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

Swish—a familiar sound echoed as the fabric of space and time parted, opening a shimmering webway gateway.

Reuel and his group stepped back into the world of Resident Evil, specifically in the region that had now become the capital of the Imperium of Man, currently undergoing massive development.

A vast blue sky stretched above, the crystal-clear ocean reflected the sunlight, and a soft breeze swept gently through the air. Unfortunately, the natural beauty was slightly marred by the colossal construction of the Imperial Palace—spanning from Europe, across Asia, the Middle East, and into Africa.

Even so, despite the scale of this megaproject being far from completion, the air quality in Terra Aeterna: Resident Evil remained several notches above the atmosphere of the Kimetsu no Yaiba universe—an irony, considering environmental awareness was almost nonexistent in the current construction priorities.

It was already midday. Most likely, everyone was still busy with their work.

"We've been there for over a month. I wonder if everyone here is doing okay?"

"How has Yat Set been managing this place? He shouldn't have any issues… I mean, nobody's crazy enough to attack the Imperium of Man—except the Xenos."

Reuel was piecing together his thoughts, not yet finishing his contemplation when—

"Hi~ Commander, you're back!"

Suddenly, a cheerful voice rang out from above—a lively, energetic little girl's voice.

When Reuel looked up, his eyes immediately caught a familiar sight: a tiny ship girl with silver hair and animal ears, floating freely in the air like a rocket pilot.

A large jetpack was strapped to her back, blasting plasma downward, keeping her suspended dozens of meters above sea level.

"Yukikaze?!"

"How the hell are you flying?!"

The five adult ship girls who were with him stared upward in shock.

Meanwhile, Ursarkar E. Creed and the Cadia Shock Troopers were still in the Kimetsu no Yaiba universe, awaiting the arrival of the planetary governor and other delegates.

"Didn't the Commander give Akashi and Minato access to technology from the Gundam universe? Including tech from the Imperium of Man?"

"When we built the Gundam, we took the chance to study its internals. Some components were hard to replicate, sure, but the space thrusters and energy weapons… were insanely cool!"

"While you and the other big sisters were away in the Kimetsu no Yaiba world, we had nothing to do. So yeah, we used the time to install new gear. Super fun, Commander! Nanoda!"

Yukikaze adjusted her jetpack and landed softly in front of them, exuding the boundless energy of a child.

Reuel recalled something—after he sent technology to the Minato port region, the Azur Lane world went absolutely haywire.

The ship girls had gone into an experimental frenzy, and the result: endless daily chaos for the poor wide-eyed Sirens. The girls tried mounting Gundam thrusters onto their own bodies, hoping to perform aerial maneuvers like real fighter jets.

Unfortunately, the early attempts… were kind of pathetic.

Their first propellers looked more like abstract art—or more accurately, like Doraemon's bamboo copter. Max altitude? Barely ten meters. And that was considered a success. Most test flights ended in crashes, splashdowns, and propellers shattered into pieces.

But now, the latest versions they were using had improved dramatically.

Not only were they smaller and lighter, they also had insane thrust capacity. The tech could even launch a destroyer-class shipgirl weighing several thousand tons into the sky with little resistance.

"So… all of you can fly now?"

Richelieu looked at them with a near-disbelieving expression.

"Of course not!"

Yukikaze put her tiny hands on her hips, chin lifted proudly.

"Only us—destroyer-class ships! You Aircraft Carrier and Battleship big sisters are too heavy!"

Without waiting for further reaction, Yukikaze reactivated her jetpack and blasted into the air. The fiery trail from her thrusters drew a cat-shaped pattern in the blue sky—a show of skill and pride she had never experienced before.

All this time, the loli-class Destroyer shipgirls had always felt inferior to the heavy firepower of Heavy and Large Cruisers. But now… for the first time, they had something the "big sisters" didn't.

Reuel looked toward the sea, his eyes catching a striking scene.

Dozens of loli-class Destroyer shipgirls floated in the air, each equipped with jetpacks, maneuvering above the ocean surface. They could even manifest their combat uniforms while airborne.

Some launched simulated naval artillery strikes toward land, demonstrating cross-domain amphibious combat capability—sea, land, and air.

Below them, the battleships and aircraft carriers could only watch in silent envy.

"….."

"….."

Reuel let out a quiet sigh. He had to admit, military-industrial advancement had made a huge—and rapid—impact. It hadn't taken long after Gundam technology was distributed for Azur Lane's engineering sector to leap far ahead, combining their own weapon systems with designs and tech from other worlds.

