The battle at night

Sea Demons...

Creatures that should not exist in Pan-Human history.

Their forms resembled octopuses, yet they lacked a distinct head—replaced instead by gaping, worm-like maws lined with rows of jagged teeth. Their tentacles were massive but unusually short, covered in clusters of dark, unblinking eyes.

They were not creatures recorded in history but rather myths—tales whispered by sailors about horrors lurking in the deep.

Had these very creatures been the anomaly that twisted history into a Singularity?

That was likely what Fujimaru Ritsuka was thinking at this very moment.

But to me, someone who had played Fate/Grand Order, I knew that these monsters weren't the only reason this era had become a Singularity.

And their presence here?

It could only mean one thing—someone had deliberately summoned them, disrupting the course of human history.

The question was, who?

The game itself never revealed the true culprit behind the Sea Demons' presence in this era. But if I had to make a guess—based on everything I knew from my experience—one suspect stood out above all others.

Medea.

Not Medea, the Witch of Betrayal, but Medea before she became that infamous legend.

And she was not alone.

Half of the Argonauts were with her, led by their legendary captain.

At a glance, Medea looked innocent—her youthful face, gentle voice, and small frame made her seem like a harmless girl. But that was just a facade. Beneath that mask of fragility lurked something far more terrifying.

A cunning, dangerous intent.

An intent to destroy human history itself.

The first time I played Fate/Grand Order and reached this very Singularity, I had thought that the main enemy was Blackbeard—the infamous pirate, a Servant of the Rider class. His presence seemed to make sense. A notorious figure of the seas, a man driven by greed and desire. Who else would better fit the role of a villain in a battle on the open waters?

But then the game revealed the truth.

The true mastermind wasn't Blackbeard.

It was Jason.

Jason, the infamous captain of the Argonauts.

I still remember the shock I felt when the plot twisted in a direction I never expected. Jason, a figure celebrated in legend, was the villain of this story? It had caught me off guard. But looking back, that shock was nothing compared to what came next.

Because Jason himself… was just a puppet.

The real mastermind had been pulling the strings all along.

Medea.

It was all her doing.

The moment I reached the climax of the Singularity in the game, the truth unraveled. Medea had been manipulating Jason from the very start, using him like a disposable tool. He thought he was in control, but he was nothing more than a pawn.

And when she no longer had a use for him…

She discarded him.

I could still picture it clearly—the horrifying moment when she transformed Jason into one of the 72 Demon Pillars that served Solomon.

His screams.

The look of betrayal on his face.

Even now, the memory sent a chill down my spine.

That was the kind of person Medea was.

And if she was here, in this Singularity, then things were about to get far, far worse.

I clenched my fists.

The Sea Demons were only the beginning.

I sighed, then took a moment to scan my surroundings.

The battle had settled—at least for now.

My crew had successfully driven back the Sea Demons using barrels of explosive material.

The moment those barrels hit the water and erupted into towering flames, the grotesque creatures recoiled, their massive, tentacle-covered bodies writhing in pain as they retreated. The sheer force of the explosions had sent waves crashing against the side of the ship, leaving the deck slick with seawater and the lingering scent of gunpowder in the air.

I exhaled slowly. That should keep them at bay… for now.

From the corner of my eye, I caught sight of Fujimaru who standing not too far from me and Mash emerging onto the deck. She had arrived a little late—Mash had been occupied below, likely ensuring the ship's defenses were intact.

But even though she had only just joined the fight, her presence had made an immediate difference.

I watched as Fujimaru seamlessly coordinated with my crew, giving clear, precise orders that helped them push the Sea Demons back.

He wasn't a warrior. He didn't have the strength of a Heroic Spirit or the overwhelming presence of a king. And yet—he commanded people with an unwavering confidence, a calmness that felt completely at odds with the chaotic battlefield around him.

A true Commander.

I found myself admiring him more than before. It was no wonder he had survived against all odds, leading Chaldea through one impossible battle after another.

"…Not bad," I muttered under my breath.

My gaze returned to the Sea Demons.

I sighed again. If only I had chosen to imitate a Servant specialized in direct combat, I would have been able to fight properly. But unfortunately, my current form—Captain Nemo—wasn't meant for direct battles like this.

