Crossover Shipgirls: Building a Dimensional Empire from Scratch

Crack—

Setsuna stood opposite the remnants of Unicron, suspended in the starry void.

The once majestic and towering construct had been blasted into fragments. The surface of the metallic planet was covered in wounds carved by high-energy weapons.

Now, it could barely even be called a ”planet.” Nearly a quarter of its volume had been shaved away, leaving behind a grotesque and irregular shape.

Placed within the universe, it would easily remind one of a planetary-class warship destroyed in an interstellar battle.

Unicron’s status far exceeded that of any so-called planetary warship. It was the ”god” of this universe, a symbol of death, chaos, and destruction.

Destroying its material form did not mean destroying the very concept of destruction it embodied.

So what Setsuna was considering was something else entirely.

”Just dismantling a few parts to bring back for research would be a bit dull.”

”Since we’ve gone through all this trouble to get here, why not be bolder?”

A massive surge of Honkai energy poured from his hand into the remains of Unicron.

In the past, using the authority of the Herrscher of Corruption to erode Unicron was something Setsuna would not even have dared to dream of.

The difference in their existential ranks had been far too great. His power had not been enough.

But now, having fused the Suniaster, the powers of Outer Gods, and other forces—along with possessing a special weapon like the Allspark, uniquely effective in the Transformers universe—he felt it was worth trying.

No matter what kind of energy it was, he could convert it within his body into Honkai energy, then release it outward through the authority of the Herrscher of Corruption.

Shhh—

Unlike when he teased Senti or created Honkai Beasts—where he could subdue them in an instant—this time felt different.

He felt as though his corrosive energy had been poured into a boundless ocean.

More precisely, he was ”eroding” and ”polluting” the other party.

Unicron had only just descended from the Dead Universe. Its power was at its weakest, and it had just endured a brutal beating from the Starsea Empire.

This was the perfect moment to strike while it was vulnerable.

”Tsk... the Commander really dares to think big...”

The nanorobot put away the dismantling and surveying tools in its hands, signaling the engineering division to hold off for now.

”Hm?!”

Nyaruko, Kuuko, and a few other Cthulhu girls poked their heads out from the viewport, staring downward.

”What’s the Commander doing...?”

”He wants to erode that big guy in front of us and completely take control of Unicron.”

Grey shrugged.

”But it looks a bit difficult. Its physical form is weakened—because it hasn’t eaten its fill—but it’s still a bona fide god. It won’t go down that easily.”

”I’d guess the Commander will have to fight a tug-of-war for a while. Uh... he should have pretty good stamina, right? What do you think, Formidable?”

”...”

Formidable rolled her eyes. Only this one could slip in a dirty joke at any given moment.

Setsuna was indeed clashing with Unicron’s will.

Eyes closed, he guided the authority of the Herrscher of Corruption deeper into Unicron’s shell. The shattered outer metallic layer gradually became shrouded in black.

However, just as the corrosive force was about to reach the core, it met fierce resistance.

It was pure chaos energy, directly opposing the power of corrosion.

Like raging tides and thunder, it shattered the invading Honkai energy into pieces.

The other side was instinctively resisting the contamination of an alien force.

However much he poured in was however much was crushed.

Simply killing it would not have been difficult. Completely seizing control was far more troublesome. For a time, the two sides were locked in stalemate.

”Heh. Let’s see whether you’re stronger—or whether the Allspark, the Suniaster, and the Cocoon of Finality installed on my Eternal Snowfall are stronger.”

Boom!—

Setsuna mobilized even more corrosive power, colliding head-on with the chaos before him.

”Uh... so the Commander wants to control this thing, but it’s unwilling?”

Nyaruko’s ahoge curled slightly.

”You could put it that way. After all, Unicron is the incarnation of chaotic destruction. It’s not so easy to erode.”

Grey spread her hands.

”Too bad we can’t help right now. Uh... just keep an eye on it. Make sure that thing doesn’t come back to life.”

”Hmm...”

Nyaruko thought for a moment.

”Well... I might have a way?”

She leapt from the ship’s bridge and landed lightly beside Setsuna.

”Commander, I’ll assist you!!”

Eroding will and polluting concepts—this was practically a professional specialty for Cthulhu Outer Gods.

It was an innate racial trait.

”Hey!”

Nyaruko pressed one hand over Setsuna’s.

In an instant.

Another indescribable and ineffable force surged together with the authority of corrosion, pouring into Unicron.

Two chaotic energies collided. It was as though Unicron were facing some unfathomable ancient existence. Its shattered structure trembled, emitting a deep hum.

Then Setsuna immediately sensed it—the combined power of his and Nyaruko’s had broken through.

Like ink dripping into clear water, the corrosive energy spread at a visible speed.

From afar, black mist continuously seeped from Unicron’s wreckage, and it even began to slowly repair itself.

The shattered sections were reconstructed from the void. The massive holes torn through it gradually fused back together.

Of course, what fueled all of this was Setsuna’s Honkai energy.

”Ah?!”

The Transformers on Cybertron were completely baffled. They thought Unicron was about to resurrect again.

Panicked, they prepared for battle once more.

