[FATE] OP Demon King Across Multiverse!

The sight before them was unexpected.

As the dust settled from their clash, Ryuu and Artoria could see the devastating aftermath of their combined techniques.

The wind-enhanced flames had fused into a chaotic spiral of destruction—something neither of them had anticipated.

For a brief moment, Ryuu felt a surge of excitement.

"So, my abilities can be combined with a Servant's…"

But before he could analyze further, his body gave out.

The dragon transformation dissipated, and he collapsed onto one knee, gasping for breath.

The battle had pushed him to his limits.

This was undeniable proof—the gap between him and a Servant was still massive.

Even without Excalibur's full power, Artoria had still dominated the fight.

But…

Ryuu clenched his fist.

Even though he lost, the fight had proven something important.

If a Servant doesn't unleash their Noble Phantasm, he can hold his own.

"That means… as long as I play my cards right, I can fight other Masters without issue."

His confidence grew.

The first step was gathering more intelligence.

---

"Master, are you alright?"

Artoria's voice pulled him back to reality.

"Yeah, just overdid it. Nothing a bit of rest won't fix."

With her support, Ryuu returned to their temporary base, collapsing onto his bed.

As he lay there, he began to strategize.

Of his three available summoning slots, Artoria was already locked in.

That left two more openings.

Ryuu needed to be selective.

He couldn't waste a contract on weaklings.

The next Servants he summoned had to be strong, skilled, and versatile.

For now, though…

The priority was gathering intel.

---

Ryuu slept for an entire day.

When he finally woke up, it was already morning.

Artoria, who had been standing guard the entire time, immediately approached him.

"Master, you're awake. How do you feel?"

"I'm fine. No need to worry."

As he stretched, he suddenly realized something—

His stomach growled.

"Shit. I really slept for a whole day, huh?"

Before anything else, he needed to eat.

"Saber, I'm heading out to buy some food. You should rest—this place is built on a leyline, so it'll help restore your mana faster."

"No, Master. I will accompany you."

"Nah, it's fine. After that last battle, I doubt anyone will try something so soon."

Without giving Artoria a chance to argue, Ryuu walked out the door.

---

His money situation was dire.

The last time he took Artoria out to eat, he spent every last bit he had.

Which meant—

It was time to "borrow" some funds.

His pickpocketing skills were top-tier.

But…

Just as he was about to make his move, someone grabbed his wrist.

A voice spoke from beside him—

"Yo, kid. With a face that good-looking, resorting to pickpocketing makes me feel ashamed for you."

Ryuu froze.

He had been caught.

For the first time in a long time, he felt the deep malice of the world.

Slowly turning his head, he saw a man wearing a blue robe, lined with black.

A smirk played on the man's lips, his crimson eyes full of amusement.

Ryuu's expression twitched.

"Oh, for fuck's sake… Cu Chulainn?"

---

Normally, this wouldn't be an issue.

But there was a problem.

This wasn't the usual Cu Chulainn.

The man before him wasn't a Lancer.

Instead, he wore the robes of a Caster.

Ryuu's mind raced.

"Why the hell is Cu Chulainn a Caster in this war?"

Before he could process further, Cu Chulainn clicked his tongue.

"Oi, I asked you a question. Don't ignore me, kid."

Ryuu quickly hid his Command Seals, but Cu Chulainn's sharp eyes caught the movement.

His smirk widened.

"Hah. You're a Master, huh? Pretty bold, walking around alone."

Just then—

A female voice called out.

"Caster, hurry up! I need help carrying these!"

A woman approached, likely Cu Chulainn's Master.

With an annoyed sigh, Cu Chulainn let go of Ryuu.

"Lucky you, kid. Guess I'll let you go this time."

As he walked away, Ryuu called out—

"Oi, Cu Chulainn."

The Irish warrior paused.

Ryuu's expression turned serious.

"After the world burns, meet me at Fuyuki Bridge."

For a split second, Cu Chulainn's eyes sharpened.

But before he could respond, Ryuu had already disappeared into the crowd.

---

Ryuu's chest tightened.

Memories flooded his mind.

The burning city. The polluted sky. The name "Leif."

His heart pounded.

"Shit. This isn't just an altered Grail War. It's the prologue to Singularity F."

If that was true—

Then Leif would be appearing soon.

Which meant…

He had to get back to Artoria. Now.

---

But before Ryuu could make it back, another event was already unfolding.

A dark shadow emerged in front of Artoria, materializing out of thin air.

She gripped Excalibur tightly, sensing the immense magical power radiating from him.

"Who are you?"

The man before her smiled.

"I am Solomon."

Artoria's grip tightened.

"Are you part of the Holy Grail War?"

"Hah! The Holy Grail War? No, no… the real war is only just beginning."

The mysterious figure extended his hand.

A golden, rhombus-shaped artifact appeared in his palm.

"This is the Holy Grail. The true wish-granting device. And now… it's yours, Saber."

---

Artoria instinctively recoiled.

"What nonsense is this? I would never accept such a thing!"

Solomon's smile didn't waver.

He simply raised the artifact, and golden light enveloped Artoria's body.

Her eyes widened in shock as raw magical energy poured into her.

Her body shook violently, dark veins spreading across her skin.

"What… is this…?!"

A black aura surged from the artifact, engulfing her in an abyssal void.

Her light blue armor darkened, warping into deep black steel.

Her golden hair dimmed, and her emerald eyes turned hollow.

The King of Knights was no more.

---

Solomon watched in satisfaction as Artoria succumbed to the darkness.

"A disobedient Servant is of no use."

With a flick of his wrist, the corrupting force solidified.

And just like that—

Artoria Alter was born.

As he vanished into the void, his voice echoed—

"The Grand Order… begins now."

And so—

The true Holy Grail War began.

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