Chapter 27: Hot Springs of Doom – Muzan Arrives

The peaceful air around the hot spring hung heavy with steam, a perfect haven for the weary Demon Slayers. Laughter echoed from both sides of the spring—Inosuke challenging Tanjiro to a contest of "Who Can Hold Their Breath Longer," while Zenitsu tried (and failed) not to faint at the sound of Mitsuri's voice from the women's side.

Saitama simply floated, his bald head reflecting the lantern light like a polished gem. His expression was as blank as ever, yet somehow it radiated contentment.

"This is nice," he mumbled, half asleep.

Suddenly, Nezuko's head popped up from the edge of the spring, her eyes wide. She sniffed the air, her instincts on high alert. Something was wrong—very wrong.

Tanjiro immediately noticed her reaction. "Nezuko? What's wrong?"

Before anyone could answer, the water trembled. Small ripples spread across the surface, and an unnatural chill swept through the air. The once-relaxing steam became thick, suffocating almost, like a presence had infected the air itself.

Then—BOOM!

The ground split apart at the edge of the hot spring, water splashing in all directions. From the earth rose a twisted amalgamation of flesh, tendrils of blood weaving through the air like sinister ribbons. And standing at the heart of it was none other than Kibutsuji Muzan.

He didn't arrive with elegance this time. No subtle manipulation, no quiet intimidation. This was Muzan at war, his crimson eyes burning with fury, his sharp nails already extended into blades of death.

"Muzan!" Tanjiro shouted, leaping from the water, still soaking wet, sword drawn.

Zenitsu screamed, grabbing his towel like it was a holy relic. "WHY IS THE FINAL BOSS SHOWING UP IN THE BATH?!"

Inosuke, completely naked, struck a fighting pose. "BRING IT ON, YOU DEMON LOSER!"

Muzan ignored them all, his gaze locked on one man—the bald, bored-looking man who hadn't even stood up.

"You…" Muzan's voice was venom wrapped in silk. "You are the one responsible for ruining my entire structure…for erasing centuries of effort in a single night."

Saitama scratched his head. "Uh… who are you again?"

A vein bulged in Muzan's forehead. "I AM KIBUTSUJI MUZAN! THE ORIGIN OF ALL DEMONS! THE ULTIMATE BEING!"

Saitama blinked. "Oh. Okay."

There was a silence so awkward even Inosuke hesitated.

Muzan's body expanded, dark tendrils whipping through the air, slicing through rocks and trees alike. The air itself seemed to hum with demonic power, the weight of Muzan's sheer presence pushing down on everyone.

"I will not allow a mere human—no, a bald monkey—to humiliate me!" Muzan roared.

Saitama stood up from the spring, water cascading off his absurdly normal-looking body. He picked up his hero cape and draped it over his shoulders. "You talk a lot."

Before anyone could react, Muzan lunged forward—faster than even Zenitsu could see. His claws aimed straight for Saitama's throat.

SLAP.

Saitama casually swatted Muzan's hand away like a fly. The force of the slap disintegrated Muzan's entire arm, sending a shockwave so powerful it blew the hot spring's fence into splinters.

Muzan stumbled back, clutching his stump. His eyes were wide with disbelief.

"Wha—what are you?"

Saitama rolled his shoulders. "Just a guy who's a hero for fun."

Zenitsu fainted on the spot.

Tanjiro could only gape. Even Nezuko tilted her head like, This is getting ridiculous.

Muzan regenerated his arm almost instantly, but the fear in his eyes betrayed him. No human—not even Yoriichi—had ever struck such effortless terror into his heart.

"This isn't possible!" Muzan shrieked. "You're not a Demon Slayer! You have no breathing techniques! You're not even marked!"

Saitama sighed. "Don't need all that."

In a single instant, he disappeared from sight, reappearing directly in front of Muzan.

"Consecutive Normal Punches."

A flurry of strikes, too fast for even Tanjiro's enhanced senses to follow, hammered into Muzan's body. Each punch created a sonic boom, shaking the ground and sky alike. Trees were uprooted, boulders split, and the entire hot spring exploded into a geyser from the sheer force.

Muzan's body disintegrated and reformed repeatedly, regeneration struggling to keep up. His screams echoed across the mountains.

"I—I am immortal! I cannot be defeated!" Muzan shrieked.

Saitama cracked his neck. "That so?"

He raised a single fist, and for the first time, his serious expression surfaced.

"Serious Punch."

The punch didn't even touch Muzan directly—just the shockwave alone ripped through his body like paper, scattering him into millions of blood particles.

For a moment, silence reigned.

Tanjiro, Inosuke, and Nezuko stood there in stunned disbelief, their bodies drenched, hair sticking to their faces from the destroyed hot spring. Zenitsu, still unconscious, floated face down in the steaming puddle that remained.

"Is… is it over?" Tanjiro asked.

Saitama glanced around. "Huh. That felt a bit too easy."

Somewhere, in the scattered particles of Muzan's shredded form, a faint whisper echoed:

"This… this isn't over…"

But Saitama had already turned away. "Man, I really wanted to relax in that spring. Now it's ruined."

---

The hot spring was gone.

Muzan was (mostly) destroyed.

And the legend of the Bald Slayer spread across the Demon Slayer Corps like wildfire.

But this story… was far from over.

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End of Chapter 27