Imperium of Man Terra Aeterna Season 01: Rise of Humanity's War Machin

In the distance, vast fertile plains shimmered under the sunlight.

A tiny yellow chicken—a Manjuu—was enthusiastically driving a specialized tractor, plowing farmland with gusto. Some were busy scattering seeds, while others managed miniature automatic irrigation systems that looked like toys, yet functioned with military-grade efficiency.

Closer to the port area, several Manjuus could be seen neatly transporting supplies. Some drove specialized container trucks, hauling heavy loads toward a city center still under construction. They looked like fluffy dumplings—far too adorable for such heavy-duty tasks.

Kanae could only stand there, stunned, feeling as if she were walking through a dream.

If the outside world had reached a stage where all labor was performed by robots, she could have understood.

But this… this made no sense.

In the Imperium of Man, artificial intelligence (AI) was a taboo. The only exceptions were the Red Queen and White Queen—two superior AI systems possessed solely by Reuel.

Beyond that, the Imperium's entire technological foundation relied on Machine Spirits, the sacred techno-rituals of the Mechanicus, and Servitors—biotechnological cyborgs formed from a fusion of human bodies and machines.

So what the hell is this tiny yellow chicken?!

And that little lolita surfing on the waves?!

And those Bulins wielding wrenches bigger than themselves, building giant robots like it's child's play?!

This world truly couldn't be defined by military logic—let alone scientific reasoning.

"This is the world of magical girls—and also, my world."

Reuel greeted the ship girls with a calm smile and invited the three Butterfly sisters to look around.

At first, they were nervous—especially when a few members of the expedition team suddenly appeared through a portal, causing parts of the ship's armor to peel off from dimensional resonance misalignment.

The trauma from the incident where a ship girl dropped a nuclear bomb on Muzan Kibutsuji's body still haunted their minds.

But gradually, the three began to relax.

The ship girls had warm and caring personalities. They introduced various aspects of life in Terra Aeterna with infectious enthusiasm.

"This is our main naval base. Usually all ship girls are stationed here,"

said Yukikaze, who looked like a little girl with animal ears, cheerfully wagging her tail.

"If you've got time, come hang out with us!"

She led the tour with a laid-back attitude, making the atmosphere feel much lighter.

"At first I was really curious about that breathing technique. But when I tried it... well, it didn't work."

"What? But breathing techniques can significantly strengthen the body!"

Shinobu stared at Yukikaze in disbelief.

"Which one did you try?"

"Breath of the Sun, I think. Commander brought it over from your world, right?"

Yukikaze scratched her head awkwardly.

"But... Akashi said if I wanna get stronger, it's easier to just install a new reactor than worry about breathing patterns and foot positions."

"A reactor...?"

Kanae fell silent. That sentence sounded like it came from another dimension entirely.

The three of them truly couldn't keep up with this world's logic.

"Now, up ahead is the main fleet port. On the left is Sister Enterprise, right is Sister Yat Set, and in the middle—the biggest one—that's Sister Musashi."

"If you want to board any of the ships, I'll need to get permission first. Other than the Commander and Bulin, outsiders aren't allowed to step on their decks."

Yukikaze then lowered her voice slightly, her expression turning more serious.

"But don't go near that other area across the bay. There's a group there... kinda creepy."

"They wear red robes, covered in skull accessories. If you see them, stay away. Don't ask why."

The three girls looked at each other, baffled.

"…?????"

They continued walking, following the edge of the Golden Horn, surrounded by warm fjords bathed in the glow of twilight. Yukikaze, the animal-eared ship girl, extended her hand, inviting the three to come closer.

At the fjord port, several aircraft carriers were undergoing routine maintenance.

Their steel hulls were partially opened, revealing intricate internal mechanisms.

The technicians—a combination of ship girls, Manjuus, and Bulins—moved swiftly, carrying heavy equipment with practiced ease.

On deck, some soldiers were drilling in formation while tiny aircraft darted through the air, narrowly avoiding midair collisions.

"Are these… aircraft carriers?"

The Butterfly Sisters were stunned.

Up close, they could truly grasp the sheer scale of this fleet.

They had seen the armored ships of the United Fleet before, but compared to these carriers, those seemed like children's toys.

And above them—hovering gracefully in the sky—was a Gorgon-class battlecruiser, far larger than all the carriers combined.

"You… you're truly amazing,"

Kanae said, her voice filled with genuine awe.

To anyone from an industrial-age world, the sight of a navy that blended modern and space-age technology was nothing short of miraculous.

But then, Shinobu noticed something.

"But… there aren't that many of you, are there?"

The city around them was vast—perhaps many times the size of Kyoto—with architecture more majestic, on a planetary scale.

Yet only a few ship girls could be seen, along with some Manjuus and Bulins.

There was none of the usual bustle one would expect from such a massive settlement.

"This place is still new,"

Reuel explained.

"We're rebuilding this world from scratch. The population is still small."

He continued casually.

"But once the large-scale Bulin creation program begins, the population will grow rapidly—tens of thousands, maybe hundreds of thousands."

Then, with a calm gaze, he turned to the three girls.

"So... what do you plan to do next?"

The three fell silent.

With Muzan destroyed, the Demon Slayer Corps had lost its reason for being. Their main purpose had been fulfilled.

Now, their world no longer needed demon hunters.

"Maybe… go back to the village and farm with the townspeople?"

Kanae said softly, unable to hide the note of loss in her voice.

Reuel gave a small smile.

"In that case, why not just stay here?"

"My house is still empty. Food, supplies, daily needs—those won't be a problem."

"And if someday you decide to return home, Ninghai and Pinghai can escort you. They make interdimensional trips now and then."

The three looked surprised. The offer sounded almost too easy—perhaps too smooth.

"Eh? Are we… allowed to?"

"Of course. This place isn't crowded yet, so we can adapt easily."

Yukikaze gave a little hop of joy, affirming the idea in her typically Yukikaze way.

"But… is there anything we can do here?"

"Do you need demon slayers, or guards, or something?"

Reuel only laughed lightly.

"No need. This world is peaceful. The ship girls are already protecting the capital."

"Then… what can we do?"

"That's up to you. Here, everyone does what they can—and receives what they need."

Shinobu, who had been quietly deep in thought, finally raised her hand gently.

"I know a bit about medicine… though it's mostly herbal treatment."

"Excellent," Reuel nodded.

"We don't have a civilian doctor yet. Start with medical school. I'll get you books on modern medicine."

"Once you've mastered the basics, I'll raise the level of difficulty."

Shinobu nodded. A small light began to grow within her.

Kanae and Kanao, on the other hand, looked hesitant.

"We… don't really know what we can do here."

"You can help Ninghai and Pinghai manage affairs between the two worlds,"

Reuel said with a smile.

"And learn some administrative work along the way. You already understand the Demon Slayer world well—that'll be valuable."

At last, the two nodded slowly.

"By the way," Reuel said, now with a slightly more serious tone,

"You are the first humans from another universe to choose to live here."

A gentle wind blew in from the fjord, carrying the scent of metal and sea, and a faint hope on the horizon.

This world was strange, filled with contradictions… yet somehow, it felt like a new home.