"So this is Lord Sakumo's child? Poor thing."
"They say he's had a severe skin disease since birth — he can't be exposed to sunlight."
"His body's terribly weak. I even heard he was nearly stillborn."
The Land of Fire.
Within the Hatake household of Konohagakure, a young boy sat quietly under the shade, dressed entirely in black to block the light of the sun. Around him, villagers whispered among themselves, their pitying voices cutting into his ears.
"Delicate," "sickly," "too fragile to live"—labels that had followed Hatake Muzan ever since he transmigrated into this world of shinobi.
To many, he was nothing short of a disgrace to the Hatake name.
After all, his father was the legendary White Fang of Konoha, Sakumo Hatake—
and even his younger brother, Kakashi, was hailed as a genius.
"How ridiculous."
Beneath the boy's hood gleamed a pair of crimson eyes — so vivid, so mesmerizing, that anyone who looked into them would find it hard to look away.
Just then, a small figure stepped between Muzan and the gossiping adults. A silver-haired child, barely taller than the weapon he held, pointed his kunai at them and snapped:
"Bastards! You're not allowed to talk about my brother!"
It was Kakashi.
Whenever someone insulted Muzan, Kakashi would defend him without hesitation, ready to fight anyone who dared mock his brother.
Their father's words echoed in his mind:
Your brother was born frail. Protect him.
Kakashi turned to Muzan and sighed.
"I knew you'd be hiding here again, sitting quietly. Father said you should be reviewing your lessons. Tomorrow's the Ninja Academy entrance exam — we're signing up together! And don't even think about asking me to help you cheat."
For as long as he could remember, Kakashi had been worrying about his brother. Muzan wasn't just physically weak — he was incredibly lazy, showing no interest in anything that didn't directly concern him.
Even Sakumo himself had given up on pushing him to train in the Hatake Sword Style, deciding it might be better for Muzan to live a peaceful, ordinary life in the village instead.
But today, something was different.
Still seated on the wooden threshold, Muzan slowly raised his head. Then, standing up, an overwhelming pressure radiated from him — a commanding, almost otherworldly aura that seemed far too powerful for a boy his age.
"Don't worry," he said coldly. "There are no weaklings in the Hatake clan. When I enter the Academy tomorrow, I won't disappoint you."
Kakashi blinked in surprise. That presence—just for a moment, it felt dangerous.
He shook his head. Must be some side effect from overtraining, he thought.
"Idiot! This isn't about disappointing me — you have to actually pass the exam!"
"Clack!"
Before Kakashi could scold him further, the door behind them slid open.
Sakumo Hatake appeared, his expression weary.
"You two again? The Academy entrance exam is tomorrow, and you're still arguing? Go finish your review already. Dinner's ready — eat before it gets cold."
With one hand, he grabbed Kakashi by the collar and lifted him effortlessly.
"And Kakashi," Sakumo sighed, eyeing his son's perpetual dead-fish stare, "we really need to fix that attitude of yours. Keep looking like that and you'll never find a wife."
Meanwhile, Muzan remained in the shadows, silent. When he finally turned around, his crimson eyes flickered.
Something in him… had changed.
---
Later, while tidying the house, Sakumo felt a faint disturbance — the presence of something bestial, wild. His instincts as an elite shinobi flared. Concerned for his sons, he immediately went to check, circling the yard.
No sign of any intruder. Only Muzan, standing quietly in the darkness.
Never underestimate the senses of a Kage-level shinobi — especially one renowned for his mastery of taijutsu.
"What happened just now?" Sakumo asked calmly.
"I don't really know," Muzan replied.
He described the earlier scene to his father, intentionally exaggerating the villagers' cruel remarks.
"Then I got angry… and suddenly, something inside me awakened. A strange power."
A flawless explanation — who would ever suspect a child of lying?
Sakumo froze, deep in thought. It wasn't impossible. After all, powerful emotions could awaken kekkei genkai — like the Uchiha and their Sharingan. Could it be that the Hatake clan… also possessed a hidden bloodline?
"If that's the case, then it's a blessing," Sakumo finally said with a gentle smile. "Don't tell anyone for now. Focus on your training, Muzan. Become a true shinobi — a strong one."
For Sakumo, Muzan had always been a source of worry — not because of his lack of potential, but because of his fragile body.
Even the sunlight could kill him. Reaching adulthood at all seemed uncertain.
He had consulted Tsunade, Konoha's greatest medical expert, but even she found no cure. In the end, she theorized that Muzan's condition might stem from a genetic defect — a flaw within his very bloodline.
To conceal his true nature, Muzan lied, claiming to suffer from chronic anemia. Every few weeks, Sakumo would take him to the hospital for a blood transfusion.
In reality, Muzan required fresh blood — human or animal — to survive.
To hide this, he pretended to eat normal food during meals, though sustenance meant little to him now. His body was evolving — perfecting itself. Even without eating for days, he remained as strong as ever.
---
That evening, as the three of them sat around the table, Sakumo finally set down his chopsticks and spoke.
"Muzan, you may be starting late, but under my guidance, you'll catch up quickly. Study hard at the Academy. You'll do well."
He paused, glancing at Kakashi.
"And you — your talent is remarkable. If you keep training and master all five chakra natures, whether in the Hatake Sword Style or ninjutsu, you could even surpass me one day."
Both boys fell silent, listening.
"Tomorrow's entrance exam will be easy," Sakumo continued. "Just some physical assessments and a few questions about the Will of Fire."
He wasn't worried — both his sons were exceptional in their own ways. Still, when his gaze landed on Muzan, his tone softened.
"Whatever happens, never expose yourself to sunlight."
That was his greatest fear. The Academy wasn't home — it wouldn't be as safe.
"Kakashi, take care of your brother at school," he added seriously. "His health is still fragile."
For once, Kakashi didn't argue. His brother's safety was the one thing he truly cared about.
He still remembered the day he'd seen Muzan's exposed skin begin to smoke under the sun.
"Don't worry, Father," Kakashi said firmly. "I'll protect him."
Sakumo smiled faintly. "That's the bond of family."
But deep down, he couldn't have known —
Muzan no longer needed protection.
As time passed, his power would only continue to grow.
And as for the sunlight and the blood he required… he already had plans.
When the time came, his path as a shinobi would lean toward one particular field—
medical ninjutsu.
Because even monsters needed a way to heal.