Crossover Shipgirls: Building a Dimensional Empire from Scratch

[System binding in progress… Assisting host with reincarnation…]

[Searching for a suitable universe…]

[Loading language module…]

[Error!]

[Warning! Timeline distortion detected during traversal… No human civilization detected. Attempting to fix… Correction failed…]

[Activating fallback protocol. Compensatory measures being constructed… Confirmation in progress…]

[Compensation complete!]

"Cough, cough…"

"Ugh…"

In a modestly designed wooden house, Setsuna opened his eyes and rubbed his head.

Struggling, he sat up from the bed.

The room's furnishings were unfamiliar.

The 50-square-meter space contained a bed, a dining table, a few chairs, and a large chest piled in the corner.

Everything was wooden, resembling a dwelling of medieval peasants.

"Did I… transmigrate?"

After looking around for a while, Setsuna reluctantly pieced things together.

Not long ago, he was just an ordinary office worker on Earth who had been hit by a dump truck while commuting.

At that pivotal moment, a system had asked if he had any specific wishes for his upcoming reincarnation.

He had casually made a few requests:

• "The new world shouldn't be too boring—make it exciting, with the occasional surprise, but not too dangerous. None of that Lovecraftian horror or SCP nonsense…"

• "Also, I'd like my cheat abilities to have great growth potential—preferably powerful enough to reach universal or multiverse levels in the future…"

The system seemed accommodating and had agreed to his requests.

So, he had eagerly anticipated seeing what kind of world awaited him.

"Where am I?"

Setsuna asked.

[The future, Earth in the year 2260.]

A cold, mechanical voice replied.

"Huh?"

Setsuna was startled.

"Does humanity in the 23rd century live in wooden houses?"

"This isn't what I imagined!"

Sitting up, he examined his surroundings again.

There were no electronic devices, nor anything that could be remotely associated with advanced technology.

The large chest in the corner contained rice, flour, dehydrated vegetables, purified water, some seeds, and medical supplies.

It felt less like the 23rd century and more like the 13th century.

Opening the door, a chilly wind blew in.

The world outside was eerily silent, devoid of any signs of human activity.

Broken remnants of buildings lay scattered nearby and in the distance, long past the point of recognition.

Plants had overtaken the cityscape, ash floated through the air, and the entire scene reeked of an apocalyptic wasteland.

"What's going on? World War III?"

Squinting, he peered into the distance.

Judging by the surviving architectural styles, he guessed he was on the outskirts of a European city.

[This timeline's human civilization went extinct thirty years ago.]

[Confirmed: Apart from you, there are no human survivors on this planet.]

The system responded.

"What?!"

A string of question marks hovered over Setsuna's head.

This was not a surprise—it was a shock.

[Apologies. An unknown bug occurred during traversal, leading to a timeline error.]

[Humanity in this timeline is extinct. As a result, your 'Stellar Conquest' system could not be loaded. As compensation, the 'Dimensional Civilization' system has been activated instead, significantly enhancing your mental strength and physical compatibility.]

The cold mechanical voice echoed in his mind.

"Wait a second."

Setsuna was shaken.

"Humanity is completely gone?!"

"And what's this 'Dimensional Civilization System'? What does it even do?"

[This system will assist the host in rebuilding a hyperdimensional civilization from scratch, spanning multiple universes.]

[The host can freely traverse other worlds, recruit companions, earn rewards, and establish a civilization that dominates the multiverse.]

"…"

"Fine."

Setsuna sighed. He wasn't entirely surprised.

As humanity's sole survivor, starting from scratch to rebuild civilization was, in a way, a grand endeavor.

Shaking his head, he opened the system's statistics panel.

[Civilization Overview]

• Civilization Type: Technological Civilization

• Technological Level: Stone Age

• Population: 1

• Species: Human

• Territory: 60 square meters of surface area

The 60 square meters, apparently, referred to his wooden cabin.

As for the civilization type, it seemed the world's civilizations could generally be categorized into technological or magical.

Conventional human civilizations, like the Trisolarans, Cybertronians, or Stellaris empires, fell under technological civilizations.

Fantasy worlds with magical girls, Teyvat, or Chaldea, while occasionally incorporating technological elements, predominantly relied on magic.

Of course, hybrid civilizations existed as well.

But he soon noticed a glaring issue.

"My civilization is at the Stone Age? Does this make me a caveman?!"

"Come on, I have a college degree, for crying out loud!"

Setsuna felt that the system's assessment was deeply flawed.

[The level of a civilization is determined by the technologies it masters and the tools it can create.]

[Although you come from a pre-spacefaring civilization, you must now start from zero.]

The system replied.

[Stone Age humans already mastered techniques for polishing stone tools, making pottery, and basic agriculture and animal husbandry.]

[Since you consider yourself modern, let me ask: Do you understand high-energy physics or astrophysics?]

"No, I majored in civil engineering."

Setsuna shook his head.

[Do you know organic chemistry or automation?]

"No."

[Can you build a steam engine?]

"No materials for it."

[Do you know animal husbandry?]

"Uh… does walking dogs and petting cats count?"

[It does not. By our classification standards, you are indeed at the Stone Age. Please work hard to advance your technology.]

"Damn."

Setsuna found the reasoning frustratingly hard to refute.

Starting from the Stone Age, with nothing but the clothes on his back.

It took Setsuna only a few minutes to understand his situation.

What's the most important thing when starting a civilization from scratch?

First, build a town center, then produce workers to chop wood and mine ore… Wait, no, that's not right.

