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

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The night sky was still thick with smoke as flames consumed what remained of Shiranomura. The villagers who managed to escape huddled in terror at the outskirts, their faces pale with shock. The massive Beast Gate still pulsed in the center of the village, its eerie glow casting long shadows across the ruins.

But the battle had already ended—Saitama had ended it in one punch.

The surviving beasts, once proud and confident, now trembled as they looked at the bald man standing in front of them. Their leader, Lord Shinkuro, had been obliterated before he could even attack.

A smaller beast, resembling a wolf with glowing blue eyes, growled under its breath. "This... this is impossible! How could Lord Shinkuro be defeated in an instant?"

Another beast, a panther-like creature with a humanoid form, clenched its fists. "That man… he's a monster!"

Saitama, standing among the destruction, simply sighed. "Man, I was hoping for something a little more exciting…" He glanced around at the remaining beasts. "You guys wanna keep going or what?"

The beasts exchanged nervous glances. Then—they ran.

Their once fearsome roars turned into panicked howls as they retreated through the Beast Gate, vanishing into the swirling darkness. The portal pulsed violently for a moment before sealing shut, leaving only a deep scar on the ground where it had once stood.

Saitama rubbed his chin. "Huh. So they can just run back into their little hole? That's kinda lame."

Just as he was about to turn away, a powerful gust of wind swept through the area.

The Demon Slayer Corps had arrived.

The Hashira's Reaction

Descending from the sky with blinding speed, Tengen Uzui landed first, his dual blades gleaming in the firelight. "Huh? The village is already destroyed?" His sharp eyes scanned the area before locking onto Saitama. "And who the hell are you?"

Behind him, Rengoku, Giyu, Shinobu, and Muichiro arrived, their expressions tense as they took in the scene.

"Where are the creatures?" Rengoku demanded. "We came prepared for battle, yet I see no enemies."

Shinobu tilted her head, eyes narrowing. "Strange… I sense no demon energy. But the destruction here is very real."

Giyu's gaze lingered on the remnants of the Beast Gate. "This wasn't Muzan's doing…"

Muichiro's usual blank expression flickered with something close to curiosity as he focused on Saitama. "Did you… fight them?"

Saitama, unbothered by the sudden attention, simply replied, "Oh yeah, I punched one, and the others ran away."

Silence.

Tengen blinked. "…You punched one?"

"Yeah, they exploded or something," Saitama said casually. "Didn't even get to see what they could do."

Rengoku frowned. "Impossible. Even high-ranked demons do not die from a single strike unless struck by Nichirin blades or sunlight."

Shinobu stepped closer, studying Saitama with a calculating gaze. "You don't look like a Demon Slayer. No uniform, no sword… yet you say you took down these monsters alone?"

Saitama shrugged. "I mean, yeah? They weren't that strong."

The Hashira exchanged glances.

This bald man, dressed in a plain hero suit, had single-handedly wiped out an enemy force that had left an entire village in ruins?

Muichiro stared at him blankly. "Are you lying?"

Saitama blinked. "Why would I lie?"

Tengen crossed his arms, unimpressed. "I don't know, maybe you just like talking big."

At that moment, the wind shifted—and a new, chilling presence filled the air.

A New Threat Approaches

From the shadows of the burning wreckage, a slow, rhythmic clapping echoed through the silence.

"Splendid," a deep, melodic voice spoke.

From behind a collapsed house, a figure stepped forward.

A demon, but unlike any they had seen before.

He was tall and draped in flowing black robes with silver markings resembling celestial patterns. His skin was a dark, eerie shade of blue, and his eyes glowed like twin moons in the night. He carried himself with an unnatural elegance, his long silver hair cascading over his shoulders.

Shinobu's eyes sharpened. "Who… is this?"

The figure smiled. "Ah… forgive my late arrival. I had hoped to witness the power of the Beast Gates firsthand, but it seems I was… too slow." His eyes locked onto Saitama, a flicker of interest flashing across his face.

"You," he said. "You're not from this world, are you?"

The Hashira stiffened.

Saitama blinked. "Huh?"

The demon let out a low chuckle. "Fascinating." He raised his hand, and in an instant—the air around them darkened.

A suffocating wave of shadows engulfed the village, blotting out the sky itself.

Rengoku's grip tightened around his sword. "This darkness… it's unnatural!"

Shinobu's breath hitched. "It feels heavy… like it's pressing down on us."

The demon smirked. "Allow me to introduce myself. I am Tenma, the Demon of Eternal Night. By Lord Muzan's will, I bring forth an endless darkness, allowing our kind to roam freely… even under the sun."

The realization struck like a bolt of lightning.

A demon who could create an artificial night.

This wasn't just a threat—this was a catastrophe.

Tenma's eerie smile widened. "Let's see if you can survive in a world where the sun never rises again."

To Be Continued…

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