It was a gray, backward town—dull compared to the wider continent.
Yet, despite that, the nights were always indulgent. After a long day, when body and mind were exhausted, people sought rest, craving release from the tension that weighed on them.
Even this bleak little town was no exception.
Neon lights colored the streets, laughter echoed through the night market, and even the remote alleys buzzed faintly with life.
But at this moment, in one such alley, stood someone out of place.
A boy.
A teenager dressed in a shabby, gray-white cloth suit. His bright crimson pupils glowed like twin rubies, his body thin, his skin pale as if untouched by sunlight. His face twisted faintly with excitement.
Anyone who saw him would think: this is not a normal human being.
"It's true… I really am normal!"
The boy's name was Mammon. His crimson eyes stared at his own hands, trembling as he felt the power gathering in his fists. For the first time, he could not contain himself.
Normal. He was finally normal.
For sixteen long years, he had lived a half-life, always on the verge of despair, so often driven to thoughts of suicide. He was not like other people—his body had betrayed him since birth.
Born with congenital weakness, Mammon entered the world with death already clinging to him. His heart had even stopped briefly in the delivery room. But somehow, out of sheer instinctive will to live, he clawed his way back.
Even so, his body remained fragile. By the age of ten, he could no longer even stand on his own, confined instead to a wheelchair. Walking—something ordinary people took for granted—was a dream far out of reach.
But now… now he was free.
He clenched his fists and felt strength surge through him. Only minutes ago, he could not even close his hand.
"The system… it's real! My body really is normal!"
Energy thrummed through every vein, and a wild grin stretched across Mammon's pale face.
It had happened just after his sixteenth birthday. A voice had echoed in his mind, gifting him a system. And with it, a character template.
Not just any character. The final boss of Demon Slayer: Muzan Kibutsuji, the infamous cowardly, greedy, utterly evil demon king.
Mammon remembered him vividly from his past life. Fans mocked Muzan relentlessly—dreaming of forcing him into the sun, making him drink wisteria tea, or tormenting him with absurd punishments.
But none of that mattered. What mattered was this: Mammon now possessed all of Muzan's abilities.
A healthy body.
The very thing he had yearned for, the thing he had dreamed of in his darkest, most powerless moments. Only those who had lived in the abyss of frailty could understand what this meant.
"Hahahahahaha!"
Mammon's fists slammed together as he threw his head back and laughed madly, tears streaming unbidden down his pale cheeks.
Health. Strength. Freedom.
Sixteen years of despair shattered in an instant.
"Blood… curses. Demon arts…"
He whispered to himself, brushing away his tears, savoring the reborn vessel he now inhabited. This wasn't just Muzan—this was Muzan at his peak. Complete. Limitless.
And above all… the blood curse.
The source of every tragedy in Demon Slayer. The very power that birthed demons.
Unlike ordinary spirits, these demons fed on flesh and blood, immortal and unyielding, each wielding terrifying supernatural powers. And at the root of it all was Muzan's blood. With it, humans could be twisted into monsters. Their strength depended on how much blood was granted, though their growth had natural limits.
Mammon's crimson eyes gleamed."That means… I too am qualified to chase power."
The corners of his mouth curled into a dark smile, cold light flickering in his gaze.
Sixteen years of weakness had warped him. He had stared into despair too long, his spirit tempered only by the twenty extra years of maturity he carried from a past life.
He was no longer ordinary.
And this world… this world was far from normal.
At that moment, three staggering figures emerged at the end of the alley—drunken men clutching bottles, cursing loudly.
One of them stumbled right into Mammon's shoulder. But instead of knocking the thin boy aside, the drunk rebounded as if he'd crashed into iron, sprawling onto the ground with a yelp.
"Dammit! You little brat—watch where you're going!"
The yellow-haired drunk staggered upright, clutching his side. The wine bottle slipped from his hand, shattering as anger flared in his bloodshot eyes.
"Sorry," Mammon said flatly, crimson gaze cold. "But I haven't moved from this spot."
He had met plenty of men like this before—loud, unreasonable, full of nothing but noise.
"What was that, you bastard?" the drunk snapped.
But before he could lunge, his red-haired companion scoffed. "Forget it, Red. Don't waste time with this half-dead kid."
The words sank deep. Mammon's eyes darkened instantly, crimson irises sharpening into slit pupils, beastlike and cold.
"Yeah," Yellow sneered, circling Mammon with a mocking grin. "Look at his sickly face. Probably won't last another month. Hahaha!"
Mammon lowered his head slightly, voice flat and toneless."Do I… look half-dead to you?"
The drunk laughed louder. "Don't you? Look at yourself—already one foot in the gra—"
He never finished.
With a sudden, grotesque shift, Mammon's left arm erupted into twisted flesh. His palm split open into a gaping maw lined with fangs, and it clamped down on the drunk with crushing force, lifting him high into the air.
"Aaaaagh!"
The man's scream tore through the alley as blood sprayed. The crimson liquid dripped steadily from Mammon's monstrous hand.
The others froze, horrified, unable to comprehend the nightmare before them.
Crunch!
The sound of tearing flesh filled the alley. The drunk's body went limp.
Blood rained down.