Chop down a tree and craft a workbench… No, not that either.

Deploy a base car, build a power plant, then a barracks, and send dogs to scout… Ahem, wrong again.

Obviously, the first thing is to check for cheats!

This lousy system had thrown him into a primitive world, so he needed to figure out what this Dimensional Civilization System was all about.

"Hello? Hey?"

"Is there a tutorial or maybe an introductory quest?"

Setsuna asked aloud.

[Dimensional Civilization System Activated]

[Initializing quest...]

[Initial Quest:]

• [Establish a civilization and increase the population of your settlement to over 20 individuals.]

• [Reward: Initial Technology Tree ×1]

"…"

Setsuna stared at the task panel, lost in thought.

"Recruit 20 people? Am I supposed to reproduce by mitosis?!"

"And can you explain what this reward means? What is an 'Initial Technology Tree' supposed to be?"

[Every civilization in the vast multiverse has its unique technology tree. Completing the quest will grant the host the technology tree of one world, serving as your civilization's foundational tech.]

The system responded.

The explanation was a bit convoluted, but Setsuna managed to grasp the gist.

Different worlds had distinct technological paths.

For example, the Type-Moon Universe focused on magic, magecraft and Command Seals, the Honkai Universe revolved around Honkai energy, Teyvat thrived on elemental forces, and the Tengen Toppa Gurren Lagann Universe used spiral power as its core.

The quest reward would grant him the corresponding technology tree, effectively deciding the direction of his civilization's development.

Then, the system issued another prompt.

[Initial quest detected.]

[Host has been granted an initial ability: Dimensional Diplomacy.]

[Dimensional Diplomacy:]

[You can observe other civilizations in the vast multiverse, engage in diplomacy with them, and freely traverse their worlds.]

"?"

"What kind of ability is this?"

Setsuna was stunned for a moment.

Observing other civilizations? It sounded like some kind of vision-expansion skill.

Every world, when viewed from a higher-dimensional perspective, could be considered an independent civilization.

This authority would allow the host to engage in diplomacy and traverse the multiverse.

[Opening the Hyperdimensional Star Map...]

Following the prompt—

Swish!

His vision blurred.

In front of him, a radiant star map appeared, resembling the strategic maps seen in games.

Against the backdrop of the starry sky floated clusters of objects that looked like soap bubbles, each reflecting the shimmering light of the cosmos.

Each "bubble" represented the universe of a distinct world.

Looking closely, he noticed five "world bubbles" marked near his position.

• Demon Slayer: Steam Age

• Date A Live: Tier-II Magic Age

• Azur Lane: Pre-Space Age

• Fate/Grand Order: Tier-III Magic Age

• Honkai Impact 3rd: Pre-Space Age

Each world bubble was labeled with its name and technological age.

"A multiverse map?"

"Are these my neighbors?"

Setsuna studied the map, intrigued.

These were all different worlds, situated close together on the star map, much like countries on a geographical map.

Some were from anime, others from games.

Though they appeared close on the map, each world bubble was, in reality, a vast universe.

The system had essentially provided him with a higher-dimensional perspective, enabling him to observe the multiverse.

Additionally, the classification of technological levels for different civilizations was quite interesting.

There were three technological civilizations and two magical ones.

Both Azur Lane and Honkai Impact were in the Pre-Space Age.

While these worlds were home to powerful individuals and entities, neither possessed interstellar travel capabilities.

Demon Slayer was comparatively more primitive, stuck in the Steam Age.

As for Date A Live and the Type-Moon Universe, their civilizations leaned heavily on magic. Setsuna could only assume that the Type-Moon Universe's magical expertise was superior, considering its abundance of Lostbelts.

Interestingly, no matter how many parallel universes a specific world contained, the Hyperdimensional Star Map consolidated them into a single entity.

Further out, he could faintly discern other peculiar world bubbles like Heaven's Lost Property, Re:Zero, Neon Genesis Evangelion, and Nekopara…

However, his current mental strength wasn't sufficient to observe them clearly.

"This map… it's insanely high-end."

Casually selecting one of the worlds, detailed information immediately popped up:

[Demon Slayer: Steam Age]

• A world set in the Taisho-Era Japan, with a technological level in the mid-Steam Age. Steam engines and firearms are in moderate use.

• Features supernatural entities known as "Demons" that possess combat abilities far surpassing humans, but they also have notable weaknesses.

Comparison of Strengths:

• Technological Level: Like a God.

• Military Strength: Like a God.

• Economic Power: Like a God.

[Options:]

• Diplomacy

• Traversal

• Declare War

"…"

"Even a Steam Age civilization gets to ride on my head?!"

After surveying the surroundings, Setsuna found that all his neighbors were labeled as "Like a God."

Well, that wasn't surprising.

His colony consisted of just one person, with Stone Age-level technology—he couldn't exactly compete.

He examined the functionality of the three listed options:

Diplomacy: Initiate communication with a faction leader within the target world. If no leader exists, communication is unavailable.

Traversal: Open a dimensional portal to travel to the target world. The landing site is random.

Declare War: Unlocks after entering the Space Age.

"…"

The interface gave him a strong sense of déjà vu.

It reminded him of a certain game that involved biomass reactors, species extinction, neutron sweeps, turning aliens into canned food, and apocalyptic ascensions.

"…"

Narrowing his eyes, Setsuna muttered:

"Since the start, I've been meaning to ask—this system… you're a Paradox Interactive war criminal, aren't you?!"