The sun was rising by the time Tanjiro, Saitama, Nezuko, and a still half-conscious Zenitsu arrived at the Demon Slayer headquarters. After the "incident" with Gyokko, crows had flown at full speed to deliver the report — but no one actually believed what they heard.
Upper Moon 5 defeated in a single slap.
When the Demon Slayer Corps' top swordsmen, the Hashira, gathered to hear the details, most of them thought it was some kind of bad joke. The air was tense as the Hashira sat in their designated spots, waiting for the mysterious "hero" to arrive.
Rengoku's bright laughter broke the silence. "A bald man defeating an Upper Moon with his bare hands? What a fascinating tale! I must meet this man immediately!"
"Sounds like nonsense," Sanemi scoffed, arms crossed. "If someone that strong existed, we would've heard of him already."
"Maybe he's a hidden master," Mitsuri said, her eyes sparkling with curiosity. "Or a retired Hashira!"
"Or maybe," Obanai muttered darkly, "he's the real threat, disguised as a fool."
As the Hashira debated, the doors slid open — and in walked Saitama, scratching his head, followed by Tanjiro. Nezuko peeked out from her box, her curiosity piqued. Zenitsu stumbled in behind them, his eyes still half-closed from all the stress.
The Hashira stared.
A bald man in a skin-tight yellow suit, red gloves, and a white cape.
"This… this can't be real," Sanemi muttered.
"Who cut off all your hair?" Tengen asked, leaning forward. "Was it part of a tragic backstory? A failed romance? A betrayal?"
"No, I just trained really hard," Saitama said, his face blank as ever. "It all fell out."
The Hashira collectively paused, waiting for him to explain further. He didn't.
"Are you… a Demon Slayer?" Muichiro asked, his voice almost sleepy.
"Nope."
"Then what are you?" Giyu's serious gaze locked onto Saitama.
"Just a hero for fun," Saitama repeated.
The room fell into silence again. Tanjiro was sweating bullets, unsure how to explain this walking disaster of a man.
"He really did defeat Gyokko," Tanjiro finally spoke up. "With one slap."
"He's joking," Sanemi spat. "That's impossible."
"Not really," Saitama said, rubbing his neck. "That fish guy was pretty weak. I was hoping for something stronger."
Sanemi's eyebrow twitched. Before anyone could stop him, the Wind Hashira leapt forward, sword flashing. "Let's see how strong you are then, BALDY!"
The blade sliced down — but never reached Saitama. With a lazy flick of his finger, Saitama tapped the flat of Sanemi's sword.
CRACK!
The Nichirin blade shattered into glittering pieces. Sanemi froze mid-air, landing awkwardly as the broken sword clattered to the floor.
The Hashira were speechless.
"What kind of breathing technique was that?!" Mitsuri gasped.
"Breathing?" Saitama tilted his head. "I was just trying not to break your toy."
"TOY?!" Sanemi's veins popped, but even he couldn't deny the truth. His sword — a master-crafted Nichirin blade — had been broken by a casual finger tap.
"Enough." A calm, commanding voice echoed through the room as Oyakata-sama entered, escorted by his attendants. The Hashira immediately knelt.
"So," the gentle leader said, smiling. "You are the man who destroyed an Upper Moon with a single strike?"
"Uh… yeah," Saitama said, glancing around awkwardly. "That was me."
"You are neither a Demon Slayer nor a Hashira, yet you possess unimaginable strength. May I ask why you fight?"
Saitama scratched his head. "Honestly? Just a hobby."
The room was silent again. The entire Demon Slayer Corps was built on sacrifice, revenge, and the burning desire to protect humanity. And this man… fought demons as a hobby?
"I see," Oyakata-sama said softly, his smile never fading. "Then, would you like to join us — even if only for a while?"
Saitama shrugged. "Do I get food and a place to sleep?"
"Of course."
"Then sure, why not."
Just like that, the strongest being in two worlds accidentally joined the Demon Slayer Corps — not for justice, not for revenge, but because the food was free.
As the Hashira tried to process this absurdity, Tanjiro couldn't help but feel both relief and terror. Relief that they had Saitama on their side. Terror because the Hashira still had no idea what kind of chaos was about to unfold with Baldy in their ranks.
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End of Chapter 4