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

The sun had just started to rise, painting the sky with soft hues of orange and pink. The Demon Slayer Corps headquarters, which had stood as a fortress for generations, now felt strangely quiet. Without the constant threat of demons, it was like a heavy curtain had been pulled back, revealing a world full of possibilities — and uncertainties.

Saitama stood on the edge of the training field, arms crossed, cape fluttering gently in the breeze. Genos stood beside him, his glowing eyes scanning everything with sharp precision.

"You sure you wanna stick around, Sensei?" Genos asked, his voice respectful but concerned. "We've already detected several interdimensional fluctuations near City Z back home. Your absence is causing instability."

Saitama yawned. "Eh, it's fine. It's probably just another mosquito or something."

Genos, as usual, took the comment far more seriously than intended.

"Understood. I will remain on high alert."

---

The Hashira's New Purpose

The Hashira gathered near the central hall, trying to figure out what came next.

"With demons gone, do we disband?" Mitsuri asked, twirling a strand of pink hair nervously. "I mean… this is good, right?"

"Of course it's good," Sanemi snorted. "But we're still warriors. If not demons, we'll deal with whatever else comes crawling out of the woodwork."

Kyojuro's eyes sparkled. "Indeed! We shall train even harder! And with Saitama-dono here, we may discover entirely new techniques!"

Muichiro, usually lost in his own head, actually spoke up. "I… felt something strange last night. Like the world wasn't stable."

The others glanced at him, surprised.

"Is that connected to Saitama-san?" Shinobu asked curiously.

"Possibly," Muichiro muttered.

---

The Crack Grows

High above the mountains, the faint crack that had formed in the sky after Muzan's defeat had spread wider, like a spider web crawling across glass.

Something was pushing against it. From the other side, a voice whispered, too faint to understand, but dark and chilling. It wasn't a demon's voice. It was something… older. Forgotten.

---

Training Arc? Or Something Worse?

Back at the training field, Saitama was holding a massive log with one hand, casually lifting it above his head while the Hashira watched in awe.

"Sensei, should I set up a training regiment for them?" Genos asked, already mentally designing killer workout programs.

"Nah," Saitama said. "Let's keep it simple."

He set the log down and cracked his knuckles. "Let's spar."

The Hashira exchanged glances.

"Spar? With you?" Giyuu asked, raising an eyebrow. "That feels… dangerous."

"Don't worry, I'll hold back," Saitama said with a shrug.

Zenitsu was already shaking. "H-h-hold back? You split the sky last time you sneezed!"

"All the more reason to train!" Rengoku beamed. "We shall forge our bodies to withstand such power!"

---

First Sparring Match - Saitama vs. Inosuke

Inosuke stepped forward, dual swords drawn, wild grin on his face. "Finally! A worthy fight! Let's go, BALDY!"

Saitama sighed. "Another guy calling me bald…"

Inosuke charged like a boar possessed, swords spinning wildly — but before he could even blink, Saitama's finger flicked him gently on the forehead.

BOOM!

Inosuke was launched across the field, landing in a bush upside down.

Everyone sweatdropped.

"Too much?" Saitama asked.

The Hashira silently nodded.

---

The Rift Shudders

While they trained, the crack in the sky pulsated once more. This time, a faint shape could be seen through the rift — a hand, covered in shadow and scales, reaching through.

The sky darkened briefly, and even Saitama paused, his eyes narrowing slightly.

"Sensei?" Genos asked, sensing the shift.

Saitama smiled lazily. "Looks like we've got a new visitor. About time things got interesting again."

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End of Chapter 47

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