Ren Kuroda had never formally trained in any martial art, but it didn't matter. His speed, strength, and reflexes utterly eclipsed the monster before him. Against the four-limbed demon, Ren wasn't simply winning—he was overwhelming it.
The creature's resilience was remarkable. No matter how many times Ren shattered its bones or ripped apart its limbs, the thing would knit itself back together. Without a special anti-demon blade or sunlight, he couldn't kill it.
But suppress it? Humiliate it?
That was easy.
At first the four-limbed demon had been smug, even arrogant. He had assumed Ren was like him—just another demon prowling for a midnight feast. A rival, perhaps, but nothing worth fearing.
Especially not when the demon himself had devoured far more humans than most of his kind.
In this world, a demon's power grew with every human it consumed. Ordinary low-level demons picked off families, lone travelers… small prey. But this one, relying on monstrous speed and agility, raided entire villages. Night after night. Dozens of victims at a time.
By now, the four-limbed demon was so confident in his strength he believed he was on the verge of awakening his own Blood Demon Art—a power reserved for upper-ranked monsters.
With that pride, he had dismissed Ren entirely when first seeing him.
But once the fighting began, that confidence shattered like brittle ice.
Even after gorging on so many humans, the demon was the one who lost an arm on the first exchange. His prized mobility—leaping, sprinting, bounding on all fours faster than a human could blink—was useless.
He couldn't even see Ren move.
The half-demon boy appeared and disappeared like a ghost, suddenly behind him, snapping his neck—or in front of him, driving a heel into his spine. Limbs broke. Bones crumpled. Again and again.
Yes, he would regenerate. But immortality wasn't the same as being immune to pain.
After only moments of battle, the four-limbed demon understood the truth:
He wasn't fighting an equal.He wasn't even fighting something on the same level.
This thing—this young man—was a monster among monsters.
Is he… one of the Twelve Demon Moons? the demon wondered in horror.The Twelve served directly under the Demon King, each wielding a Blood Demon Art of nightmarish power. But even among them, none relied purely on physical strength the way Ren did.
No Blood Demon Art.No demonic techniques.
He was beating the four-limbed demon with nothing but brute force.
When the demon's head was crushed for what felt like the twentieth time, he finally cracked.
He begged.
"B-Brother—brother! We're both demons, right? You're stronger, I admit it! But you can't kill me, even if you wanted to… So why fight?" he pleaded, pinned under Ren's foot. "If you want to feast on this village, take it. I'll go elsewhere. Humans—there are so many of them. We don't need to fight over a few scraps! If we keep going like this, the sun will rise soon—then we'll both burn!"
The demon had tried to flee earlier—many times, actually—but each attempt ended the same: Ren caught him effortlessly and beat him back into the snow.
Misreading Ren's motives entirely, the demon assumed his earlier provocations were the reason for the relentless violence. Now, with sunrise approaching, he thought surrendering might save him.
Wrong.
Ren pressed his heel down harder, grinding the demon's skull into the snow.
"Who told you I'm one of you cannibalistic monsters?" Ren said coldly. "I'm a demon, true—but not like you. You creatures can't even function without devouring flesh and blood. Don't lump me in with your kind."
He kicked the demon again, sending its head bouncing across the ground before it slowly began regenerating once more.
"And sunlight?" Ren scoffed. "That's your problem, not mine."
This wasn't cruelty for cruelty's sake. Ren wasn't enjoying himself.
He was experimenting.
Every time he killed the four-limbed demon, the regeneration took just a bit longer. The healing wasn't limitless. It drained something—energy, essence, whatever demons in this world used as fuel.
If he killed it enough times in rapid succession…He should be able to kill it for good.
As dawn approached, the faint glow on the horizon grew brighter. The four-limbed demon's panic grew too.
"No—no, no, no!" it shrieked, thrashing beneath Ren's foot. "Let go of me! Let go! The sun—THE SUN!"
It knew better than anyone: sunlight was pure death.Even the Twelve Demon Moons couldn't survive it.Even the Demon King himself could not endure the sun's touch.
To a demon of this world, it was the one and only absolute weakness.
Ren's foot held firm, as heavy and unmovable as an iron stake.
To the four-limbed demon, Ren Kuroda was a lunatic. A complete maniac.
What kind of demon isn't afraid of sunlight!?The Demon King had spent centuries trying to overcome that weakness, and even he failed. If any random demon like Ren could walk in daylight, what would that make their king? A joke?
The demon felt bitter regret in his final moments.Why had he taunted this boy?Why hadn't he run faster?For a stupid bit of pride, he had forfeited his life.
The sun's first rays pierced the clouds, a golden blade slicing across the sky.
The moment sunlight touched him, the demon beneath Ren's foot let out a scream unlike anything Ren had ever heard. Smoke surged from his body. His feet crumbled into ash. Flesh disintegrated. Bones cracked and evaporated.
Even as he died, the four-limbed demon stared up at Ren with bulging, disbelieving eyes.
Why…? Why aren't you burning too?
Because Ren stood there, illuminated by morning light, completely unharmed—snow glistening in his hair, expression calm.
The demon died wondering whether the very concept of "demon" had just been rewritten before his eyes.