"The demon bloodline is the root of evil in this world's fragile order. As the vessel of the Ghost King, you must use this power, move the hand of fate, and complete the missions set by the system."
The system's explanation was simple and absolute. Along with the voice, a glowing list of tasks unfolded before Muzan's eyes.
Main Quest: The Millennium Ghost King
As the origin of all demons, you must bring chaos to the world and become the embodiment of evil.
"The night belongs to demons."
Create subordinates.
Let them move freely.
Hunt humans.
Do not destroy the Demon Slayer Corps that will appear in a hundred years.
Main Quest: The End of the Ghost King
After a thousand years, fight to the death with the chosen one of the world and his companions. Will the world belong to demons or humans?
Side Quest: Establish the Twelve Kizuki
Form the Twelve Demon Moons — the most powerful demons under your command. The Upper Moons shall reign supreme.
Three missions appeared on the empty list.
"So these are my roles," Muzan murmured. "System, what happens if I refuse?"
"If the host rejects the mission, all memories will be erased, and the system will seek a new candidate to fulfill the task."
The answer was as Muzan expected — nothing in the world comes without cost. Even miracles have a price.
"…Fine. But first, let's test this body and see what it can do."
Muzan turned from the glowing screen and approached the corpse of the doctor who had given him new life. Placing his right hand upon the body, he willed the new ability to activate.
A dark light gathered in his palm, forming a small black sphere. In an instant, it expanded, wrapping the corpse completely. The next moment, the sphere vanished into his hand like smoke.
From within his chest, a black core pulsed faintly. Threads of shadow reached into his heart, spreading through his blood and limbs. A strange, burning energy filled him.
"This feeling… incredible."
The hunger within him eased slightly, and his body felt stronger, more stable. His cells sang with life.
"Now then… all that's left is to wait for nightfall."
He glanced toward the setting sun and stepped back into the darkness, waiting.
Three hours later, night descended.
Bathed in moonlight for the first time in years, Muzan looked up at the sky, breathing the cool air. Every nerve in his body felt alive. For more than ten years, he had lived as a frail invalid. No one visited this lonely courtyard except the servants who brought him food. His parents had long moved on, raising a healthy new heir, forgetting the sickly son who should have died long ago.
Strangely, Muzan felt no bitterness — only rebirth… and an overwhelming malice.
"…Time to hunt."
Without effort, he leapt over the two-meter wall surrounding the estate, landing silently on the narrow top before disappearing into the darkness.
Moments later, fire broke out in the small courtyard. The flames spread quickly, devouring the wooden house until it was completely swallowed. By the time the servants noticed, it was far too late to stop.
Muzan Kibutsuji had vanished — leaving behind only ashes and the illusion of his death.
Updated Status:
Name: Kibutsuji Muzan
Race: Demon King
Abilities:
Rapid Regeneration — A
Body Modification — EX
Creation of Subordinates — S+ (Energy gained by subordinates feeds back to the master)
Blood Demon Art — Evolves by consuming energy as needed
Flesh Assimilation — Can absorb and merge with living beings, structures, and even plants
Shadow Legion Summon
Devour — Absorb energy from lifeforms
Blood Memory — Read memories from consumed blood
Alignment: Chaotic Evil
Power Level: Near-Perfect Being
This was an age of endless war.
The common people starved — without food, without shelter.
Life was cheap, worth less than a bowl of rice.
The nobles lived in luxury, draped in silk, drowning in wine, feasting while the poor bled for their comfort. Muzan watched this world from the shadows — the cruelty, the imbalance — and felt nothing but disgust.
Sometimes, out of curiosity, he would gift his blood to certain humans, watching them transform into demons. Most lost their reason immediately, devouring their loved ones before turning on strangers. Muzan thought he would hate such creatures, but instead, he found them amusing. Their failure only proved his superiority.
He learned that a newborn demon could easily overpower several grown men. The more they fed, the stronger they became — until they reached their limits.
But those who couldn't resist their hunger were useless to him. They were weak, broken tools.
He ignored them, letting them hunt freely. Over time, in war-torn lands, stories began to spread.
Whispers of creatures that fed on human flesh.
Rumors of a man — a demon — who created them.
The legend of the Man-Eating Ghosts was born.
Time passed — decades, centuries.
For humans, sixty years was a lifetime.
For Kibutsuji Muzan, it was a moment.
Nearly three hundred years had slipped by since his awakening.
During that time, he wandered across Japan, creating demons and commanding them to search for a mysterious blue flower. Each one was cursed — forbidden to speak his name, forbidden even to think it.
"Search for the Blue Spider Lily," his voice echoed in their minds.
Those who tried to defy him — who even thought his name — met instant, violent death.
To become a demon meant to lose humanity, to live only in the night, forever hunting the living.
Yet the rewards were tempting: strength beyond belief, a body that healed any wound, and a life that never ended.
Muzan had lived over three centuries and still wore the face of a sixteen-year-old boy. To his followers, he was both god and terror.
Not everyone survived his blood. Many arrogant fools burst apart the moment his essence entered them. But over the centuries, more than seven hundred demons had survived his experiments — some strong, others pitifully weak.
And that number did not include those who were transformed indirectly by other demons with Muzan's permission. Their strength was limited, but their numbers grew.
For three hundred years, Kibutsuji Muzan — the Demon King — had walked in the darkness, feeding, devouring, evolving. His cells pulsed with infinite life.
And beneath the moonlight, the true age of demons had only just begun.