Crossover Shipgirls: Building a Dimensional Empire from Scratch

Early morning, on top of the naval base.

A Royal maid with long silver hair, dressed in her maid uniform, stood in front of the bedroom door. Holding a tray in one hand, she took a deep breath and knocked rhythmically three times.

Knock—knock—knock!

”Commander, it’s 7:20 a.m. I am here to assist you with washing up and breakfast.”

After receiving permission, Belfast opened the door and entered.

As the Royal Head Maid, she bore the responsibility of tending to the commander’s daily needs.

With practiced ease, she set the tray on the bedside table and walked to the floor-to-ceiling windows, pulling the curtains open.

Swish—

Sunlight flooded the room, bathing everyone inside in a golden glow.

Setsuna’s bedroom was located on the topmost floor of the main building. Standing by the circular floor-to-ceiling windows, one could overlook the distant Aegean Sea and Constantinople. The entirety of the city was spread out below, offering a panoramic view.

”Hmm…”

”Belfast… thank you for your hard work,” Setsuna murmured, shaking his head as he sat up in bed.

The head maid bent down to pick up his clothes from the floor. However, as she gathered them, she noticed certain peculiar items—like lace panties and stockings.

”Bring me a fresh one,” Taihou poked her head out of the blanket next to him. Her hair cascaded down her shoulders, and her crimson eyes were tinged with drowsiness and laziness.

”Why are you here every single day?” Belfast asked, rolling her eyes, entirely unsurprised.

”Of course, to prevent certain pests from harboring any untoward intentions~~” Taihou replied, her voice as seductive and charming as that of a newlywed bride.

She reached out with her delicate arm, picked up a glass of orange juice from the tray, took a small sip, and handed it to Setsuna.

”Commander, would you like Taihou to feed you?”

”...”

Belfast felt like she was about to go blind.

”Time’s tight. I’ll handle it myself,” Setsuna replied briskly, swiftly dressing and tidying his appearance.

He looked neither sleep-deprived nor sluggish—his physique was robust and healthy.

Initially, he hadn’t been sure he could keep up with Taihou. But after training extensively with the King of Knights, his physical abilities had improved significantly, enough to leave even an armored carrier begging for mercy. Adding one or two more into the mix wouldn’t be an issue.

”Are you going to practice magic again today…?”

”Commander, you’re truly amazing. Even after such exhausting daytime training, you can still…” Taihou remarked, tying her hair as she sat up.

”Of course,” Setsuna replied with a smug hum, laughing inwardly.

Mana Burst greatly enhanced physical capabilities, and naturally, specific areas could also be strengthened.

By the shore.

Akashi, Richelieu, Yat Sen, several Heroic Spirits, and a group of Bulins were already in place, equipment in hand.

Since Setsuna had pioneered a new method of utilizing the Wisdom Cube, the shipgirls decided to conduct a thorough investigation into the combination of Mana Burst and the Wisdom Cube.

”Commander, you’re playing with something we’ve never seen before, meow. Chaldea’s magic is so mysterious,” Akashi commented while attaching various monitoring devices to Setsuna.

”We haven’t seen this either! Who knew Mana Burst could be trained into this?!”

Jeanne Alter rubbed her head as she spoke.

After confirming that everything was in place, Setsuna focused his mind, extracting energy from the Wisdom Cube.

His entire body was surrounded by a faint blue glow.

He drew his sword, raised it high above his head, and mimicked the motion of the Sword of Promised Victory, slashing forcefully toward the distant sea.

Boom—

Blue energy erupted from the blade, creating massive waves.

A cruiser serving as the target on the distant sea surface was instantly pulverized, reduced to scattered components.

The accompanying shockwave triggered a minor earthquake, causing a tsunami to rise on the far shore.

The immense waves shimmered with silver light under the sun.

”That’s all we can say about what we just saw,” the onlookers remarked.

”This is way over the top! Is this how you’re supposed to use Mana Burst?” Jeanne Alter almost cursed aloud.

Gudako stood there muttering nonsense at the sea. She realized, as the protagonist of another world, that she had been completely outclassed by Setsuna. Not only was he better at piloting Gundams, but his mastery of magic was also leagues ahead.

”What about in your Gundam form?” Akashi asked, examining the data that had just come in.

”The Gundam form uses the beam saber as a medium to channel the mana, which requires more effort,” Setsuna explained.

He summoned Strike Freedom, raising its beam saber with both hands.

Watching a 20-meter-tall mech unleash an attack resembling the Sword of Promised Victory left the shipgirls and Heroic Spirits utterly baffled.

”What is this? Cyber magic?!”

Boom—

In Gundam form, the power was even greater than before. The resulting tsunami caused light rainfall over the sea surface for a while.

From afar, Bulins and small yellow chickens working the fields waved their hands frantically toward the group.

