The sun had already climbed high, and Yosuke remained crouched in the dark corner of his room, hiding from its rays.
Suddenly, shouts echoed from outside:
"Murder! Murder!"
Startled, Yosuke avoided the patches of sunlight and called toward the door:
"Is anyone there? Someone, come in!"
His attendant maid opened the door and stepped inside.
"What's happening outside?" Yosuke asked.
The maid answered gravely:
"Master Muzan… Master Muzan killed the physician!"
Her words hit Yosuke like a bucket of ice water. Summoned by the steward, she quickly shut the door behind her and left.
Yosuke sat in stunned silence, his gaze empty.
What the hell? This fast? I was planning to get used to my new powers and then sneak into Boss Scum's room to finish him off. But now he's a demon already. How am I supposed to kill him? Drag him into the sunlight for a family barbecue and die together?
Freshly bonded with his system, Yosuke had no desire to die a martyr just yet. He needed to think long-term.
"System, you there? Hey, are you there? This is urgent!"
The reply came at once:
'Say what you want. Don't ask pointless questions.'
…His system actually had an attitude.
Cautiously, Yosuke asked:
"Other than the starter skill you gave me, is there any way to grow stronger?"
'Yes. The fastest method—consume humans.'
"…Not happening. Give me another option!"
'Slaying demons works. Training, too. When the system detects your strength has reached the threshold, you'll earn chances at random draws.'
Yosuke felt a headache coming on.
In this world, the only demons are me and that resentful bastard Muzan. And I can't exactly kill him… Forget it, I'll just train.
So he obediently stayed inside the clan estate, wielding a katana and forcing his frail body through drills.
"Swordsmanship proficiency +1, +1…"
Though Muzan had killed, as the son of the Ubuyashiki family head the incident was covered up. Even so, a heavy shadow now loomed over the household.
Day by day, rumors spread:
"The Ubuyashiki head's two children never leave the dark rooms they hide in. Worse still, word is that the eldest, Ubuyashiki Muzan, has begun secretly consuming human flesh and blood…"
Fear swept through the clan. No servant dared attend Muzan. Those who did—within seven days, without exception—vanished.
The joy Takuto and Mikako once felt when their children showed signs of recovery had long since turned to gloom.
Because of Muzan, Takuto was stripped of his position as clan head, sinking into depression.
Mikako's grief festered, leaving her bedridden.
When night fell, Yosuke slipped from his room and went to his mother's chamber.
Seeing her haggard face tore at his heart. The woman who had loved him so dearly was now reduced to this.
Burying his head in her arms, he whispered:
"Mother…"
Mikako opened her eyes, saw her child, and tenderly stroked his cheek.
"Yosuke… you came."
But then she froze.
Before her was Yosuke, but his eyes glowed red with pain, his skin pale as death, and two sharp fangs jutted from his mouth.
A sorrowful realization struck her:
I should have known. Both brothers took the same medicine… Yosuke, tell me—have you eaten humans too?
Yosuke quickly shook his head.
"No, Mother. My body has changed, but I don't crave human flesh."
Mikako smiled faintly, ruffling his hair.
"That's good… That's good. Yosuke, your brother has changed completely. Never become like him. He can no longer be called human."
Now, the Ubuyashiki clan's separate residence had become a forbidden ground. No one dared enter.
The rest of the clan whispered of killing Muzan—but none who entered that place ever returned.
Yosuke dared not go either. Though he was now a demon, apart from his regeneration he had little to rely on. Venturing there would mean death.
Leaving his mother's room, he returned to his own—only to break into a cold sweat.
For there, seated casually in a chair, was Ubuyashiki Muzan. In his hand, he gnawed on a severed human arm as if it were a chicken wing. The sight made Yosuke's blood run cold.
"So… you became a demon too." Muzan's icy voice cut through the air.
Yosuke froze, unable to move. In the blink of an eye, the hand in Muzan's mouth had been stripped bare, reduced to spotless white bone.
Damn it! Even when I eat chicken, I don't clean the bone that well!
First strike is best!
"Blood Demon Art—Shadow Wolf!"
Yosuke's shadow surged forth, forming a wolf that lunged at Muzan with a feral roar.
But hope turned to despair in an instant.
From Muzan's back sprouted a barbed whip. With a single strike, it shredded Yosuke's Blood Demon Art into nothing.
A cold wind stirred, and Muzan appeared at Yosuke's side in a blur. With disdain, he seized Yosuke's arm—twisting and pulling until it tore clean from his body.
Yosuke screamed in agony. His limb regenerated instantly, but the pain did not vanish. The searing torment sent him collapsing to the floor.
"So weak, Yosuke. You haven't eaten humans, have you? Even as a demon, you still cling to pity for them? Laughable. Humans are nothing but food to us."
Muzan raised Yosuke's severed arm to his mouth, bit into it, then spat it out in disgust.
"Disgusting. I thought that, as a fellow demon, you might taste better. But no—you're worthless. As my brother, you're not even fit to be eaten."
Yosuke had prepared himself for Muzan's overwhelming strength, but the gap was greater than he'd feared.
Placing a gentleman's hat on his head, Muzan strode toward the door. He swept his gaze across the Ubuyashiki estate and declared:
"From this day forward, I am no longer Ubuyashiki Muzan. I am Kibutsuji Muzan!"
With that proclamation, he vanished into the night.
Muzan was gone from the Ubuyashiki clan. No one knew where he went.
But soon, nearby towns whispered of demons devouring humans. And inevitably, the blame turned toward the Ubuyashiki family.
Slandered and reviled, the clan became the target of public outrage. Unable to endure the shame, Takuto took his own life in atonement.
Upon hearing the news, Mikako's illness worsened once more.
But even that was not enough. For Yosuke still lived—and the clan, united in fear and rage, resolved to drag him into the sunlight, to burn him alive.