperial crown with hanging beads and dressed in a wide-sleeved robe with layered lapels sat upright at the front.

Its presence was overwhelmingly powerful, almost making it impossible to raise one’s head to look directly at its face.

Bang—

The figure struck the sound block, its voice solemn and deep.

”Ritsuka Fujimaru, your lifespan has ended.”

”Now that you have entered the Underworld, your punishment and next life shall be determined according to the good and evil of your deeds.”

It took out a ledger and began flipping through it.

”...”

”Though you have committed many misdeeds in your daily life, in consideration of your merit in saving humanity, your merits and faults cancel each other out. You may enter reincarnation once more.”

”Reincarnation? Where did I end up?! Is this even the Underworld anymore?”

Gudako was completely confused.

No matter how she looked at it, the one seated above was clearly a Yama King. Where was the judge?

Then the Yama spoke again in a low voice:

”There are currently no reincarnation slots available within the Starsea Empire’s core territory... Your next life will be reincarnated in: Holy Terra.”

”You shall live again as an ordinary citizen in a hive city.”

”???”

”Huh?! Wait a second!!!”

Gudako was horrified.

”I’ve accumulated virtue all my life! Who the hell committed many misdeeds?! Explain yourself first?!”

”And what the heck is Holy Terra?! Who wants to reincarnate in that hellhole?!...”

”Wait, wait—Is that even within our territory?! Isn’t that outside the Starsea Empire’s Underworld jurisdiction?!...”

No matter how loudly she protested, the spirit soldiers dragged her forward without hesitation.

In the face of absolute power disparity, resistance was meaningless.

Seeing that she was about to be dragged across the Bridge of No Return, Gudako completely lost her composure.

”Commander! Commander! Hurry and call Ereshkigal out?!”

”Did I die in the wrong place and get detained by another Hell Court?! Don’t actually throw me into Terra alone, okay?!”

With tears streaming down her face, she strongly suspected she had died in the wrong posture, causing a bug in Ereshkigal’s Underworld system and letting another Underworld snatch her soul away.

”Aaaahhh!!!—”

Just as she was screaming—

”—Don’t be scared.”

Snap!—

A crisp snap of fingers.

The spirit soldiers, ghost officials, Yama, and everything before her froze in place.

A blonde girl with twin tails stepped out of a portal and made a face at Setsuna through the holographic interface.

”Hi, Master~”

”That’s right. You’ve indeed entered my Underworld.”

”I’ve been doing a technical upgrade on it... After going back, I thought about it. With such a large Underworld, if I’m going to manage other worlds in the future, the workload will definitely be huge. I’ll need some helpers.”

Ereshkigal revealed a mischievous smile.

”So I decided to test things out with my first customer. Just a little joke. Sorry~”

”Ha—”

”Huh???”

It took Gudako quite a while to recover. She took several deep breaths.

”You almost scared me to death! Is this what VIP treatment in the Underworld looks like—getting reincarnated into Holy Terra?!”

”I didn’t offend you or anything, did I?!”

”Mm... I just wanted to test it with my first customer. I’ll treat you to a meal later.”

Ereshkigal clasped her hands together.

”...Huff.”

After calming down, Gudako pointed at the motionless spirit soldiers.

”Did you make them all?”

”Mm.”

Ereshkigal nodded.

”More precisely, the Bulins made them. They’re a fusion of some technology from the magic academy—basically a combination of summoning magic and engineering. In other words, robots with magical capabilities.”

”In the Underworld, most souls can’t defeat them.”

As she spoke, she took out a magic scroll, spread it on the ground, and poured magic into it.

Weng—

The reverse summoning system activated. The spirit soldiers and ghost generals all turned into streaks of light and were sealed within the scroll.

Gudako was familiar with this move. She often used scrolls to summon Strelizia.

”This is Hell Court No.1 Experimental Model. It’s not fully completed yet. The Terrace of Nostalgia, Meng Po Soup, and the various hells haven’t been prepared.”

Ereshkigal weighed the five or six scrolls in her hand.

”Master gave me some inspiration. In the future, I plan to create more Underworlds in other mythological styles.”

”If needed, I can switch between them at any time—or even let them coexist.”

”...”

The people watching through the holographic interface looked at each other, feeling as if they had stepped into a cyber Hell Court.

”You’re even building hells...?”

Gudako suspected Ereshkigal had learned something strange from books.

”Wait. What was that about reincarnating into other worlds? Are you seriously planning that?”

”Mm...”

Ereshkigal paused.

”I’m very interested in the concept of reincarnation in classical mythology and want to study it more. Across different systems, the management methods of the Underworld are quite similar.”

”The Starsea Empire governs many universes. If my power grows strong enough, I should be able to control reincarnation within the Empire’s territory.”

