Mammon's lips curved slightly as he watched with interest the large rat writhing and convulsing painfully on the ground.
His blood seemed to work on creatures that weren't human.
If that were the case, would it also work on the monsters from other dimensions that invaded this world?
Or even those beings who arrogantly called themselves higher lifeforms?
If so, he could use the Blood Curse to create a race of terrifying demons.
"…The Twelve Kizuki."
Mammon glanced at the three rats that were trembling violently.
"That would be quite interesting."
Without looking back, he walked away from the alley with calm, leisurely steps.
The amount of blood he had injected into the brown-haired woman had been enough to make even her body explode.
Those small rats naturally had no chance of surviving.
Even though the woman had already died and only a small amount of Mammon's blood remained in the flesh the rats had eaten—
And even though the rats had ingested even less—
Their bodies were small, and their genetics were far inferior to humans.
Surviving the mutation would be extremely difficult.
Of course, even if one rat somehow managed to endure the corruption of his blood, Mammon didn't really care.
Because he possessed absolute authority over the life and death of all demons.
Bang!
Bang!
Not long after Mammon left, two sounds like balloons bursting echoed in the silent alley.
The place became eerily quiet, filled only with the heavy smell of blood.
But soon—
A pair of blood-red vertical pupils suddenly opened.
They were filled with brutality and wildness.
…
Just as Mammon exited the alley, his footsteps paused for a moment.
Then he continued walking normally.
"Heh… one of them actually survived."
"That's quite impressive talent for a rat."
A faint smile appeared on Mammon's pale face.
He could clearly sense it—
Inside that alley, the second demon of this world had just been born.
A Rat Demon.
Mammon could naturally sense any demon he created.
That filthy rat had actually survived the erosion of the Blood Curse.
It surprised him a little.
But it didn't really matter.
He wondered how far this Rat Demon might eventually climb.
Mammon dismissed the thought and began walking toward his home.
Along the way, the streets were lively with bright lights and bustling crowds.
Mammon, dressed in his worn clothes with a calm expression, seemed completely out of place in such prosperity.
This parallel world was originally not much different from the world in Mammon's previous life.
There was only one difference.
Dimensional invasion.
After the dimensional barrier shattered, the planet—Azure Star—began to undergo strange changes.
Rather than changes…
It would be more accurate to call it evolution.
The planet's overall size was quietly expanding for unknown reasons.
The land area was increasing as well.
Several years had already passed since the dimensional invasion began.
Humanity had long since abandoned its old conflicts and formed the Human Strategic Alliance.
Because without unity, humanity would slowly go extinct against the endless strange monsters and dimensional invaders.
At the same time, as the world evolved, humans also began to evolve.
These people were called Evolvers.
Or more commonly—
Ability Users.
They were the main force capable of defending humanity against monsters.
After several years of struggle, the situation had finally stabilized somewhat.
Humanity had barely survived the first wave of dimensional invasion, gaining a brief period of safety.
But the direction of the world had already changed completely.
Modern society had transformed into something entirely new—
A survival-of-the-fittest ecosystem.
The strong ruled.
Ability users had become a class above ordinary people.
Because only ability users could truly protect humanity.
Technology?
That was already a thing of the past.
Two years ago, from the deepest trench of the Atlantic Ocean emerged a monster hundreds of meters tall.
It was classified as an Epic-Level Disaster.
A giant squid.
Even after deploying humanity's strongest nuclear weapons, the monster could not be killed.
In the end, dozens of ability users combined with enormous firepower barely managed to drive it back into the ocean.
It was never actually destroyed.
Human society had maintained a fragile peace for about a year.
Occasionally monsters still attacked cities, but they could at least be defended against.
Humans were remarkably adaptable.
After the initial chaos, people gradually adapted to this new world.
But the social divide between ability users and ordinary humans had become impossible to remove.
They lived under completely different conditions.
"I wonder… what level of ability user I count as now."
Leaving the noisy night market behind, Mammon slowly raised his slender hand.
A thoughtful light flickered in his eyes.
Strictly speaking, the power level of Demon Slayer was not particularly high compared to many other fictional worlds.
In fact, it could even be considered relatively low.
However—
Kibutsuji Muzan's abilities were undeniably extremely broken.
His blood functioned almost like a virus.
The Blood Curse could turn others into demons.
And if the new demon had enough talent, they could awaken their own Blood Demon Art, a special supernatural ability.
Kibutsuji Muzan was the ultimate boss of Demon Slayer.
Even in the original story, the protagonists paid an enormous price to finally destroy him.
But Mammon still couldn't determine something.
If he now possessed Muzan's peak template—
What level of power did that place him at in this world?
"…Sunlight."
That was the most important issue.
Mammon frowned slightly and looked up at the streetlights above him.
The artificial light caused him no discomfort.
But all demons created by Muzan shared one fatal weakness—
They feared sunlight.