It was frustrating.

In the past, I had copied Servants who excelled in battle—knights, warriors, assassins. I had wielded their weapons, moved like them, fought like them. But Nemo fought using intelligence, strategy, and adaptability, not raw power. And honestly? That was way harder than I had expected.

And yet, despite my frustration, I had still boasted to Fujimaru earlier. I had said I would teach him how to fight on the ocean.

Hah. Look at me now.

Before I could dwell on that thought any longer, something shifted.

The Sea Demons, which had been writhing and shrieking in pain from the explosions, suddenly began pulling back—retreating into the dark abyss of the ocean.

Wait.

Why?

I narrowed my eyes. Creatures like these wouldn't just back off unless—

"Tch." My instincts kicked in, and I immediately barked out an order.

"Fire the cannons! Don't let them escape!"

The crew hesitated for only a moment before snapping into action, adjusting their aim toward the retreating Sea Demons.

I wasn't afraid of them. Not at all.

But I was tired of dealing with them.

If you let one escape, the next day, they'll come back with even more.

And I had a feeling that next time… the real nightmare would begin.

The thunderous roar of the cannons echoed across the ocean as my crew continued their relentless assault.

Each shot struck the retreating Sea Demons, sending up explosions of water, flame, and scattered remains. The sheer force of the bombardment shook the deck, making the ship tremble beneath my feet.

I watched them work with practiced efficiency, my gaze following their movements.

They were incredible.

Even though they weren't legendary warriors or Heroic Spirits, they fought as if they were. Every cannon fired in perfect sync, every reload smooth and precise. They moved with a confidence that made them seem like true veterans of naval warfare.

To think… these were the same people I had summoned using my Noble Phantasm.

When I first used The Act of Imitating to take on Captain Nemo's form, I had also summoned this crew when I was open my character profiles.

Then as when they're summoned I had to ask if they're know how to operate pirate ship and they're saying that's as long as it's was a ship they're can handle it.

I had believed them—but I quickly realized there were limits to what they knew.

Sure, they could sail the ship, navigate through storms, and keep the vessel in working order. But when it came to combat?

They were hopeless.

They lacked any real experience in

Defending themselves. They didn't know battle tactics, how to respond to an ambush, or even how to properly aim a cannon in real combat. If we had faced an actual naval battle, we would have been sunk in an instant.

I had to fix that.

And that's when I came up with an idea.

Explosive barrels.

If we weren't strong enough to fight head-on, then we just had to fight smart.

I shared my idea with the crew, half-expecting them to laugh at me. After all, I wasn't a real captain—I was just someone playing the part. I was imitating a legend, not living as one.

But to my surprise…

They didn't laugh.

They actually listened.

Not only that, but they respected my idea. They followed my instructions without hesitation, working together to craft and prepare the explosive barrels.

And then, when it was time for battle, they carried out the plan perfectly.

That wasn't all.

I also took it upon myself to teach them how to properly use the ship's cannons. At first, they were sloppy, fumbling with the controls and miscalculating their shots. But they learned—fast.

Faster than I expected.

In just a short time, they had gone from inexperienced sailors to a disciplined crew capable of fending off monstrous threats.

I folded my arms and watched as another cannonball found its mark, exploding against the flesh of a retreating Sea Demon. The creature let out a horrible screech before vanishing into the depths.

Yeah.

Maybe I really am starting to feel like a captain.

.

.

.

The battle was over.

The last of the Sea Demons had either sunk beneath the waves or been blasted apart by the crew's relentless cannon fire. The ocean, which had been a chaotic battlefield moments ago, was now eerily calm, save for the lingering scent of gunpowder in the salty air.

And then—

"Victory!"

A cheer erupted from my crew. Despite their exhaustion, they beamed with excitement, their youthful energy completely undiminished. The girl with short white hair, her cheeks smudged with soot, raised her fist in the air. "We did it, Captain!"

The others quickly followed suit, laughing and cheering as they celebrated our triumph. The girl with a ribbon on her head twirled in place, giggling. "That was amazing! Did you see how the barrels exploded? Boom! Just like the Captain planned!"

"Of course it worked!" another chimed in, adjusting her sleeves. "We made them with our own hands, after all!"