Yet as they watched, something felt off.

The suffocating pressure Unicron once exuded had vanished. In its place was another indescribable force.

As the erosion deepened, the overflowing power of the Outer God occasionally caused several tentacles to burst from Unicron’s hull, writhing wildly.

Each one stretched for hundreds of kilometers, twisted and grotesque. After thrashing about for a while, they were forced back inside by another restraining force.

”What the hell is that?!”

The Transformers on Cybertron were so shocked they nearly leaked engine oil.

Though they were mechanical lifeforms, they felt as though their sanity was slipping.

”Still.”

When the authority of the Herrscher of Corruption and the power of the Outer God completely seized every corner of it—

The gigantic metallic planet before them changed.

A faint layer of black coated its exterior. The shattered portions rapidly repaired themselves.

Setsuna withdrew his hand and closed his eyes, sensing for a moment.

The erosion had succeeded.

At this point, the chaos energy within Unicron had been fully assimilated by the Herrscher of Corruption and the Outer God.

It had transformed into something else—something under his control, devoid of self-awareness.

With a single thought from Setsuna—

Bzzzz—

The colossal object hovered before him, trembling slightly.

Its original chaotic will had been entirely erased by the power of the Outer God and the Herrscher of Corruption. Like other Honkai Beasts, it had become completely his puppet.

This was probably the largest thing he had ever eroded.

”Uh...”

The shipgirls and the engineering division watched from not far away.

”Commander, so this counts as...?”

Their original battle plan had been to completely eliminate Unicron and bring it back for dismantling and research. This was... a slight deviation.

”War trophy.”

Setsuna cleared his throat.

”Not only can we dismantle and study it, we can also use it as a tool in the future.”

”It’s a bit weak right now, but with some modifications, tossing it into other universes to beat people up sounds pretty good. Unicron is quite durable, after all.”

”?”

The accompanying scientists—Einstein, Edison, and the others—looked puzzled.

”You mean using it as a combat weapon? That actually does seem feasible...”

”I can also control it to devour planets.”

Setsuna considered further. Devouring planets to bring chaos and destruction had always been Unicron’s specialty.

”Then have the energy from those devoured planets transmitted back to me—to provide me with even more power.”

”???”

Everyone was stunned.

”So Unicron is basically me? No—did the Commander just refine Unicron?!”

Bang bang bang—

Grey planted one hand on her hip and knocked on the main console.

”Say it again. The Commander is the Starsea Emperor, thank you very much!”

...

Shhh—

With a wave of Setsuna’s hand, Unicron’s massive body steadily entered orbit around Alpha Centauri.

It became a gigantic metallic planet suspended in the starry void.

The authority of the Herrscher of Reason reconstructed the parts that had previously been destroyed, making it appear identical to the original Unicron.

Only now, faint black patterns lined the metallic shell covering the planet’s surface.

Its interior had already been completely occupied by the authority of the Herrscher of Corruption and the power of the Outer God. Every movement it made was determined solely by Setsuna’s will.

”Whoa—”

The nanorobot dismissed the gray goo fleet and, together with a group of young engineers from the engineering division as well as scientists like Einstein and Edison, impatiently boarded a transport ship and headed for Unicron’s body.

Rather than calling it a hull, it was more accurate to say that Unicron was a metallic sphere wrapped in chaotic energy.

It merely resembled a planetary warship. Gazing down from the enormous metal maw near its equator, all that could be seen within were violent storms of chaotic energy.

The engineering division pulled out all kinds of instruments to study Unicron’s structure. They had originally thought they would only be able to blow it apart and salvage a few components. Now, what stood before them was a complete Unicron.

Everyone was thrilled, practically wishing they could live here and study it thoroughly for years.

On Cybertron, with Unicron dealt with,

The Terrorcon forces that had been dropped from orbit lost all command and direction, and were soon completely wiped out by the Transformers.

”It’s over.”

Setsuna descended before the gathered Transformers and smiled.

”Unicron has been dealt with. From now on, you won’t have to worry about it emerging from the Dead Universe again to wreak havoc in the physical universe.”

”Ah?!...”

A considerable number of Autobots were still in a daze.

They looked up at the enormous metallic planet overhead, then at the vast fleet not far away.

”You... captured Unicron?”

Optimus Prime was stunned beyond words.

”Something like that.”

Setsuna considered for a moment.

”More precisely, I’ve taken control of it. From now on, Unicron will be used by us.”

”...”

Megatron and the other Decepticons exchanged glances, unsure what to say.

They had once revered Unicron because it symbolized destruction and chaos—perfectly aligned with the Decepticons’ relentless pursuit of power by any means necessary.

And yet the legendary, awe-inspiring Unicron had been reduced to scrap in a few blows by the Starsea Empire—and was now being turned into a tool.

Their idol’s aura shattered on the spot.

”I told you before—you should’ve worshipped the Commander instead.”

Gudako poked her head out from behind Setsuna.

”Look, when Scourge followed Unicron, what did Unicron give him? Just a high-powered fusion cannon and a bit more strength than you and Optimus Prime, right?”

”And he still got wrecked by me with a single smash from Barbatos.”

