Crossover Shipgirls: Building a Dimensional Empire from Scratch

Crack, crack, crack...

On the outskirts of London stood a structure resembling Big Ben.

This was the headquarters of the Clock Tower. The minute hand atop the great building turned circle after circle, time slipping away bit by bit.

It was drawing ever closer to the deadline of the ultimatum.

Beneath the surface lay the true core region of the Clock Tower.

It was said that after the Age of Gods ended, a giant dragon nearly two kilometers long died underground. Its remains were scattered in fragments throughout the depths. In order to utilize the corpse as a source of magical energy, the Clock Tower had been built above it.

The first ten kilometers closest to the surface formed the mining city of Magisphia, which also served as the Clock Tower’s residential district. It had already been completely evacuated.

The once-prosperous underground academic metropolis now stood empty.

Another thirty kilometers down lay the Vein Corridor Od Vena—the Great Magic Circuit. This region was filled with enormous magical circuits.

Even though buried deep underground, each node displayed a different terrain.

There were lush jungles, snow-shrouded tundras, lands flowing with lava, acidic rivers dissolving the bedrock, and hills crackling with lightning...

Many Phantasmal Species from the Age of Gods also dwelled here—chimeras, serpents that materialized from shadows, colossal worms the size of trains with magic eyes, and more.

Only upon setting foot here could one truly feel that they had entered the kingdom of magic and the domain of magi.

Twenty kilometers below the Great Magic Circuit was a vast cavern.

All the magi of the Clock Tower who had resolved to defend the dignity of the Mage’s Association had gathered here.

Led by several Lords, together with the great mage families, they were arranging defensive magecraft throughout the surroundings.

This was the place where the dragon’s heart had been excavated. The dragon bones encasing it formed the most powerful mystic barrier on the surface world.

No matter how fierce the battle within this cavern, it would not affect the outside. In ordinary times, it served as a ritual ground and was not open to the public.

Now, it had become the Clock Tower’s final stronghold against the conquerors from another world, chosen for its exceptionally sturdy barrier—ideal for defensive warfare.

Nearly all the magi participating in the battle belonged to aristocratic families of the Clock Tower.

Bound together by lineage, they stood at the pinnacle of the Mage’s Association. According to the orders of the Starsea Empire, they were also the class whose interests would suffer the most.

To strip nobles of their status above others and reduce them to ordinary people under someone else’s rule—nine out of ten would never accept that.

Thus, the great aristocratic houses and prestigious lineages had tacitly gathered all their members, united in defense of their honor.

”Your body shall be entrusted to my banner, and my fate shall be bound to your blade.”

”...I am the one who shall accomplish all good in this world. I am the one who shall eradicate all evil in this world.”

”...Clad in the Three Great Command Seals of the Seven Days, come forth from the Wheel of Restraint and guard the scales!”

Whoosh—whoosh—

Brilliant light burst forth within the great cavern.

Using sacred relics, the magi began conducting successive Servant summons.

At a moment of life and death, the Mage’s Association’s former rules no longer mattered.

Any combat strength that could be of use was gathered without hesitation.

The Mage’s Association possessed quite a few treasured relics capable of targeting famous Heroic Spirits. Of course, considering this was not a Holy Grail War and lacking proper restraints, they only dared to summon Servants who were relatively stable according to records.

”Yo! Servant Lancer, answering the call.”

A certain blue lancer looked around in mild surprise, sensing that this summoning felt somewhat different from what he remembered.

”So it’s not a Holy Grail War, but you want me to deal with someone instead? Heh...”

”Defend this place. Once we withstand the first wave of attack, we will seek an opportunity to counterattack.”

The Lord of the Trambelio family wore a grave expression as he did his utmost to set magical traps throughout the area.

He did not know what methods the Starsea Empire would employ, nor how powerful the Angeloids and starships truly were.

But with the underground ruins of the Clock Tower at their backs, it gave them a measure of confidence.

”If only we could connect to the Root... tch...”

Some were unwilling to accept their predicament, regretting that the Clock Tower’s research into the Root had not advanced far enough for practical use.

Tick, tock—

When the second hand once again pointed to the topmost mark, the clock tower rang out with a resonant chime.

Dong, dong, dong—

At Chaldea and at the headquarters of the United Nations, a considerable number of magi and nations had accepted the proposal, surrendering and swearing loyalty.

After glancing at the list and receiving Setsuna’s approval, Sophon swiftly transmitted an order.

”The final deadline has passed. Begin the purge.”

”They’re here!!!”

The gathered magi looked upward tensely, bracing for battle.

They hoped the upper Great Magic Circuit would at least slow and exhaust the invaders.

Only one second passed.

Bzz—

BOOM!!!—

A blazing beam of light pierced down from the sky. A pale blue Tachyon Lance sliced straight through the earth.

The Clock Tower’s landmark structure was severed cleanly in half, the cut perfectly smooth. At the same time, a tunnel hundreds of meters in diameter and stretching dozens of kilometers was carved through the ground.

The upper underground mining city was instantly disintegrated into molecular particles by high-energy impact. Every node within the Great Magic Circuit was annihilated in an instant.