"And I fired the cannon just right!" added one of the smaller ones, puffing out her chest with pride. "Even the Sea Demons had to run away from us!"

I let out a small chuckle. Standing tall in the form of Captain Nemo, I watched as they swarmed around me, each one eager to share their personal moments of glory. It was amusing—these girls, so full of spirit, acting as if they had just conquered the seven seas.

"Well, I have to admit," I said, crossing my arms, "you all performed better than I expected."

The short-haired girl grinned wide. "So, does that mean we're the best crew you've ever had?"

I smirked. "The best, huh? You still have a long way to go before earning that title."

"Aww, Captain!" the ribbon-wearing girl whined playfully. "Can't you just say yes for once?"

I shook my head, amused. These girls… they might not be experienced warriors, but they had heart. And in the middle of a battle, sometimes that was more important than anything else.

As the laughter continued, a pair of familiar figures finally approached from side of the deck—Fujimaru Ritsuka and Mash Kyrielight.

Fujimaru wiped sweat from his forehead, looking both relieved and a little exhausted. "That was… something," he admitted, rubbing the back of his neck.

Mash, who stood beside him, nodded. "The Sea Demons were more coordinated than I expected. But thanks to the crew's efforts, we managed to drive them away."

I studied them both for a moment. I could tell they had worked hard during the fight—Mash's armor bore scratches, and Fujimaru's coat was slightly damp from the sea spray. But more than that, I could see it in their eyes. They weren't just survivors of this battle; they had actively helped turn the tide.

"Not bad," I said finally, giving them an approving nod. "You two did well out there."

Fujimaru blinked, then smiled. "Coming from our Captain? I'll take that as high praise."

Mash tilted her head slightly. "You sound impressed."

I smirked. "Let's just say… I underestimated you two a little."

I glanced toward my crew, who were still buzzing with excitement.

"It's not easy to work with an unfamiliar team, especially during a fight. But you handled it well. Coordinating with the crew, backing them up when needed—that takes skill."

Fujimaru let out a small chuckle. "Well, I had some help." He glanced at Mash, who nodded in agreement.

The ribbon-wearing girl suddenly hopped closer, her eyes shining with curiosity. "Hey, hey! Captain, do they get to be honorary crew members now?"

I raised an eyebrow. "Honorary crew members?"

"Yeah! Since they helped us win, shouldn't they get a title or something?"

The short-haired girl immediately latched onto the idea. "Ooooh, I like that! What should we call them? Assistant Captains?"

"Deckhands?" another suggested.

"Or maybe—"

Before the conversation spiraled completely out of control, I raised a hand. "Alright, alright, settle down," I said with a small smirk.

"I'll think about it."

A collective "Aww!" echoed from my crew, but their spirits remained high.

I turned back to Fujimaru and Mash, my expression growing slightly more serious.

"But really… good work out there. Both of you."

Fujimaru gave me a confident nod. "Same to you, Captain."

Mash smiled warmly. "Let's keep this up. We don't know what's coming next, but if we stick together, we'll get through it."

I glanced out toward the open sea. The battle was over, but the journey was far from finished.

For now, though, we had earned this moment of victory.

***

Author note:

If you're curious about Sea Demons, there are actually many types of them. However, in this chapter, I only mentioned one—the kind with tentacles. Though, to be honest, I'm not sure if "tentacles" is the right term, as I didn't pay much attention to the finer details, like their exact name.

If you have a better idea of how Sea Demons should look, feel free to share your thoughts in the comments!

Now, you might be wondering: Are Sea Demons actually part of this Singularity's lore? The answer is no, as far as I recall. But if I'm mistaken, feel free to correct me.

So why include them in this fanfic? Well, first, I wanted to add more excitement to the story. And second, while they may not exist in the lore, they do canonically exist in the gameplay.

By the way, I'm writing this based on my memories from when I played the game a long time ago.

To be honest, I still play it today, but I'm kind of bored because I'm stuck at the Temple of Solomon. Even though I cleared the Singularity long ago, my memory of it isn't as fresh as it used to be.

So that's why the chapter updates are so slow, it's because I'm still thinking about how to proceed with the story. Writing based on old memories is really difficult.