Crossover Shipgirls: Building a Dimensional Empire from Scratch

”The Wisdom Cube… was absorbed?”

In the main building of the harbor, Enterprise and the flagship representatives of several fleets listened, wide-eyed, as Akashi recounted the incident.

Richelieu stood nearby, quietly nodding as she added details about what had happened.

”When Mr. Setsuna touched the Wisdom Cube, it dissolved like water and vanished into his hand. Then, he collapsed.”

”...”

The shipgirls exchanged uneasy glances.

Based on their long-term research on Wisdom Cubes, something like this should have been impossible.

Wisdom Cubes were designed for use with warships, imbuing them with sentience and creating shipgirls. They could also be used to manufacture Bulins.

But they were not supposed to interact with human bodies—humans and Cubes were entirely different entities.

”So… where is Mr. Setsuna now?”

Yat Sen asked.

”He’s still unconscious. Belfast and the Royal Maids are taking care of him.”

”His body appears unharmed, though he seems to have suffered a severe mental shock.”

Richelieu shook her head.

”Well, that’s a relief.”

The others sighed in unison.

”That was our last Wisdom Cube! Aaaaghhh!”

”Why did I even show it to him?!”

Akashi banged her head against the table repeatedly.

She wasn’t sure what hurt more—the irreplaceable Wisdom Cube being gone, or the 30 million Yen in lost revenue.

”Mr. Setsuna is a guest of the harbor. Why are you only concerned about the Cube? We’ll allocate more resources to make a new one.”

Richelieu frowned.

”I gave him a full physical checkup—he’s perfectly fine! Healthier than most people. No, healthier than shipgirls!”

Akashi wailed, continuing to bang her head.

”Healthier than shipgirls? Are you saying…”

Enterprise froze for a moment.

Shipgirls were anthropomorphized warships capable of wielding rigging weighing thousands of tons. Their power, reaction speed, and endurance were far beyond human capabilities, thanks to their Wisdom Cube-based energy systems.

”I’m saying he absorbed the Cube’s energy… without paying for it! I got scammed!”

”Ugh…”

Setsuna’s head throbbed, his consciousness hazy.

After the Wisdom Cube dissolved into his hand, he felt an immense force flood his mind, sweeping through him like a tidal wave.

Half-asleep, he caught fleeting glimpses of distorted images—Siren fleets, shipgirls, and strange, otherworldly devices.

It felt as though everything in the Azur Lane world was encapsulated within the Wisdom Cube, but the images flashed too quickly for him to make sense of them.

”Mr. Setsuna, Mr. Setsuna…?”

He heard someone calling his name.

”Hm?”

The whiteness moved closer, coming into focus as two soft, rounded shapes filling his vision in a way that startled him fully awake.

Belfast was standing by his bed, leaning over as she carefully tidied his blanket. Her long, silvery hair cascaded over her shoulders, strands falling forward to tickle Setsuna’s cheek. The low-cut neckline of her maid uniform hung dangerously close to his face, revealing the smooth, creamy curves of her chest and the alluring line of her cleavage barely contained by the fabric. At this angle, it was impossible to ignore, leaving him momentarily frozen.

”Belfast, you’re leaning on me,” he managed to mumble, his voice unsteady as he tried to avert his eyes.

”Oh! My apologies,” Belfast gasped softly, stepping back in a hurried yet graceful motion. A faint blush tinted her cheeks as she adjusted her uniform, her hands brushing lightly over the daring neckline as if to restore some semblance of propriety.

In the harbor, where every resident was a shipgirl, personal boundaries were a concept often ignored.

”You’re awake? Do you feel any discomfort?” Belfast asked, her tone soft yet attentive as she brushed her hair back into place. With a subtle breath, she regained her usual composed and professional demeanor.

”No, just a little dizzy.”

Setsuna sat up, checking himself over.

Thankfully, everything important was intact—he hadn’t turned into a shipgirl.

He wasn’t looking to experience life as a yuri protagonist.

”How long was I out?”

”Two days and sixteen hours.”

Belfast opened the curtains, letting the golden light of sunset spill into the room.