”Stop! Stop! If you keep going, the wheat will be flooded!”

”Hmm…”

”Interesting.”

After experimenting a few more times, Setsuna stopped, while Akashi stared thoughtfully at the results. She turned to the Heroic Spirits.

”As a comparison, could we ask you to demonstrate your Noble Phantasms?”

”I don’t mind.” Jeanne Alter and Artoria shrugged.

”Uh… it’s a bit inconvenient for me…” Jeanne d’Arc said awkwardly.

Her two Noble Phantasms consisted of one for defense and one for self-destruction—neither was well-suited for demonstrations.

”Then you two,” Setsuna said, gesturing for Artoria and Jeanne Alter to demonstrate their abilities.

”Ex… calibur!!!”

”Roar, My Fury!!!”

A burst of surprised exclamations came from the shipgirls watching from a distance, clueless about what was happening.

”Hmm…”

Akashi spent some time poring over several stacks of reports, her ears twitching.

”Commander, I think I’ve figured it out.”

”You’re using Mana Burst to directly project the energy from the Wisdom Cube.”

”Shipgirls use the Wisdom Cube to enhance their weapons, but your method is more straightforward.”

”Mm-hmm,” Setsuna nodded. That matched his own thoughts.

”What about the output?” he asked.

”In terms of raw power… your normal state Mana Burst is roughly equivalent to a small hydrogen bomb,” Akashi said. ”By Heroic Spirit standards, it’s comparable to an Anti-City Noble Phantasm, and slightly stronger than Jeanne Alter’s.”

”…”

Jeanne Alter pouted. Her Noble Phantasm was classified as Anti-Army, not Anti-City, making it weaker than Artoria’s.

”If you switch to a different medium, like using a Gundam’s beam saber for Mana Burst, the destructive power will be even greater…” Akashi added.

”I think you could probably defeat high-level Sirens like Purifier or Omitter in a one-on-one fight, meow.”

This evaluation was extremely high. After all, no shipgirl had ever claimed to be able to solo one of the higher-level, intelligent Sirens.

”???”

”Is the Cube really that powerful?!” Gudako exclaimed with excitement. If Mana Burst alone could rival Anti-City Noble Phantasms, she figured that mastering it would make her unstoppable in Chaldea and the Singularities.

She immediately grabbed Setsuna’s arm, adopting a cutesy tone.

”Boss—I mean, Commander? Do you have any more Wisdom Cubes?!”

”I do, but why not just study magic properly? This thing probably won’t work for you…” Setsuna replied, pulling out a pale blue Wisdom Cube.

Gudako held the Cube in her hand, rubbing it, but nothing happened.

She stared at it intently, concentrating all her focus, yet still no reaction.

Finally, she tried biting it, nearly breaking her teeth.

”Wisdom Cubes can only be used by shipgirls in principle, meow. The Commander is a special case,” Akashi explained, stopping Ritsuka Fujimaru from swallowing the Cube in her reckless attempt.

”Also, the Cube’s structure is extremely stable—probably wouldn’t even break under a hydrogen bomb, meow.”

”...”

”Fine, I’ll just go pilot a Gundam instead,” Gudako said, abandoning the thought. She wandered off, driving her Zaku to play elsewhere.

”However, Commander, you should keep in mind that the energy released through Mana Burst isn’t infinite. If you use it at high intensity for too long, your body will suffer damage,” Akashi cautioned.

Even if the Cube functioned like a reactor with endless energy output, the body’s capacity to handle it had limits.

”Got it,” Setsuna nodded, realizing he needed to continue strengthening his body.

He made a mental note to push his power from the level of an Anti-City Noble Phantasm to that of an Anti-Country Noble Phantasm—and eventually, to Anti-Star levels.

”Looking at it this way, you don’t really need to learn any additional techniques,” Artoria said, resting her chin on her hand.

”I was planning to teach you some swordsmanship, but now it feels unnecessary.”

The destructive power of Mana Burst already rivaled that of a Noble Phantasm.

Raw strength producing miracles—sheer force overcoming all obstacles.

Faced with an enemy, all Setsuna had to do was project the Wisdom Cube’s energy. If one strike wasn’t enough, he could simply fire again. Simple and efficient.

After all, most Noble Phantasms just converted mana into different forms.

For instance, Jeanne Alter used mana to create flames that burned enemies, while Artoria’s holy sword transformed mana into a light cannon.

There was no need to learn redundant techniques.

”Yeah, there’s no point in learning similar skills,” Setsuna agreed.

”However, in the future, it might be worth learning some special abilities—like defensive or rule-based Noble Phantasms. Something like Golden Rule or Lord Camelot… or even Chakravartin would be great. Hmm, I should think about which Singularity to visit next…”

”?”

The Heroic Spirits were confused but could sense that Setsuna was plotting something dangerous.

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