Still, Reuel couldn't suppress a frustrated mutter in the back of his mind.

"So this is… a castrated version of a Gundam pilot? A shipgirl pilot?"

"And why... why the hell did Azur Lane's spies manage to steal access to the Gundam world's Combat Lab...?"

He let out a long sigh. His head throbbed.

After a brief pause, Reuel looked up at the sky now filled with streaks of light from the jet trails of the flying loli Destroyers. He could only hope that their next experiment wouldn't result in... something even crazier.

The shipgirls soon noticed the returning expedition team and greeted them with enthusiastic cheers, excitedly asking about their mission.

The loli shipgirls who hadn't joined the expedition quickly swarmed some of the team members, tugging at their hands and begging with curiosity—eager to hear tales about the Oni demons that nearly destroyed the world.

Stories flowed like water—from Richelieu's holy cannon turning a child-grinding factory into ash, to airstrikes on inhuman armies, and the "Black Ship" incident that sparked the birth of a new civilization and world conquest.

Hearing all this excitement from their comrades, some loli shipgirls grew even more pumped up.

"Wow! That spotlight is so unfair! Commander, I have to join the next expedition!!"

"I could totally take on the entire Royal Navy fleet by myself, y'know?!"

Loud complaints echoed around Reuel. The loli Destroyers crowded around, grumbling and pleading not to be left behind again. Reuel chuckled softly and comforted them one by one, promising they would get their turn next time.

"Alright," he finally said, "it's time for a battle summary."

The vanguard fleet commanders gathered. Every shipgirl combat mission required a post-op report: consumed supplies, acquired assets, and whether strategic objectives were achieved.

The Kimetsu no Yaiba expedition was no exception.

"The tech level there is low," Reuel began, placing several items on the table. "There's no structured magic system or supernatural powers worth deeper study. But the breathing techniques and Oni demon records—those are interesting enough."

He pointed to two books and two blood vials filled with thick red fluid.

"This is ancestral Oni blood, and these two are manuals—one for breathing techniques, the other for demon arts. Hand them over to Akashi and the tech-priests for further analysis."

Yukikaze, with her childlike curiosity, flipped through the breathing technique book with an eager face.

"Breathing arts and sword techniques? Whoa, can I learn them too?!"

"….."

"….."

Reuel held back a smile.

"You can study it if you really want to, but I don't think… it's all that useful for you."

He explained, "These techniques are meant to enhance the physical capabilities of humans. But you—although amazing and adorable—aren't human, Yukikaze. You're a technological creation, and your combat prowess relies on mechanical upgrades, not physical training."

"Wouldn't it be better to focus on propulsion system upgrades or space weapon enhancements?"

Yukikaze pouted, lips sticking out in a slight sulk.

"Heh, like I'd ever trade away a warship hull. Those things can't even fly like I can!"

She spun mid-air, slightly irritated but still proud.

"Besides," she added with a confident nod, "our greatest victory is... that we conquered that universe!"

"From now on, the Kimetsu no Yaiba universe is officially one of our primary resource zones. We can produce raw materials there and channel them into Minato and Terra Aeterna."

Reuel arranged several diplomatic documents on the table—all signed by local powers from that world.

Ning Hai tilted her head, a doubtful expression on her face.

"Hmm... hearing it like that, it kinda sounds like... we're the bad guys?"

Reuel just smiled.

"I actually wanted to build peaceful cooperation. But the problem is, there was no global governing structure to negotiate with. Even if I chose to support a specific faction, like the Republic of China... who's to say they'd last long?"

He shrugged.

"Dealing with capitalists is more exhausting than war. They're cunning, full of hidden agendas, and constantly backstabbing each other."

"So the most efficient solution: wipe them all out quickly and build a new system from scratch."

Reuel wasn't fantasizing like some war-crazed maniac. He was just being realistic—back in 1912, even Earth itself stood on the brink of World War I. Chaos everywhere. Sometimes, fast and brutal solutions were necessary to establish long-term order.

Destroy, then rebuild. Reshape the world from the ground up.

Ping Hai, who had been quietly listening the entire time, finally spoke.

"So we just wait for them to pay tribute every month? Send someone to collect the raw materials, then we're done?"

"Hmm, more or less," said Reuel with a nod. "But before that... there's something else we need to do."

He looked at the large map projected on the holo-display.

"We need to initiate sustainable fishing operations. First, to preserve the ecosystem. Second... we can harvest all the fish from their lakes."