”Akashi and I ran several tests while you were unconscious. Don’t worry; no injuries or abnormalities were found.”

”However… the Wisdom Cube seems to have dissolved into your body. It’s strange—humans aren’t supposed to react to Wisdom Cubes.”

The maid tapped her chin thoughtfully.

”Do you feel any unusual changes?”

”I think I’ve gotten stronger?”

Setsuna stood up and flexed his hand.

He felt as if boundless energy coursed through him. All fatigue was gone, and his body seemed far healthier than the stressed, overworked husk he had back on Earth.

”Wisdom Cubes function as power sources. It’s normal for your strength to increase after absorbing one.”

Belfast explained.

”So… I swallowed a reactor?”

”That’s one way to put it. Additionally, Wisdom Cubes enhance the structural integrity of their hosts. Theoretically, you should now have resilience similar to ours.”

Belfast’s expression grew increasingly puzzled.

”?”

Setsuna paused.

Resilience comparable to the shipgirls of Azur Lane?

Did that mean he could tank torpedoes or shrug off naval cannon fire?

Hours Later—The Harbor’s Shore

Setsuna stood in the harbor’s test field, surrounded by the flagships of each fleet, Akashi, and a crowd of curious shipgirls.

”Hit me.”

Setsuna addressed the silver-haired, cat-like ears destroyer standing opposite him.

Under normal circumstances, he’d never dare to utter those words.

Destroyers might look like cute little girls, but their true forms were warships weighing thousands of tons. Even without their rigging, a full-force punch could probably send a whale or an elephant flying.

”How bold to challenge the great Yukikaze! You’ll regret this, hohoho~~”

The cat-like ears shipgirl pouted before dashing straight at him.

Boom!

Setsuna caught Yukikaze’s punch squarely, standing his ground.

He estimated the force behind it to be at least a hundred tons.

”Whoa!”

The watching battleship and carrier shipgirls widened their eyes in astonishment.

A human had withstood a destroyer’s strike. Unbelievable.

”Now I’m getting serious!”

Yukikaze jumped back two steps after seeing her attack fail. Her rigging materialized around her—a suite of armaments including three 127mm main guns and two anti-aircraft machine guns.

Her weapons roared to life, unleashing a hail of firepower on Setsuna.

Two torpedoes launched from her sides, initially the size of toys but transforming mid-air into 9-meter-long projectiles powerful enough to pierce a battleship’s side armor.

Boom!

When the smoke cleared, Setsuna stood unharmed, brushing dust off his clothes.

”Whoa!”

The shipgirls erupted in excitement.

”He really absorbed the Wisdom Cube!”

”Even 127mm cannons couldn’t hurt him! What about 380mm battleship cannons? No? Too much? What about 203mm?”

”Could he withstand Enterprise’s bombers?”

”Musashi! What are you doing?! Put those cannons away! You’ll actually kill someone with those!!!”

The crowd hurriedly restrained two overenthusiastic Sakura Empire battleships who had started preparing unauthorized weaponry.

An hour later.

The dust from the test field gradually settled. The Manjuus and Bulins scurried around with tools, repairing the site, which had been thoroughly riddled with craters and damage.

Even though the shipgirls couldn’t unleash their full power in land-based combat, their destructive potential was absurd, leaving the area looking as though it had been carpet-bombed.

”Based on our test results and evaluations, your physical strength is somewhere between a destroyer and a cruiser.”

Enterprise reviewed the experimental data in her hands as she spoke.

”Your durability, however, is closer to that of a heavy cruiser. As long as you don’t take a direct hit from a barrage of torpedoes, standard destroyer weaponry shouldn’t pose a threat to you.”

”Only at the level of a destroyer? That’s weaker than I expected.”

Setsuna stretched his limbs, testing his newfound capabilities.

During the tests, he had already sensed his limits.

He could handle attacks from destroyer-class shipgirls with ease, but when battleships or carriers got involved, he stood no chance.

Small-caliber guns posed no danger, but tanking heavy cruiser-grade cannons head-on was still a stretch.

”It might be because you and the Wisdom Cube haven’t fully synchronized yet. With practice, you should be able to harness more power.”

