Fragments of words echoed in Tsukihiko's mind, a chaotic mess of sounds that felt like a nightmare. Sailor uniform. Maid outfit. Taisho era.
He didn't understand what they meant. Countless images flashed through his consciousness like an old, damaged film reel before flickering out and vanishing completely. What came next was pain—a deep, crushing agony that spread through his entire body, making it impossible to even draw a breath.
More words flooded his mind, sharp and clear this time.
Tsukihiko.
Demon King.
Muzan Kibutsuji.
In that single, overwhelming moment, everything clicked into place. Tsukihiko, a man who had believed he was moments away from dying of cancer, finally understood what had happened.
He had been reborn.
Not just reborn, but he had taken over someone else's body. He had become an entity named Muzan Kibutsuji.
The name was instantly familiar. Muzan Kibutsuji, the ultimate villain from the story Demon Slayer. The infamous "Scum Boss" who was known for his arrogance, for firing his subordinates during meetings, and for throwing powerless tantrums when things didn't go his way.
But he was also the most powerful being in this world. He was the Demon King, the ruler of all demons, with five brains and seven hearts. He could regenerate any part of his body in an instant, making him practically immortal. It was no exaggeration to say that, except for his weakness to sunlight, he had achieved the dream of eternal life.
Tsukihiko, who had spent his final days as a terminal cancer patient, could never have imagined this. He had been waiting for death, but instead, he had been given a new life. From this moment on, he was the strongest Demon King in the world of Demon Slayer.
He was the ruler of demons.
He was Muzan.
But deep down, he still preferred to be called Tsukihiko.
His new eyes snapped open with a quiet whoosh. They were the color of rubies, and in them, he could see the reflection of his surroundings. The terrible pain and weakness that had haunted him during his illness were completely gone. In their place, there was only one feeling: power. An immense, overwhelming power that flowed through every part of his new body.
A small smile touched Tsukihiko's lips. "From now on, I am Tsukihiko... and I am also Muzan Kibutsuji."
As a man who had been knocking on death's door, his desire to live was stronger than anyone else's. He had been powerless to stop his illness, but now, things were different. He had been given a second chance by becoming the most feared being in this world. Since he was here, he decided he would make the best of it.
From this day forward, the entire world would dance to his tune.
The moment he had that thought, Tsukihiko felt something strange. It was as if countless invisible tentacles were extending from his mind, spreading out in every direction. In an instant, information flooded his senses. He could feel the presence of every single demon in the world that had been created with his blood. He knew where they were and what they were doing. It was all clearer than anything he had ever experienced.
"So... this is power," he whispered to himself, a strange smile spreading across his face.
There's an old saying that when a man holds a weapon, the urge to use it is born. When a person is fighting just to survive, they will cling to any hope they can find. But when that same person is given immense strength and a powerful advantage, they won't hesitate to strike down anything that stands in their way. A common man's anger might cause a small amount of bloodshed. But the anger of a king—or a Demon King—could rewrite the world.
And now, he was Muzan Kibutsuji, the strongest villain in this story.
"Eternal life is a wonderful thing," Tsukihiko thought, "but what's the point if I have to hide in the shadows like a rat, never able to see the sun?" He knew the story well. "More importantly, every villain eventually faces their judgment, and that's not an ending I'm willing to accept."
His mind raced, processing everything with his new, enhanced brain. He had been excited and overwhelmed when he first fused with Muzan's memories and power, but he quickly forced himself to calm down. As someone who had already faced death once, his will to live was absolute. He would destroy anything and anyone that threatened his new life. There would be no exceptions.
He focused, sifting through Muzan's memories. The current time is… the very beginning of the storyline.
Countless scenes from the story he knew flashed through his mind. Tanjiro Kamado is about to go to Mount Fujikasane for the Final Selection.
The story of Demon Slayer was about a kind young boy named Tanjiro, whose sister was turned into a demon. He joins the Demon Slayer Corps to find a cure for her and to defeat the Demon King, Muzan Kibutsuji.
Unfortunately for the original Muzan, Tsukihiko was now the one in charge.
If the story continued as it should, Tanjiro would pass his test and officially become a Demon Slayer. He would team up with his friends, Zenitsu Agatsuma and Inosuke Hashibira, and begin fighting against Muzan's most powerful subordinates, the Twelve Kizuki. They would go through difficult battles on Mount Natagumo, on the Mugen Train, in the Entertainment District, and at the Swordsmith Village. Eventually, it would all lead to a final, desperate battle in the Infinity Castle.
In the end, thanks to a special medicine developed by the demon rebel, Lady Tamayo, and the sacrifice of the entire Ubuyashiki family, the supposedly invincible Demon King Muzan Kibutsuji would be defeated. He would be dragged out into the sunlight and burn away into nothing. All of his Twelve Kizuki would be destroyed as well.
As for the Blue Spider Lily, the legendary flower Muzan had searched for for a thousand years to conquer the sun? It was a flower that only bloomed for a few minutes during the day. A pathetic and miserable end for a Demon King.
"The original Muzan was truly pathetic," Tsukihiko thought with a smirk. "But lucky for me, I'm not him. I'm Tsukihiko." A genuine smile finally reached his face. "That means none of that has to happen. That future doesn't exist for me."
He continued, "Since fate brought me here and gave me the power of the Demon King, giving me a second chance at life, then everything from now on will be completely different."
As he made his decision, a sharp and powerful aura exploded from his body, as fearsome as a tiger leaping down from a mountain.
"Nakime," he called out, his voice calm but filled with authority.
The moment the name left his lips, brilliant light flashed in his eyes. Almost instantly, the strange, echoing sound of a biwa playing filled the air. The space around Tsukihiko twisted and folded in on itself, the room shifting and reassembling in impossible ways.
When Tsukihiko opened his eyes again, he was in a different place. Before him knelt a woman in a dark kimono, holding a wooden biwa. Her long, black hair covered her face, leaving only a single eye visible. She was Nakime, the demon who controlled the Demon King's fortress.
"Master," she said, her head bowed.
Tsukihiko's voice rang out, cold and absolute. "Assemble the Twelve Kizuki. From now on, this world will be ruled by me."
An incredible wave of energy swept out from behind him, like a massive curtain being unfurled across the sky. Dazzling lights pulsed through every corner of the Infinity Castle, signaling the command of its master.
At that exact same moment, every demon across the land, human or otherwise, who shared Muzan Kibutsuji's blood felt a sudden, terrifying chill run down their spine. It was a feeling of absolute dread and inescapable unease.