Crossover: The Problematic Deity of Arcadia

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The figure that appeared beside Rui was a woman.

She wore a black kimono and carried a biwa instrument. Her long, dark hair draped over her face, hiding most of her features—just like something out of a classic poem.

But Ryo, with his sharp, devilish eyes, saw straight through the veil—and what he saw was a massive, single eye staring back at him.

Creepy as hell.

Nakime looked around after she appeared, slowly turning her head as if scanning her surroundings.

Then she turned directly to Rui and asked in a monotone: "Lower Five. Where is Lord Muzan?"

Rui blinked, confused, then turned toward Ryo and blurted out: "Isn't Lord Muzan... right there?"

"…?"

Nakime stared at Rui, tilting her head slightly—clearly dumbfounded.

That's when Ryo smiled and gently said: "Alright, Rui. That's enough."

Rui let out a relieved sigh, assuming the moment was over. But Ryo's smile didn't fade.

"You're useless now."

Shk!

Blood sprayed like a burst of red mist. Droplets floated in the air.

A single slash, clean from Rui's right shoulder down to his left thigh—cutting him nearly in half.

Kanae stood frozen, staring blankly at the scene in shock. She hadn't expected this sudden, brutal turn.

Rui, mortally wounded and utterly confused, looked up at Ryo and whispered: "Why… Lord Muzan…"

Then it hit him.

'Oh… right. Because that's just what Muzan would do.'

And with that, he died.

His soul was purified by the Zanpakutō. No reincarnation, no afterlife. Gone.

Nakime, watching the scene unfold, was so terrified she dropped her biwa and fell to her knees.

"I—I sincerely apologize for not recognizing you immediately, Lord Muzan!" she cried, trembling.

Kanae blinked again, stunned.

Wait a second—this scene felt… familiar?

Wasn't there a beautiful white-haired demon kneeling and saying almost the same thing just now?

Was this… a thing?

Like, is it standard protocol for demons to see someone brutally murder another demon and immediately assume: "Yep, that's Muzan"?

Seriously, is this how they identify him? Just by sheer terror and murder vibes?

Kanae was starting to have doubts.

Could it be… was Ryo Yagami really Muzan Kibutsuji?

Maybe the real Muzan—now immune to sunlight and fully evolved—was just messing with her for fun?

How else could you explain demon after demon mistaking someone else for their original creator?

But… that couldn't be. Ryo promised Kagaya Ubuyashiki he'd kill Muzan. He can't exactly kill himself, right?

So either Ryo was really good at acting…

…or Muzan was seriously losing his grip.

While Kanae stood there in a daze, Ryo stepped forward and looked down at Nakime, who was now practically bowing to the floor in terror.

"You disappoint me, Nakime."

A personal attendant not recognizing Muzan? Did she buy that position off Craigslist or something?

"I-I truly am sorry!" Nakime stammered, trembling with fear.

No one knew Muzan's temperament better than her.

The king of demons, self-obsessed and cowardly, cared more about his image than the lives of his own kind.

His face—his pride—mattered more than anything. Insult that, and you'd die. No questions asked.

After all, Muzan's motto is basically: "I don't care what you think. I only care what I think."

Even if you didn't mean to offend him, if he felt offended—welp, you're dead.

Demons like her had no choice but to grovel and pray for mercy.

Nakime didn't want to die.

She hoped Muzan—if this really was Muzan—might spare her thanks to her unique blood demon art.

Then Ryo smiled, crouched down, and gently patted her head.

At the same time, he implanted a control-type demon spell, completely removing Muzan's influence.

Then he said softly, "Relax. Why would I ever kill you?"

With that same calm smile, he helped her to her feet and added:

"Come on. Let's head back to the Infinity Castle."

"Yes, Lord Muzan," Nakime replied, voice full of fear and respect.

Kanae's face contorted as she watched this absurd scene.

— — —

Meanwhile, in Edo.

Inside a quiet house, the real Muzan Kibutsuji—sporting his signature Michael Jackson look and white hat—sat reading a medical text.

A thousand years ago, he was turned into the first demon by a doctor's experimental treatment.

When he realized he'd become a hideous monster, he flew into a rage and killed the doctor.

Only afterward did he learn the medicine was incomplete.

It lacked one crucial ingredient: the elusive Blue Spider Lily.

That one mistake meant he couldn't walk in sunlight. He'd been trapped in the shadows ever since.

He didn't regret killing the doctor. He regretted not getting the recipe.

For a thousand years, that regret haunted him.

He'd scoured every medical text he could find—but never once did he see a mention of the Blue Spider Lily.

And without it, he couldn't become the perfect being he dreamed of.

Lately, Muzan was especially irritable.

"The Demon Slayer Corps killed a few more Lower Kizukis recently. They're probably churning out new Hashira again."

"And that bastard Yoriichi… if he hadn't invented the Breathing Techniques and passed them down, none of this would've happened."

Even after five hundred years, Muzan still seethed at the memory of Yoriichi Tsugikuni—the strongest man ever.

The man was long dead, but somehow still screwing Muzan over from beyond the grave.

Thanks to those damn breathing styles, demon slayers were taking out Lower Kizuki left and right like it was a sport.

Nowadays, the requirement to become a Hashira was to kill a Lower Kizuki. The disrespect was unreal.

Muzan was starting to wonder if the Lower Kizuki were even worth keeping around.

They couldn't protect him. If anything, he had to protect them.

What was the point?

And just then, Muzan felt something that made his stomach drop.

Nakime, whom he kept under constant surveillance, had left the Infinity Castle.

"Wait, what? She left the castle? Without my command? How dare she?!"

He jumped up in panic, pacing back and forth like a nervous wreck.

A thousand-year-old demon lord, biting his nails and sweating bullets.

"She… betrayed me? No way. She wouldn't dare…"

In a panic, Muzan tried to activate the blood spell he'd placed on Nakime.

Nothing.

No response.

"She really betrayed me!!"

Now he was really freaking out.

And right then, another signal blinked out.

Lower Five Kizuki—Rui. Connection lost.

"Rui's dead? Was it Nakime?!"

Muzan's fear turned to outright dread.

He immediately activated a secret ability buried deep in all demons: the power to view their final moments before death.

For weaker demons, the image was fuzzy. But for Lower Kizuki and above? Crystal clear.

And what he saw next made his blood run cold.

A man appeared.

Silver hair, sharp horns, a face like ice. Effortlessly, he sliced Rui apart like it was nothing.

Even Rui died in stunned disbelief.

Muzan stared at the image.

At that moment, Muzan understood.

.

.

.