Crossover: The Problematic Deity of Arcadia

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"When you say 'Hashira'… you mean her?"

The Kizuki demon froze, his eyes flicking toward Kanae Kocho in her Demon Slayer uniform. His voice stuttered in disbelief.

"Sh-she's a Hashira?"

A member of the Demon Slayer Corps standing next to Muzan was already weird enough. 

But a Hashira?

Now that was insane.

Hadn't Muzan himself always said Hashiras must be killed on sight? And now he's… holding one in his arms?

"Yep, that's me."

Still snuggled in Muzan's embrace, Kanae smiled sweetly, cheeks tinged pink with shyness.

"I'm Kanae Kocho, the Flower Hashira of the Demon Slayer Corps. Nice to meet you, gentlemen."

"If possible, I hope we can all get along."

That bright, cheerful smile of hers left a few demons completely stunned.

Big sis… are you seriously okay?

You're a Hashira. A HASHIRA! And do you know where you are right now?

The demon capital—Infinity Castle.

And not just that, the entire Twelve Kizuki are present.

And you—you're being held by Muzan Kibutsuji himself! What the hell are you smiling for?!

One of the demons, unable to process the bizarre scene, glanced at Kanae, then at Ryo, and finally clenched his teeth.

"If Lord Muzan commands it, I'll kill her."

BOOM!

A sudden surge of pressure exploded across the room.

With the stench of scorched flesh hanging in the air, the demon who had spoken evaporated on the spot—completely vaporized by the sheer force of the attack.

The remaining ten demons slowly turned their heads toward the smoldering ground, then back at Ryo, who was just lowering his finger.

Only then did they realize their backs were already drenched in sweat.

Ryo grinned, lifting Kanae's chin playfully.

"Looks like I've already taken care of the guy who wanted to kill you~"

"Thank you~" Kanae replied with a gentle smile, though whatever she was really thinking remained locked inside her own mind.

The four surviving Lower Kizuki could barely hold in their curses.

That guy had practically thrown himself at Muzan's feet, handing over full authority—he basically called himself Muzan's loyal dog, ready to bite whoever he was told to.

And what did that get him?

Instant death. Wiped from existence.

Where's the justice in that?! Where's the damn logic?!

Still, in a weird way… that was classic Muzan.

As Ryo continued to tease Kanae, he turned back to the others, his tone still light but firm.

"The Demon Slayer Corps is no longer a threat. Understood?"

The demons exchanged glances, sneaking side-eyes at Kanae while mentally cursing her as a walking disaster.

But outwardly, they all answered in unison: "Understood!"

Ryo narrowed his eyes and smiled again.

"Good. Now, back to what we were discussing."

"I've come to the conclusion that the Lower Kizuki are… unnecessary."

"So—who's for it, and who's against?"

Kokushibo, Upper Kizuki One, closed his main eyes while his remaining four scanned the room.

"The six Upper Kizuki fully support Lord Muzan's decision."

The words hadn't even finished echoing before the remaining Lower Kizuki collectively panicked.

One of them, in a barely audible whisper, muttered: "Shit."

Then, without another word, he turned and bolted—running on all fours, cursing the fact that he wasn't born with more legs.

But Ryo simply raised his left hand, fingers slowly spreading… then clenched his fist.

POP!

The fleeing demon exploded midair—like a grotesque firework.

Two more tried to run, but the moment they moved, they too burst apart without warning.

Only one Lower Kizuki remained, standing there frozen, eyes blank as he stared at Ryo like he still hadn't processed anything.

Kanae blinked at the sight and asked gently, "Aren't you going to run?"

The demon glanced at her, then turned away and crouched, tracing a bloodstained patch of floor with a dreamy look on his face.

"It's… beautiful~"

Ryo raised an eyebrow, genuinely curious.

"You think dying like that is beautiful?"

"Yes, Lord Muzan. If it's possible… I'd like to die from such a beautiful technique too."