”Mm... Although the core territory itself doesn’t enter reincarnation. Still, I think I could help Master with some things?”

This authority was indeed incredibly impressive, though Ereshkigal had yet to think of more advanced applications.

Gudako’s expression turned strange.

If the goddess of the Underworld’s management scope expanded to encompass all worlds, her authority would be terrifyingly vast.

”So in the future, if anyone offends the Commander, not only will their current life be physically terminated, but their next life—and every life after—will be arranged accordingly?”

Hiss—

...

”Hiss—ha!!—”

In the Administrative Center, under the gaze of countless onlookers,

Gudako’s soul was released back from the Underworld.

She took a deep breath and abruptly sat upright on the bed.

She looked at Setsuna, then at the surroundings—a circle of research lolis holding various instruments around her.

”I’m alive! I’m really alive!!!”

A group of little girls cheered excitedly as if witnessing a miracle, immediately surrounding her and running all kinds of scans.

Resurrection from the dead sounded like pure fantasy, yet in the Starsea Empire, all it required now was a quick word with the goddess of the Underworld.

”Mm-hmm. Your body is perfectly healthy. There’s no difference compared to your last physical examination.”

Kayo Senju looked at the results and nodded repeatedly.

”It seems this method of resurrection doesn’t cause any decline in bodily functions. It’s far more advanced than the revival scrolls provided by the Magic Academy.”

”Mm...”

Gudako glanced down at herself. The wound in her chest where the spear had pierced her was still faintly visible, rapidly healing under the effect of resurrection.

”Amazing. So amazing.”

Shua—

Ereshkigal’s projection appeared.

”I should remind you—while I can release your soul from the Underworld, another condition for resurrection is that your body must remain intact.”

”If you were buried or cremated, then even if your soul is released back to the world of the living, you wouldn’t be able to revive.”

”That’s easy.”

Several members of the Life Sciences Division patted their chests confidently.

”Reconstructing a physical body is effortless for us. We store the genetic data of everyone in the Starsea Empire. We can perfectly replicate a one-to-one body.”

”Once the body is ready, just release the soul back into it.”

”...Impressive.”

Kanae and Akame, watching from the side along with other ordinary people, felt as though they had stepped through the gates of a new era.

The Life Sciences Division reshaped the body. The goddess of the Underworld governed the soul.

From that moment on, immortality had been achieved on another level.

It was a great victory born from the fusion of science and magic.

”Mm... This feels like another technological revolution, doesn’t it?”

The crowd was stirred with excitement.

Thus, the Starsea Empire had overturned the conventional meaning of life and death, gaining control over death and reincarnation.

Then, a few days later.

Inside the Administrative Center, Yat Sen placed a personnel list in front of Setsuna.

”Reporting to the Commander, this is the recent casualty list.”

”Yesterday, during a high-energy physics experiment, two research teams were caught in a gamma storm due to close-range observation and were killed.”

”Another exploration team crossed the event horizon of a black hole while studying a singularity, and their shuttle was torn apart by gravitational forces.”

”Someone from the Life Sciences Division attempted to test a new neurotoxin on themselves and accidentally poisoned themselves to death.”

”Another person tried consuming unprocessed monster meat, claiming to be researching toxicity. They also poisoned themselves to death.”

The list contained a long string of names—all members of the Empire’s Research Division.

”Of course, all deceased personnel have already been received by Ereshkigal. Some have already returned to the Starsea Empire.”

”The rest had their bodies completely destroyed. The Life Sciences Division is currently creating new bodies for them.”

”???”

Setsuna felt a headache coming on as he read the report.

”Wait. Why are people suddenly dying?! I remember that since bringing them back, even if they got injured during experiments, we’ve never had casualties on this scale!”

”Uh... Perhaps because the Underworld now provides a safety net, the Research Division has become much more aggressive?”

Yat Sen spread her hands.

”Previously, for safety reasons, many dangerous experiments were observed by robots.”

”After the Underworld was established, the Research Division felt it was fine to take risks for first-hand, direct data. Even if they accidentally died, they could treat it as an Underworld field study. Either way, they wouldn’t lose out.”

”So this is the result. Oh, and Kayo Senju is currently having tea with Ereshkigal in the Underworld.”

”...”

Setsuna was speechless.

Yat Sen opened a communication channel and connected to the Underworld.

In Ereshkigal’s private garden, a group of little girls sat in a sea of flowers with the goddess of the Underworld, leisurely eating snacks.

”So this is what dying feels like... This Underworld is amazing! It’s just like the Commander’s private resort planet!”

”Right?! Only you get to be personally received by me. Ordinary souls in the future will just play with ghost generals and spirit soldiers up above.”

