Crossover: The Problematic Deity of Arcadia

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"In One Month, Muzan Kibutsuji Dies"

Those were words only Ryo could say with absolute confidence in this world.

Ryo? As a five-digit in Little Garden, if he really wanted to, he could erase every trace of civilization from the face of the Earth—given enough time.

Well, that is, unless it was one of those ridiculously overpowered Earths like in Marvel, DC, or Dragon Ball.

That's why Ryo had never taken Muzan seriously.

He didn't come to the Demon Slayer world to fight Muzan. His real goal was to bring this world under Little Garden's jurisdiction in exchange for a promotion in status from the central authority.

That's what truly mattered to him.

But to do that… what he needed most was influence.

And what was "influence," really?

Ryo had started to figure that out back in the Bleach world.

To sum it up in two words: stir shit.

Let's take an example.

In the Bleach world, after Ryo—looking exactly like himself—defeated the captains of the Gotei 13, his influence score shot up to 9 points.

Why? Because he shook up the whole system. He left a mark so deep that most of the captains probably started having nightmares of getting one-shotted by him.

That kind of humiliation? Motivational fuel for them to train day and night, dreaming of revenge.

Their behavior changed. Their aura shifted. And that ripple effect spread like a virus to everyone around them.

Then, when everyone found out that he, Ryo Yagami, had teamed up with Aizen Sōsuke to overthrow the Soul King—even Old Man Yamamoto himself couldn't stay seated anymore.

Just look: Orihime heals Yamamoto's severed arm, and suddenly he forgives her for her "great betrayal" of siding with Ryo earlier.

Why? Simple—because of Ryo's influence.

Yamamoto needed both hands to stand a chance against him. That was the only reason he was willing to tolerate Orihime.

Hell, he even sent several captains to go after Kisuke Urahara—all because of Ryo.

That's the kind of impact Ryo had when he stirred things up in the Bleach world.

Now… what about Demon Slayer?

What could he possibly stir up here?

There's just the Demon Slayer Corps and demons. No Pillar Men, no Dark Council, no hidden third faction pulling strings in the shadows.

Just two sides: the demons and the demon slayers.

So if Ryo wanted influence here, he only had two options: side with the Demon Slayers or side with Muzan.

And siding with Muzan? Don't make him laugh.

Sure, Ryo could transform into a demon, manipulating the [Authority: Demon], but nothing like Muzan. The gap between them was wider than galaxies.

Would a human ever want to be buddies with a cockroach?

Absolutely not.

The sole interaction between humans and cockroaches is the satisfying crunch of a shoe sole.

So that leaves siding with the Demon Slayers.

And hey, Kagaya Ubuyashiki already served the whole organization up on a silver platter—wasn't that convenient?

Yeah. It was easy. Almost too easy.

But Ryo wasn't satisfied.

The Demon Slayers and demons were basically two underground factions quietly duking it out in the shadows of Taisho-era Japan. Sure, they had some societal impact.

But not enough. Not even close.

Ryo scoffed.

Just look at the Bleach world again.

Aizen controlled Hueco Mundo. Yamamoto ruled the Soul Society. Together, they both influenced how souls flowed through the human world.

And Ryo? He just tossed a pebble into that pond and watched his influence numbers skyrocket.

But in Demon Slayer? Even if he killed every last demon, it might take centuries before the human world even noticed.

It will be like: "Oh, wow, were there demons back in the Taisho period? That sounds kinda scary… Sooo let's make it a movie."

And that's it. End of the real story.

The influence score? Pathetically low. Ryo wasn't even sure he could hit 12 points with this setup.

So a new idea started forming in his head.

Kibutsuji Muzan is way too low-profile.

A king of demons whose name isn't even known to a thousand people? That's just embarrassing.

Ryo slowly closed his eyes.

When he opened them again, he turned to the expectant Kagaya and said calmly:

"From now on, all of the Ubuyashiki clan's assets will be under my control. In return, Kibutsuji Muzan will die this month."

"And the existence of both demons and the Demon Slayer Corps will be made public—across all of Japan."

Kagaya froze.

He didn't respond for a long moment.

When he finally came to, his voice was filled with concern:

"For the past thousand years, the Ubuyashiki clan has worked hand-in-hand with the authorities to suppress all knowledge of demons. If their existence is exposed now…"

Ryo interrupted coldly, "This isn't a request. It's a certainty."

He stared at Kagaya with calm, unwavering eyes.

"The demon king—driven to desperation by the fear of death—will lash out with everything he's got. That's inevitable."

"The darkest hour is just before dawn, Kagaya Ubuyashiki."

Kagaya blinked, then fell deep into thought.

After a long silence, he finally asked: "And after that? Will all the demons truly be gone?"

Ryo gave him a sideways glance, clearly surprised.

Then, he smiled. "Yes."

The joy on Kagaya's face was immediate. He bowed deeply. "Then the Ubuyashiki clan will fully cooperate with your plan."

Whether the government freaked out or not didn't matter to him anymore.

Ryo added with a faint smile, "I'll need cooperation from the Demon Slayer Corps as well."

Kagaya's expression shifted.

He hesitated.

"I'm afraid the members of the Corps might not listen to your orders…"

He knew the people in his organization better than anyone.

They were all problem children—traumatized, broken, surviving solely on vengeance. Most of them were orphans who'd watched their families get slaughtered by demons.

Mental instability was practically a job requirement.

Only someone like Kagaya—kind, fatherly, endlessly patient—could manage them.

But Ryo?

They'd clash instantly.

Ryo waved it off. "Doesn't matter. Just tell them leadership has changed. That's enough."

It's not like he actually wanted to be their boss. He was just here to rack up influence points.

Whether they accepted him as their leader or not—why would he care?

That time would be better spent figuring out how to power himself up.

He still hadn't reclaimed the Arcadia banner.

"I understand. I'll convene a Pillar Meeting shortly," Kagaya said with a sigh.

He could already feel the headache coming on.

It wasn't fear for himself.

He was just afraid one of the brats might mouth off and get themselves killed by Ryo before Muzan even got the chance.

Nope. He needed to do some serious emotional prep before the meeting.

Make sure nobody said anything dumb enough to get their head cut off.

With that, Kagaya took his leave, going off to get the Demon Slayer Corps ready for what was coming.

After he left, Ryo casually picked up his tea, took a sip, and muttered: "Way worse than your sister's."

"Huh? You think so too, Mr. Ryo?"

Kanae Kocho wasn't offended. She just laughed.

"I've always thought there was a big gap between me and Shinobu when it comes to this kind of thing. But if Kanao can learn from her, I won't have to worry anymore."

Ryo turned to glance at her—this smiling woman beside him—and let out a soft sigh.

"So you want to test whether demons and humans can really coexist?"

Kanae paused.

She hesitated, clearly conflicted. "…Can we?"

She just needed closure. She had to try, one way or another.

"Good. Come with me."

The two of them packed up, left a note, and walked out of the Butterfly Mansion together.

Just as they reached the gate, Ryo suddenly stopped.

He reached for his Zanpakuto—Byakuya—and said calmly: "Let me make something clear first."

"Hmm?" Kanae blinked at him, confused.

Then, Ryo's lips curled into a smirk.

And in the next instant, he released his Zanpakuto—and transformed.

Silvery-white hair cascaded down his back, horns curled from his temples, and wild, oppressive energy surged around him like a storm.

A horned demon god now stood before Kanae, golden eyes as cold as ice.

"From this moment forward, you will address me as Muzan... Lord Muzan Kibutsuji."

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