---

Throughout history, two main models have existed for managing tribute-paying states or colonies.

The first was brutal, resembling the plunderers of the Age of Exploration: utterly strip-mining conquered territories, seizing every resource with no mercy, then vanishing before the locals could fight back.

This method was effective in the short term, but too harsh, uncivilized, and clearly unsustainable.

Entering the colonial era, industrial powers like Britain and France began acting more "civilized" while exploiting underdeveloped agrarian nations.

Rather than total destruction, they ensured the local populations lived just enough to be exploited for longer periods—raiding minerals, spices, food, and other resources while constructing infrastructure that strategically benefited the colonizers.

With this approach, native resistance was typically weaker, and all parties could "survive"—at least on the conquerors' official records.

But Reuel's idea went far beyond either model.

---

"Ning Hai, Ping Hai," said Reuel as he unfolded a world map. "From now on, in addition to farming, you two will also handle administrative affairs in the Kimetsu no Yaiba universe. Just temporarily, until a permanent planetary governor is appointed."

The two ship girls exchanged confused glances.

"I'll explain the development plan. Just follow it."

Reuel began pointing at several spots on the map. "First, we need to push their world into the industrial era. Priority goes to agrarian nations in Asia and Africa that are still lagging behind."

"Send tractors, harvesters, and other agricultural tools. Teach them modern production techniques. The industrial nations can manufacture fertilizers and equipment, then distribute them in a coordinated fashion."

"After that, build a railway network between cities and across continents. Logistics infrastructure is non-negotiable."

"Electricity must be available everywhere. If necessary, call in the universal bulins and tech-priests from Mars. They can build a power distribution network in a matter of days."

Reuel folded his arms. "That kind of job is nothing for them. No need to deploy large workforces."

He continued without pause.

"Once the foundation of industrialization is laid, build an education system. I'll send the appropriate personnel later. And if everything goes well, the next phase will be transitioning to the space age."

"Don't forget healthcare. Teach them to boil water, and ask Minato to develop basic vaccines—penicillin, malaria, and so on…"

"…???"

Ning Hai and Ping Hai stared at Reuel like they had just seen an alien crawl out of a wormhole.

"Commander... are you doing charity work?" Ping Hai asked hesitantly. "I thought you were just going to rob them blind…"

Reuel's recent behavior seemed far removed from his usual 'smash every planet and conquer the world through intimidation' approach.

Reuel chuckled softly. "The purpose of the beatdown is stability. So they're not tempted to start a resistance movement later."

"Hit them with a stick first, then give them dates," he said lightly. "If you want to rule the world, you can't rely on military strength alone. You have to make them grateful for your rule."

He concluded seriously, "And remember this well—we're not trying to build a predatory colony. We want sustainable development in the Kimetsu no Yaiba universe."

"The beatdown is for easier management," Reuel added casually. "So no one gets sweet-talked by outsiders or secretly stirs up trouble later."

He smiled faintly, eyes fixed on the map as if he already knew how this game ended.

"If you hit me with a stick," he continued, "I'll give you dates. To rule the world, brute force alone isn't enough. You need narrative, prosperity, and… a system."

He leaned forward. "And let me emphasize once more: sustainable development in the Kimetsu no Yaiba universe is the foundation of our Imperium."

---

At the start of 1912 on Earth, major powers like Britain, the United States, and France had already completed their industrialization.

Other nations, including the Russian Empire under the Tsar, still staggered between semi-agrarian and semi-industrial stages.

In other parts of the world—in Asia, Africa, and Latin America—many backward agrarian regions still existed, some even home to primitive tribes.

From such places, it was nearly impossible to extract wealth directly.

The solution? Don't plunder. Uplift them.

"No way they can leap straight to the space age," Reuel muttered as he studied the development charts. "They're not ready."

The children of Kimetsu no Yaiba currently studying at the Schola Progenium will become the new generation of the Imperium of Man.

They are the future. They are the foundation that will support our civilization.

With rising productivity, agricultural and industrial output will soar.

And when that happens, Reuel will be able to extract resources from the Kimetsu no Yaiba planet and other worlds within the colonial network.

Like a cake that gets bigger, everyone gets a larger slice.

As the civilian population's standard of living rises, not only will they stop complaining—they'll be grateful.

They'll worship the Imperium of Man, praise the soldiers who brought electricity, penicillin, chemical fertilizers, and education to their world.

The Kimetsu no Yaiba World will transform into a stable strategic headquarters—a regional power center within the Imperium of Man.