”If you worship the Commander—or rather, the Starsea Emperor—we can offer you far more than Unicron ever could.”

The Starsea Empire’s engineering and mechanical technology could only be described as unparalleled. The Transformers had already experienced that firsthand.

Leaving aside the bizarre weaponry, simply upgrading Optimus Prime at random would be enough for him to flatten the entire Decepticon faction.

”...”

Megatron pondered for a moment.

Looking up at the majestic fleet of the Starsea Empire, his mind trembled. Then he glanced at the newly subdued Unicron—once a god in his eyes, now nothing more than clay chickens and pottery dogs before the Empire.

Staring at the Eternal Snowfall, he felt as though he were gazing upon a force that transcended dimensions and surpassed comprehension.

Everything in this universe seemed insignificant before that Juggernaut.

Thud—thud—

Megatron stepped forward heavily, stopped before Setsuna, dropped to one knee, and extended a hand, his voice firm and low.

”I wish to pursue greater power.”

”Oh?”

Setsuna was not surprised.

”You want to follow me?”

”Yes.”

In Setsuna, he saw undeniable strength—power capable of suppressing all things. It was exactly what the Decepticons had always sought.

”Hey?!”

Bumblebee circled overhead.

”You’ve actually scared Megatron into this?!”

Before he could finish—

Smack—

Predaking slapped him so hard he nearly fell out of the sky.

”Who are you calling brother? You think you’re worthy of calling the Starsea Emperor your brother? Watch your mouth!”

”Wtf?!”

”What’s your problem?!”

Bumblebee nearly started a fight with him.

The Autobots led by Optimus Prime regarded Setsuna as a friend. The Decepticons, on the other hand, saw him as an idol.

Ultimate power. Absolute authority. Crushing all opposition without mercy. In some sense, the Starsea Empire’s style aligned perfectly with Decepticon ideology.

”...”

Setsuna pondered for a moment.

”I’ve already helped you rebuild Cybertron. From now on, live here in peace.”

”The Starsea Empire will provide you with some interstellar navigation technology. This universe still holds many places waiting to be explored. I’ll leave that to you.”

In the Transformers universe, beyond Cybertron and the solar system, there were far more distant regions awaiting development.

He felt that entrusting this mission to the Transformers was a good choice.

Shhh—

A brilliant star map projected before them.

”The Milky Way spans over more than one hundred thousand light-years in diameter—and it is only a small part of the Virgo Supercluster. There are millions of light-years and countless galaxies out there waiting for us to explore and conquer.”

”Go. In the name of the Starsea Empire—conquer this universe...”

Hiss—

With just a few words, a grand vision was painted in the minds of Megatron and the Decepticons.

”Ooooooh—”

The Decepticons were practically ready to board ships immediately and charge into the farthest corners of the cosmos, beating up aliens and waging glorious wars against bizarre civilizations.

”...”

Optimus Prime reflected that life was truly strange.

As expected of an imperial ruler—his ability to inspire was first-rate.

...

A few days later.

On Cybertron, the Transformers began constructing starships capable of long-distance interstellar travel.

Some of the technology came from Starsea Empire support. Some was developed locally.

The ships bore the emblem of the Starsea Empire, and their crews were entirely Transformers.

Megatron, along with the Decepticons, was already planning a grand expedition.

To conquer this galaxy and universe might take hundreds of thousands, millions, or even tens of millions of years. It didn’t matter. Transformers had no lifespan limit.

He had slept on Earth for millions of years. A little more time meant nothing.

Compared to endlessly bickering and fighting with Optimus Prime on Cybertron, conquering the universe sounded far more interesting.

”Then we’ll prepare to head back as well.”

Setsuna nodded to the two Transformer leaders.

”From now on, Optimus Prime will manage Cybertron, while Megatron expands outward. Hmm... that arrangement seems fitting.”

Both leaders were satisfied with the arrangement.

”Hey, come visit sometime~”

Bumblebee bumped fists with him again, then looked up at the fleet and Unicron overhead.

”But next time, don’t bring anything that scary. I’ll treat you to a meal? Or we can race.”

He thumped his chest.

”Just swapped in a new engine—zero to a hundred in 0.2 seconds. It’s a beast.”

Pfft—

Setsuna laughed and nodded.

He boarded the Eternal Snowfall and gave a final wave to the Transformers.

In the plaza below, the Autobots had erected a grand statue in his honor.

Carved into the base were his name and the emblem of the Starsea Empire, along with titles such as ”Friend of the Autobots,” ”Savior of Cybertron,” and ”Emperor of the Starsea Empire.”

”...Is building statues of great figures a universal tradition in every world?”

Setsuna couldn’t help but mutter.

”Starsea Emperor, Starsea Emperor... hmm...”

Formidable smacked her lips thoughtfully.

”It’s a little chuuni, but kind of domineering too. Not bad?”

”Give it a rest. Just call me Commander. I’m used to it.”

Setsuna rubbed Formidable’s head.

Boom—

The fleet passed through the transmission anchor point, flashing with blinding light before vanishing into the stars.

”Mission complete. Time to go home!”

—

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