Erosion missiles and Angeloids dove down together. A significant portion of magi had no time to react, vaporized along with the traps they had painstakingly arranged.

No matter how vivid their imagination, they could never have envisioned that a starship’s air-to-ground strike would look like this.

The underground descended into utter chaos.

”Oh?”

”Leave some for me. I still want to see what magi from other worlds are like.”

A dragon girl with a long tail leapt down from the sky.

Accompanying her was a small squad of Heroic Spirits.

”Heh, a battle between Servants, is it?”

Just as Lancer and the other Heroic Spirits raised their fighting spirit, they looked up—and saw several familiar figures.

”Holy crap, the purple-haired hag!!!—”

”Gae Bolg Alternative! Pierce! Break through!—Gae Bolg of Piercing Death Flight!!”

Following close behind was a strange girl with long horns.

”Aaa... Aaa!!!—”

BOOM!!—

Within the vast cavern, Tiamat revealed her draconic form, nearly filling half the space.

With a casual strike, the earth shook violently, and even the entire underground trembled.

The elite magi of the Clock Tower and the Servants they had summoned were like children before the Second Beast—utterly incapable of resistance.

”?”

Some of the magi were stunned.

”We’re fighting Tiamat?! Are you serious?!”

”!!”

McDonell pressed one hand forward, aiming at that bizarre dragon girl as he began chanting an incantation.

Blazing flames coiled around his palm, intertwining with the wind before surging toward the enemy.

This was the burning magecraft he excelled at most—his peak offensive spell.

Smack—

Tohru casually swatted the flames apart.

”As expected, your so-called magecraft is just that—magecraft. It might be fine for a circus performance, but aren’t you embarrassed bringing it out for real combat?”

”Have you ever seen true magic? Dragon magic, you know.”

She floated high above the great cavern, gazing down arrogantly.

”Though you’ll only get to see it once in your lifetime.”

”—Receive it with gratitude.”

She clasped her hands together. A complex magic circle unfolded before her, the profound incantations within enough to drive any magus into madness.

”Magic of the Age of Gods! That’s magic from the Age of Gods!”

Some magi vaguely sensed in her spell the shadow of ancient deities and began shouting in panic.

”I surrender! I surrender! Please—”

”Too late. I’m not as kindhearted as the Commander.”

By nature, Tohru also belonged to the chaotic side. Aside from Setsuna and her companions in the capital, she regarded all other humans as insects.

Whoosh!—

Crimson dragonfire erupted, sweeping across the entire underground cavern beneath the Clock Tower.

A superheated blaze rivaling a star melted everything within.

Wails and shrieks echoed through the subterranean space.

Only after several hours did silence finally return to the great cavern, leaving behind absolute deathly stillness.

All resisting magi—and every node of the Great Magic Circuit—had been reduced to ashes beneath the dragonfire.

Empty.

A faint breeze drifted through, carrying away the remaining dust on the ground.

Nothing remained.

”Mission complete.”

Tohru reported to Setsuna through the holographic interface, wearing a sweet, charming smile as though it had been nothing more than a trivial task.

”...”

In Chaldea’s main hall, not a sound could be heard.

Some of the magi who had agreed to pledge loyalty—or who had come merely to observe in hopes of avoiding direct conflict—had witnessed the entire process.

Those mage aristocrats and prestigious families of the Clock Tower, whose legacies had stretched for over a thousand years, had been completely erased in a matter of minutes.

Any remnants would not escape the tracking pursuit of the Angeloids.

”And you?”

Gudako and Jeanne Alter swept their gazes across the remaining crowd.

Gulp—

After a moment of silence, someone swallowed.

”The Wandering Sea has accepted the proposal. We will abide by all arrangements and regulations of the Starsea Empire and the Magic Division.”

”The Atlas Institute has transferred all authority and will comply with the decree.”

Before overwhelming power—magic utterly incomprehensible and surpassing even the magecraft of the Age of Gods—all remaining magi fell silent, kneeling deeply and not daring to raise their heads.

Not even before their own teachers had they ever shown such reverence.

They had finally understood what kind of existence they were facing, and trembling, they submitted in loyalty.

”Oh? Earlier, who was it that looked down on us and casually decided to grant me a mere Fes rank like charity, even planning a background investigation and confinement in Chaldea?”

Gudako held grudges. Tilting her head, she suddenly spoke up.

”Ah—ah!!!”

The investigators who had come along nearly burst into tears, their voices shaking.

”I’m terribly... sorry. I—I didn’t know... I truly didn’t know...”

”Heh.”

Setsuna smiled faintly and waved a hand.

”Go on. Handle it yourselves. Give me a result that satisfies me.”

”!”

The crowd fell silent as cicadas in winter.

Such a demand was the hardest to fulfill. What counted as ’satisfactory’? It depended entirely on his mood. Mishandle it even slightly, and disaster would follow.

Yet they dared not voice the slightest objection and could only agree submissively.

”The remaining matters will be handled by the Magic Division. Prepare for return. Mm... Our rules are simple. Easy to understand, right?”