The corners of Mammon's mouth curved faintly as he stared at the oversized rat convulsing in agony on the ground. His crimson eyes shimmered with curiosity.
His blood worked—even on creatures that weren't human.
Did that mean it could also affect those monsters spilling out from other dimensions? The so-called higher beings?
If so, he could create his own demon race—creatures born of blood and curse.
"The Twelve Kizuki… That's going to be interesting."
Mammon cast one last glance at the three trembling mice, then turned and walked away without looking back.
The blood he had poured into the brown-haired woman had been so potent that it tore her body apart. How could these feeble rats possibly endure it?
Even the scraps they devoured carried little blood—yet for their tiny frames, even that was overwhelming. Their genes were far inferior to humans; adapting to his curse was almost impossible.
Almost.
If a rat truly managed to survive… Mammon didn't mind. He had absolute dominion over life and death when it came to demons.
Boom.
Boom.
Not long after Mammon's departure, two wet pops echoed like bursting balloons. Then silence returned to the alley, broken only by the stench of blood.
But soon—
A pair of blood-red, slit-like pupils flickered open in the dark. They glowed with savage, primal hunger.
Just beyond the alley, Mammon paused. A flicker of awareness touched his mind, then he resumed walking as if nothing had changed.
"Heh… if even a rat can survive, then that's some decent potential."
A pale smile curved across his face. He knew it—at that very moment, the second demon of this world had been born.
A rat demon.
Every demon he created was bound to him. Their existence pulsed faintly in his consciousness.
That filthy sewer rat had endured the blood curse. It surprised Mammon, though not enough to trouble him. He was more curious than concerned.
How far could a creature like that climb?
The thought vanished as quickly as it came, and Mammon continued toward his dwelling.
The streets glittered with red and green lights, alive with laughter and chatter. But Mammon, draped in his shabby gray cloth, moved calmly through it all, a pale shadow at odds with the city's prosperity.
This world… it wasn't so different from the one in his memories.
Except for one thing: the dimensional invasion.
When the barrier between worlds shattered, Aquamarine underwent changes too vast to call simple "change." It was evolution.
The land itself expanded for unknown reasons, as if the very planet were stretching.
A year had passed since that first invasion. Humanity, forced to abandon its divisions, formed a global alliance. Without unity, Aquamarine would have already fallen to the countless monsters spilling through the rifts.
And as the world evolved, so too did humanity.
"Evolutionaries"—those touched by change—emerged. Known simply as "Ables," they became the frontline against dimensional horrors. Their powers were humanity's only real defense.
After years of chaos, the tide finally steadied. Humanity had survived the first wave, buying itself a fragile peace.
But the world had already transformed into something new.
The law of the jungle ruled now.
The strong thrived. The weak fell.
Ables stood above the rest, exalted, while ordinary humans were left to scrape by. The divide between the two could never be undone.
Technology? That belonged to the past. Humanity had already learned the futility of machines when, two years ago, a colossal statue-like squid rose from the Atlantic depths—an "Epic Disaster," the King Squid.
Nuclear fire had done nothing. Not even humanity's most devastating weapons left a mark. Only through the combined might of dozens of Ables and countless weapons of war had the beast been forced back into the sea.
Not slain. Simply driven away.
For the past year, society had known an uneasy harmony. Cities still suffered monster raids, but they were contained. Humanity adapted, as it always did.
But in this new world, only power mattered.
Mammon drifted from the night market into a quieter street. He lifted his pale, slender hand, studying it with thoughtful eyes.
"I wonder… what level am I considered now?"
By raw measure, the combat strength of Demon Slayer's world was unimpressive. In the grand scale of two-dimensional works, its power system ranked low.
But Muzan Kibutsuji was different. His blood was a virus, a curse—capable of birthing ghosts that, given talent, could wield terrifying blood demon arts. Even fledglings could awaken unique abilities.
Muzan had been the Demon Slayer world's apex predator. Even the heroes paid a terrible price to bring him down.
And now, Mammon held Muzan's complete template. His peak.
But what grade did that make him here, in this dimension-torn world?
"…The sun."
Mammon's gaze flicked upward to the streetlamp overhead. The glow bathed his pale skin, but he felt no discomfort.
Yet the weakness remained. Muzan's curse, and the curse of all demons:
The fatal fear of the sun.