The remaining Upper Kizuki mentally facepalmed.

This guy… might've just saved his own skin.

Because if there's one thing Muzan hates, it's being told what to do. And this demon just requested a specific way to die?

Knowing Muzan, he'd probably do the opposite just to spite him. Like… giving him more power instead.

That's why some of the Upper Kizuki figured this weirdo might actually survive.

But Ryo just smiled.

"Sure, I'll grant your wish."

POP!

There went the last Lower Kizuki. Another demon turned into fireworks.

Kanae looked a bit conflicted, but deep down she agreed—Ryo hadn't done anything wrong.

After all, that guy wanted to die. That's basically suicide, right?

She sighed and turned toward the Upper Kizuki—only to see all six of them looking extremely uncomfortable.

"Eh? What's with those faces?"

They all looked at her awkwardly, but it was Kokushibo who finally replied, stiffly: "It's… nothing."

"Really?" Kanae exhaled softly and leaned more snugly into Ryo's embrace.

Ryo gave her a reassuring pat on the back before smiling at the group.

"The extras have been dealt with. Now, let's get to the real agenda."

The Upper Kizuki didn't bat an eye. Human concepts like sympathy meant nothing to demons.

In fact, now that they knew they weren't next in line to die, Upper Kizuki Six—Daki—even lifted her chin and sneered at the scattered blood on the floor like it was trash.

Then Upper Kizuki Four, the old man Gyokko, laughed and said:

"Whatever Lord Muzan commands, we'll follow it to the end. We exist to fulfill your greatest desire."

Ryo arched a brow, amused. "Greatest desire, huh?"

"Yes!" Gyokko grinned like a fool. "We'll find the Blue Spider Lily and help you become the perfect, ultimate being!"

The moment those words left his mouth, panic set in.

Daki and Hantengu both flinched internally.

Because that line? That was dangerous.

Knowing Muzan, he'd probably demand they find the Blue Spider Lily within three days—and if they failed, well… they'd go out just like the Lower Kizuki.

All the Upper Kizuki, except Kokushibo, immediately felt the pressure settle in. Kokushibo, being more of a partner than a subordinate, stayed calm.

Ryo looked around at the six Upper Kizuki, smiling again.

"The Blue Spider Lily, huh? That little flower that only blooms during the day? Yeah, we don't need that anymore."

The Upper Kizuki were visibly stunned.

Gyokko, ever the suck-up, immediately dropped to his knees.

"Congratulations, Lord Muzan, for conquering the sun! Immortal and eternal, now truly the perfect being!"

The rest of the Upper Kizuki were still reeling from Ryo's declaration, but they couldn't help thinking Gyokko was a shameless bootlicker.

Still… something clicked in their minds.

If Muzan knew the Blue Spider Lily only bloomed during the day, that meant…

He must've already found it. Which meant he had finally overcome the sun.

It also explained why he'd never found the flower for a thousand years—it bloomed in daylight, when demons couldn't go outside.

But if a human got it for him…

Kokushibo shifted his gaze toward Kanae. Everything started to make sense.

If someone offered Muzan the Blue Spider Lily—then even a Demon Slayer, even someone with half a brain—Muzan would probably cherish them like a treasure.

Everything fit perfectly now.

Muzan Kibutsuji… had become the ultimate being.

Meanwhile, Ryo ignored the reactions, his voice calm and deliberate:

"Since I've conquered the sun, there's no need to call myself Muzan Kibutsuji anymore."

"From now on, my name will be Ryo Yagami."

"Yes!" x6

The six Upper Kizuki shouted in perfect unison.

Ryo burst into laughter.

"Excellent. The time is right."

"The Heian Era shall rise again. A world where humans rule the day—and demons rule the night—is coming back!"

"Everyone, prepare yourselves!"

"In seven days, gather every demon in Edo. We're going to build an empire of the night!"

"YES—!!" ×6

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