Ren Kuroda still had no idea how many creatures like the Four-Limbed Oni roamed this world. But one thing was clear: without proper weapons, killing a hundred of them would be almost impossible.
After leaving the village, Ren began his demon-hunting journey alone.
Thanks to his sharpened senses—especially his keen sense of smell—and the knowledge that these creatures only came out at night to prey on villagers, tracking them was surprisingly easy. And now that he finally had a weapon, dispatching demons of equal or lesser strength became almost effortless.
But effortless didn't mean simple.
These demons were absurdly resilient. Even when Ren tore them apart, they refused to die cleanly. After extensive trial and error, he settled on the most reliable method: carve them into pieces, then let the rising sun finish the job.
Through countless battles, Ren also discovered something reassuring:his earlier fears about being swarmed were unnecessary. These demons always acted alone. Never in groups. Apparently, that was simply their nature.
As he traveled and fought, Ren gradually pieced together fragments of knowledge about this world. Unfortunately, even with his enhanced senses, his hunting speed was still far too slow for his liking.
At his current pace, killing a hundred ordinary demons within two years wouldn't be difficult.
But then he learned something unsettling—information extracted from trembling, half-dying demons begging for their lives.
The "Twelve Demon Moons."
According to these creatures, the Moons were the twelve strongest subordinates of the Demon King himself. If low-level demons were cannon fodder, the Twelve Moons were walking calamities. Monstrous in strength. Terrifying in reputation.
Ren knew immediately: without a specialized weapon, facing one of them would be suicide.
As for the Demon King… every time Ren asked, the demons broke into hysterical terror. Even as they died, they refused to utter a single word. Not even a hint.
So Ren continued to wander from region to region—not just to fulfill his mission, but also to find clues about the mysterious "Demon Slayer Corps."
Until that day.
Deep in a snow-covered forest, Ren picked up the scent of demons again… mixed with the coppery tang of fresh blood.
Like always, he followed it without hesitation.
At first, he assumed another villager was under attack.
But when he reached the source, the scene before him made him pause—then raise an eyebrow in interest.
In the snow-dusted clearing, a boy and a demonified girl were facing off against a young man holding a blue-hued longsword.
Ren instantly sensed it: the girl had been turned into a demon. Yet instead of attacking, she was shielding the injured boy behind her.
Interesting…A demon retaining her sanity? No—more than that. Protecting a loved one.
A bond strong enough to break the curse? That's new.
Ren crossed his arms, watching from atop a tree branch.Sure, the girl's physique had been enhanced by her transformation—but the swordsman was no pushover either.
And the boy?Ren snorted.
"He's weak enough to be a liability. Completely defenseless. If she lost control for even a second, he'd be dead."
He tilted his head.
"…Should I step in?"
After all, the man with the blue sword wasn't wrong.
"The weak have no rights. No choices. They survive only under the protection of the strong. If you want respect, you must earn it through strength. That's reality."
In any world—human or demon—the law of survival ruled all.
To protect what you cherish, you must possess the power to do so.
The man's words drove that truth deep into the heart of the kneeling boy—Tanjiro. His trembling shoulders said it all: he understood now just how cruel the world truly was.
If he had been strong enough, his family wouldn't be dead.His sister Nezuko wouldn't be in this state.
The swordsman—Tomioka Giyu—wasn't trying to torment the boy. He simply wanted him to face reality.
With Tanjiro's current weakness, there was no possible way he could keep a demon-turned sister at his side. Even if Nezuko retained a shred of reason now… no one knew when that shred would vanish.
And when it did?A demon needed only a moment to devour someone helpless.
So Giyu's conclusion was simple:he hadn't planned to spare Nezuko from the start.
Ignoring Tanjiro's cries, Giyu raised his Nichirin Blade, preparing to strike the final blow.
The blade flashed downward—
CLANG!
A metallic ring split the air as another longsword intercepted the killing strike.
A figure landed between Giyu and Nezuko in a blur of motion.
"I'm sorry," Ren Kuroda said casually, "but I really admire this brother-and-sister pair. I can't let you kill his sister."
Ren pushed against Giyu's blade, forcing it aside.
"I agree with what you said earlier—strength is everything. But tell me, how do you know this boy won't become someone worth respecting because his sister becomes stronger?"
Giyu's eyes widened slightly.
He hadn't sensed this newcomer at all.
For a Demon Slayer, that was a humiliating oversight. If Ren had intended to kill him instead of defend the girl, he'd already be dead or maimed.
Giyu's frown deepened as he studied Ren.
The aura around him was… off.Not human.Not fully demon either.A strange, balanced hybrid—demonic power without the stench of bloodthirst.
Ren used the moment of Giyu's distraction to pivot sharply, delivering a powerful downward slash that forced him back.
With one smooth movement, he grabbed Nezuko and tossed her toward the recovering Tanjiro, who caught her with shaking arms.
"You're with the Demon Slayer Corps, right?" Ren asked, tapping his shoulder with his worn longsword. "So that's the famous Nichirin Blade. The one that supposedly cuts demons like paper."
He grinned.
"Looks impressive. Why don't we spar a little? I'm protecting these siblings today. And honestly… your sword interests me."
Ren slid into a stance, blade raised, his eyes gleaming with anticipation.
The snow around them stirred, the air tightening in anticipation of the clash.