The One Punch Man (a.k.a Saitama) in Demon Slayer

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A World Without Light

The entire village was swallowed by an unnatural darkness.

Even the raging fires that had consumed Shiranomura flickered and died, as if the very flames had been suffocated. The air became thick and oppressive, pressing down on the Hashira like an invisible force.

For the first time in his life, Rengoku couldn't see the sun.

"This isn't just darkness," Shinobu murmured, gripping her sword. "It's almost like it's… alive."

Giyu narrowed his eyes. "If demons can move freely even during the day… then the balance we've maintained for centuries will be shattered."

Tenma chuckled softly, his eerie silver eyes glowing in the void. "Ah… I see the horror in your eyes. Good. You understand, don't you? This world no longer belongs to humans. The sun will never rise again."

Tengen Uzui cracked his knuckles, unfazed. "Tch. What an unflashy way to start a fight." He twirled his dual Nichirin blades, getting into a stance. "So, what? You're just gonna make things dark and expect us to roll over?"

Muichiro, who had been silent, suddenly spoke. "He's not just making things dark. He's bending reality itself."

Tenma grinned. "Clever child. Unlike you primitive humans, we demons do not simply wield swords and swing them blindly. We reshape existence."

The ground beneath their feet began to ripple as if turning into a liquid void.

Rengoku immediately reacted, gripping the hilt of his sword. "We must strike him down before this power spreads further!"

Shinobu nodded. "Agreed. If this darkness expands beyond this village, the entire world will—"

But before she could finish, something moved in the shadows.

A beast-like creature emerged from the darkness—its body warped and disfigured, eyes glowing with an unnatural red hue. Then another appeared. And another.

Hundreds.

They were not demons.

They were not beasts.

They were something entirely new.

Even Tenma seemed surprised. "Oh? So it seems Mizan's creations can thrive in my world of darkness…"

Shinobu's heart pounded. "What… are those things?"

Tengen clicked his tongue. "Well, whatever they are, they're ugly as hell."

The creatures snarled, their forms constantly shifting, as if they were made of the shadows themselves.

Then—they attacked.

Saitama vs. the Swarm

As the creatures lunged, Saitama simply sighed.

"Man, you guys just don't quit, huh?"

A claw slashed toward his face.

BAM!

Before it could even touch him, Saitama flicked the creature with his finger—and it instantly exploded into a mist of darkness.

Another beast leaped at him—only for Saitama to swat it like a fly.

BOOM!

The ground shook from the impact, sending a shockwave through the battlefield.

The Hashira, already used to insane fights, still couldn't believe what they were witnessing.

Tengen's mouth twitched. "Okay, I'm just gonna say it—this guy's ridiculous."

Muichiro, still emotionless, muttered, "How is he doing that…?"

Saitama, meanwhile, continued swatting away the monsters like they were annoying mosquitoes.

Tenma, however, wasn't impressed.

"I see. You rely on overwhelming force," he mused. "How… dull."

Raising his hand, he clenched his fingers into a fist.

The darkness around him condensed—and in an instant, the entire battlefield shifted.

Reality Warps – The Black Labyrinth

The world collapsed and reformed—what was once a burning village twisted into an endless maze of black pillars and walls, stretching infinitely.

Shinobu gasped. "What… what is this?"

Tenma's voice echoed from all directions. "A space where I alone control the rules." His laughter drifted through the void. "Let's see if your hero can survive in a world where brute force means nothing."

Saitama scratched his head. "Ugh. More complicated stuff. This is getting annoying."

Rengoku clenched his sword. "Regardless of his tricks, our mission remains the same. We must cut him down!"

And with that—the real battle began.

To Be Continued…

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Chapter Notes:

Tenma reveals the true nature of his ability—he can not only create darkness but alter reality itself.

New creatures born from the darkness appear, neither demon nor beast.

Saitama easily destroys them, shocking the Hashira again.

Tenma traps everyone in a new battlefield—The Black Labyrinth, where brute force may not be enough.

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