Chiyoda Ward, Tokyo.
As the absolute core of politics and power in all of Japan, the streets here remained spotless, even in the dead of night.
Western-style buildings stood alongside high-spec traditional Japanese estates. Those living here were without exception from the wealthy and noble upper class.
Inside a three-story luxury Western villa, the mahogany study on the second floor was lit by a warm yellow gas lamp. A soothing cello piece was playing on the gramophone.
In the center of the room, which was covered in expensive rugs, a young boy about ten years old sat quietly in a high-backed leather chair. He possessed a sickly pallor as he flipped through a thick German medical text.
"Toshikuni-sama, it is time for your medicine." A servant dressed in a maid's uniform entered cautiously, carrying a silver tray.
On the tray were several pills and a glass of warm water.
"Leave it on the table and get out. Do not let anyone disturb my reading." The boy didn't even look up. His voice was youthful, yet it carried an air of undeniable coldness.
"Yes."
The maid dared not say more. She set down the tray, bowed respectfully, and retreated, gently closing the door behind her.
As the door closed, only the music from the gramophone remained in the study.
The boy closed the book in his hands. His originally black eyes shifted quietly under the light, transforming into red vertical slits.
Kibutsuji Muzan.
In his search for the "blue spider lily" that could overcome sunlight, he constantly changed his identity to lurk within various strata of human society.
Currently, he was the frail and sickly adopted son of this wealthy merchant family in Chiyoda Ward.
Suddenly, the temperature in the study dropped without warning, and even the flame of the gas lamp began to flicker violently.
In the shadows before the window, a figure kneeling on one knee gradually emerged.
Short pink hair, a body covered in deep blue tattoos, and clothes in tatters. The muscles in his right arm were twitching slightly, as if they had just undergone some high-intensity reconstruction.
It was Akaza, who had sprinted all the way back from the scene of the Mugen Train.
"Muzan-sama." Akaza bowed his head deeply, his voice carrying an irrepressible sense of self-reproach and humiliation.
Muzan turned the chair and looked coldly at this subordinate whom he valued quite highly.
In his impression, Akaza was a pure martial arts fanatic who could easily slaughter a Hashira upon encounter. He rarely ended up in such a pathetic state.
"I sent you to find the blue spider lily and handle the meddlesome Demon Slayers along the way. Is this ridiculous appearance of yours telling me that you failed?" Muzan's voice wasn't loud, but every word seemed to carry an invisible, heavy pressure.
"This subordinate is incompetent."
Akaza clenched his teeth as the images of that "fierce battle" from a few hours ago surfaced in his mind. He squeezed his fists tight.
"I encountered the Flame Hashira, a boy wearing hanafuda earrings, and a bizarre swordsman using lightning techniques. They joined forces to stall me until the sun rose. To preserve my life, I could only retreat."
"Stalled until dawn by three swordsmen?"
A flash of violence crossed Muzan's eyes. He didn't care about the process, only the results.
For an Upper Rank to fail to kill a few Demon Slayers was an unforgivable dereliction of duty in his eyes.
However, being suspicious by nature, his gaze swept over Akaza and noticed the turbulence in his aura.
Without any extra words, Muzan raised his right hand and lightly tapped his index finger toward Akaza's forehead from across the room.
The suppression of their blood connection activated instantly.
As the progenitor of all demons, Muzan could easily read the memories and experiences of any demon.
A bridge of consciousness was instantly established, and the "battle recording" of Akaza's experience by the Mugen Train began to play rapidly in Muzan's mind like a slideshow.
In the images, on the wilderness where the train had derailed:
That Flame Hashira named Rengoku Kyojuro, when facing Akaza's killing moves, suddenly manifested flame-like marks on his forehead and cheeks.
With the appearance of the marks, his speed and strength increased significantly, and he clashed head-on with Akaza while brandishing flames.
On the flank, the youth wearing hanafuda earrings was gritting his teeth, using a sword technique as hot as the sun to interfere.
Finally, there was a black-haired young man wearing a black haori and holding a black sword. He didn't use a traditional Breathing Style. Instead, he coated his blade and body surface with lightning. He was extremely fast, moving around the edge of the battlefield like an inescapable shadow, using various tricky lightning thrusts to disrupt Akaza's attack rhythm.
The battle in the images was extremely brutal.
The Flame Hashira was coughing up blood, his body covered in wounds.
The youth with hanafuda earrings had collapsed from exhaustion.
The black-haired man using lightning was also panting heavily, his left arm hanging limply, clearly severely injured.
Just as it looked like Akaza was about to use his final Destructive Death strike to crush them all—
On the distant horizon, the first ray of sunlight pierced the darkness.
The images stopped abruptly.
Muzan cut off the memory reading and withdrew his finger. Leaning back against the leather chair, his red eyes flickered with an uncertain light.
'Demon Slayer Marks...'
Muzan's heart throbbed uncontrollably for a moment.
Hundreds of years ago, the man who had driven him into a corner and hacked him into over 1,800 fragments—Tsugikuni Yoriichi—had similar marks on his face.
Those were the cursed marks obtained by pushing Breathing Styles to their limit and burning one's life in exchange for power.
The moment he saw the Flame Hashira activate the mark, Muzan's instinct did indeed produce a sliver of fear. But immediately following that, this fear was replaced by a cold sneer.
'I see. Even after activating the mark, he could only barely withstand Akaza's attacks and was even beaten to the brink of death?' Muzan evaluated coldly in his heart.