Surrounded by the little girls, Ereshkigal was in high spirits, handing out snacks to each of them.

The Underworld hadn’t had visitors this lively and adorable in a long time.

”Ereshkigal Onee-chan, can we do some field research in the Underworld while we’re here?”

”Can you tell us about the authority of the goddess of the Underworld? How do you control souls?”

”Also, how does the reincarnation mechanism operate? Can it cross species? Uh—n-no, I’m not planning to try that...”

Faced with the chattering children, Ereshkigal patiently answered each question with a smile.

”Don’t rush, don’t rush. Once your new bodies are ready, I’ll send your souls back.”

Upon seeing Setsuna, she waved enthusiastically.

”Master, come visit sometime too!”

”Uh—but come down the normal way. Your soul is too strong. It might not fall under my jurisdiction, so don’t casually end yourself!”

”...”

Setsuna pressed a hand to his forehead.

Those engaged in advanced scientific research inevitably carried a certain fervor incomprehensible to ordinary people—even if they were little girls.

”Even though the Underworld means we no longer have to worry about accidents, I still hope you’ll cherish your lives a little more?!...”

...

”Commander—”

”Build me a Heaven too!!!—”

After entrusting the Underworld entirely to Ereshkigal’s development, Setsuna had barely returned to the Administrative Center when a certain airheaded goddess with aqua-blue hair burst in, clinging to his arm with teary eyes.

”Commander, the goddess of the Underworld has her own Underworld now. I’m the goddess of Heaven! Shouldn’t I get a Heaven too?!”

Aqua circled around Setsuna like a dog begging for treats.

”We’re both goddesses. Commander, you have to treat us equally...”

Pfft—

Setsuna pinched her cheek.

”Ereshkigal needs the Underworld to restore her power and govern reincarnation. What do you need a Heaven for?”

”If it’s faith you want, there are plenty of Axis followers across the universes. You’re already much stronger than before.”

”That’s different!”

Aqua puffed out her cheeks.

”A goddess should live in the sky! When I was in Heaven before, I even had my own room!”

”I can manage reincarnation and transmigration too! Like sending people from one world to another, giving them cheat abilities, having them challenge Demon Kings and save the world...”

Bonk—

Setsuna flicked her forehead.

”Which world in the Starsea Empire needs you to save it? Wait... Wasn’t the Demon King in that world created because of you in the first place?!”

”Eeeeh—”

Aqua clung to Setsuna’s leg, sobbing dramatically.

”Commander, you’re biased!!!—”

”Is she really a goddess...?”

The onlookers were speechless.

”...Go back and properly manage your church.”

Setsuna lifted Aqua up.

If Eris had asked for a new Heaven, he would have agreed without hesitation. As for this one... better not.

”If, within the next year, the Starsea Empire receives zero complaints related to the Axis Church, I’ll agree to build you a new Heaven.”

”Otherwise, forget it.”

”Really?”

Aqua’s eyes lit up.

”Mm.”

Setsuna nodded.

”Friendly reminder—last year we received over a thousand complaints about Axis followers, including but not limited to harassing Eris believers, spreading rumors about Eris herself, and aggressively proselytizing.”

”As a goddess of Heaven, you need to restrain both yourself and your followers. Oh, and if Eris achieves this goal first, I’ll build her Heaven first.”

”Eeh—”

Aqua was shocked.

In her heart, she could lose to anyone—but not to Eris.

”Those aren’t rumors! Eris pads her chest!!!”

”I know. Personal attacks aren’t allowed either.”

Setsuna cleared his throat.

”You know? How would you know?...”

”Eris actually feels pretty nice. Soft and cute.”

”???”

Aqua didn’t fully understand, but she happily agreed anyway.

She soon returned to the Axis Church in the capital, rallying her followers and proclaiming her grand plan to build a Heaven.

”...Such an easy-to-handle goddess.”

Gudako smacked her lips.

She thought it was incredibly impressive to manage a group of goddesses so obediently. After all, in the human world, secular power and religious authority had fought for centuries.

”Whew—”

After sending Aqua away, Setsuna let out a sigh of relief.

Leaning back in his chair, he sipped some tea and teased a small shipgirl nearby.

”Who would’ve thought the first application of miniature universe technology would be creating an Underworld and a Heaven...”

Belfast casually remarked.

Even she hadn’t expected the technology acquired from the Three-Body universe to be used in such a peculiar direction.

”Mm...”

Setsuna tapped the table lightly.

”A miniature universe is a typical late-stage technology. The scale of the civilization and its productivity determine how large a miniature universe can be created.”

”Come to think of it... besides creating an Underworld and a Heaven, I have another bold idea.”

—

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