Enterprise offered her thoughts.

”Oh, that’s good to know.”

Even at destroyer strength, Setsuna felt he could wreak havoc on land.

He figured that, going forward, he’d at least be on par with a Yamato-class battleship or perhaps even an Iowa-class warship.

”But I don’t seem to have the ability to summon rigging or float on water?”

He suddenly realized that, unlike the shipgirls, he lacked weapons and maritime mobility.

His physical enhancements were evident, but his lack of a weapons system was glaring.

”That’s because your body isn’t a warship.”

Akashi’s expression was still heavy with resentment.

”The Wisdom Cube works by materializing human cognition into physical form.”

”To put it another way, if the user perceives warships as shipgirls, the Cube can grant sentience to those ships and transform them into humans.”

”But since your self-identity is human, naturally, you don’t have any rigging.”

”...”

Setsuna fell silent for a long moment.

”You’re telling me that because I think warships are people, the Cube can turn them into shipgirls? That’s some reality-bending, idealism-based sorcery!”

”And I can’t become a ’shipguy’ because I already think of myself as human?!”

”That’s correct.”

Akashi nodded earnestly.

”But if the Commander truly believes he’s something else, the Cube might transform you accordingly.”

Setsuna gained a newfound appreciation for the mind-boggling nature of Azur Lane’s black-box technology.

”So, if I genuinely believed I was a warship, I could project rigging? And if I believed I was a Gundam, I could summon the Unit-01, Strelizia, or Strike Freedom, or even Barbatos?”

”Mm-hmm.”

Akashi nodded again.

”Though I don’t know what a Gundam is, theoretically, that’s correct, meow.”

Despite the explanation, Setsuna found it impossible to rewrite his self-perception overnight.

After twenty-something years as a genuine human, no amount of self-hypnosis—chanting ”I’m a battleship” or ”I’m a Gundam”—made any difference.

It wasn’t as simple as adjusting one’s gender identity by declaring oneself a helicopter.

His subconscious wouldn’t cooperate, and neither would his body.

For now, he had to accept his limitations and find a solution later.

Still, gaining a physique comparable to a shipgirl was no small victory.

It also left him curious about what other abilities he might integrate in the future.

The only downside was Akashi constantly chasing him around for compensation, accusing him of freeloading a Wisdom Cube.

To placate her, Setsuna promised to help her sell refurbished crates to other multiverse worlds, exploiting alien customers together.

After some quick mental calculations, Akashi was overjoyed. She began camping out in her shop, diligently painting white crates gold in preparation for interdimensional market domination.

Five Days Later—Main Building, Harbor Headquarters

After several rounds of discussion—and resolving the drama surrounding Setsuna’s absorption of the harbor’s last Wisdom Cube—both parties finally reached a consensus on interdimensional cooperation.

Although Setsuna hadn’t been at the harbor long, his compatibility with the Wisdom Cube seemed to endear him to the shipgirls, earning him a noticeable increase in goodwill.

A few particularly enthusiastic ones had already started addressing him as ”Commander.”

”Ahem. On behalf of the entire Azur Lane fleet, I agree to establish a comprehensive partnership with your world.”

Enterprise, dressed in her white naval uniform, extended a document to Setsuna. The crisp, sleeveless blouse revealed her shoulders and upper arms, while the sharp black tie added a touch of formal authority.

Her short pleated skirt swayed slightly as she moved, the hemline daringly high, drawing attention to her slender legs, enhanced by the shimmer of her black stockings. The combination of her polished uniform and the flowing captain’s coat draped over her shoulders gave her an air of both professionalism and striking allure.

Setsuna found himself momentarily distracted by Enterprise’s presence as he reached out to take the document from her hand.

This agreement represented the culmination of numerous negotiations, countless meetings, and careful internal discussions among the shipgirls.

Setsuna opened the file. There were two copies, and the cover bore the Azur Lane logo, lending the agreement an air of formality.

It reminded him of the grand diplomatic summits between major nations back on Earth.

”On behalf of the harbor, I sign these trade, immigration, research, non-aggression, and military alliance agreements with you.”

”May our collaboration bring prosperity and development to both worlds.”