A win for everyone. One might even call it a tier-three victory—beyond predatory colonization.

"Let the old folks die off naturally," Reuel said flatly. "And their children will grow into the foundation of our future power."

"Whoa… that's complicated…" Ning Hai murmured.

"Let's go back and think this through…" Ping Hai echoed in confusion.

The two ship girls looked dazed after receiving stacks of strategy documents from Reuel.

They left, hoping a planetary governor would be appointed soon.

They were built for war, not managing multigalactic bureaucracy.

---

After completing the advanced setup, Reuel returned to the command center and reviewed the progress of the Imperial Palace construction over the past month.

Most of the construction projects in Terra Aeterna's capital had shown solid foundations.

Industrial zones on various colony planets had begun production, and civilian settlements as well as administrative centers had been completed in nearly every major colony.

However, the current population size was still insignificant compared to the Imperium of Man from the original Warhammer universe.

Even when counting the Bulins, Manjuu, and newborns, the total population of Reuel's Imperium barely reached 7 trillion.

A figure far below the scale of the original Imperium, which spanned millions of planets.

These people were spread across various colonial planets, leaving the capital Terra Aeterna feeling empty.

At its heart, inside the colossal Imperial Palace covering 92.39 million square kilometers, the buildings stood grand yet hollow.

Only the Tech-Priests of the Mechanicus, Manjuu, shipgirls, and Imperial Guard forces patrolled the area.

Even little yellow chickens like the Manjuu could afford duplex villas here—though they preferred sleeping in the small shacks they had built themselves.

At Minato Port in the Azur Lane universe, constant activity roared day and night.

Experiments on new weapons were carried out non-stop, with shipgirl pilot teams deployed daily to sweep surrounding seas—and of course, to provoke the Sirens: big-eyed alien creatures far too cute to be taken seriously, yet far too dangerous to be ignored.

Unfortunately for the Sirens, their naval weaponry couldn't reach the skies. Meanwhile, their anti-aircraft firepower and jet units couldn't breach the defensive shields of the shipgirls.

Over the past few weeks, Minato Port's operational area had expanded significantly.

They were growing more aggressive—and more curious.

The current focus was on developing advanced weapons that were lightweight and mobile, yet strong enough to take down high-class Sirens.

In general, both sides were experiencing rapid technological advancement. But the introduction of materials from the Demon Slayer universe had changed the game.

With that world now serving as a logistical base, Minato Port was no longer suffering from supply shortages.

For Reuel, the road to building a true Imperium of Man—as in original Warhammer 40K lore—was still very long.

In his source universe, the Imperium could wage war against Xenos, heretics, traitors, alien monstrosities, even the Chaos Gods themselves.

All of that was powered by a population so massive, it would seem absurd if brought into the real world.

---

Reuel let out a deep sigh, deciding to stop meddling too much in the Imperium's administrative affairs. He had other priorities now.

Besides, the women of Terra Aeterna's Resident Evil Branch could handle it.

Although… the last time he visited them, things had been a little tense.

"Could they still be sulking because I brought too many Lolis and Universal Bulins with me?"

Reuel scratched his head, half worried, half amused.

He was known as an eccentric leader—but that didn't help much when facing the piercing gazes of formidable women like Jill, Ada, and Claire.

Reuel promised himself he'd visit them again once the Imperial Palace construction was stable enough.

But suddenly, like a bolt of lightning on a clear day, a thought smacked him in the brain:

"Wait… where the hell is my Gundam?"

Before he departed for the Demon Slayer world, Akashi had been busy designing a personal Gundam unit for him—complete with jetpack and energy weaponry.

But since then, Reuel hadn't heard a single word about its progress.

Without thinking twice, he strode quickly toward Akashi's workshop.

Bang! Bang! Bang!

The loud clang of metal being hammered echoed from behind the door.

Clearly, something was being processed—or perhaps assembled—inside.

Reuel knocked on the door, a little impatient.

"Hello? Akashi?!"

After a short pause, the door swung open with a bang, revealing a familiar figure: Akashi, the cat-eared shipgirl, grinning wide, her eyes squinting in gleeful excitement.

"Commander~! Welcome home, nya~~~!"

Akashi's trademark cheery voice greeted him like he was a regular customer at a souvenir shop—not the supreme leader of a galactic Imperium.

"Come take a look at your war machine, nya~! But remember, payment's not done yet, nya!"

Reuel sighed, already guessing that Akashi's invoice would be longer than the heresy scrolls of Warhammer's most damned traitors.