The past few days had been both painful and exhilarating for Kakashi.
Ever since Muzan instructed Might Guy to challenge him regularly, the green-headed whirlwind had made a habit of sparring with Kakashi at every opportunity—
even ambushing him while he was using the restroom.
"Damn you, Muzan! This green watermelon-head attacked me while I was in the bathroom! It's all your fault!"
Fuming, Kakashi had long stopped calling him "brother." He wanted revenge—no, justice!
Muzan, sitting calmly with a faint smile, spoke in his usual soft but teasing tone.
"Don't be so dramatic. You've now seen what a hard-working genius looks like. Feeling the pressure yet?"
The air carried a faint scent of blood. It was clear that Kakashi hadn't come out of his last fight unscathed—Guy's relentless training was starting to pay off.
Seeing this, Muzan decided it was time to teach his brother something powerful in return.
"Listen, Kakashi. The greatest technique of the Hatake clan isn't swordsmanship… but a secret move passed down through generations. It's called—One Thousand Years of Death. Let your brother show you how it works."
Kakashi's eyes widened in awe.
"Really?! It's stronger than the Hatake Sword Style?!"
Recently, he had begun to notice Guy's growth. With every match, Guy's strength was rising at an alarming pace.
At this rate, Kakashi thought bitterly, he might actually catch up to me.
Just as Muzan was about to begin his ridiculous "lesson," a voice thundered from the doorway—deep, commanding, and full of bloodlust.
"Enough nonsense!"
The door slammed open.
Sakumo Hatake, the White Fang himself, stood there with a dark expression. His gaze swept over his two sons, equal parts frustration and disbelief.
How did I end up with two such strange children?
After years of hard work restoring the Hatake name to honor, Sakumo couldn't let them ruin it with their antics.
But when his eyes landed on Muzan, his stern tone softened.
"These next few weeks, focus on training under Nobibei. And both of you—learn to get along with your classmates. You won't make any friends behaving like this."
Sakumo sighed with the weary look of a father who'd aged too fast.
He wasn't just worried about their discipline—he worried they'd grow up so strange that neither would ever find a wife.
If that happens, the Hatake line might really end with me…
"I still don't get why I have to go to the Academy," Kakashi grumbled. "I could already apply for the genin exams."
He hated wasting time playing with toddlers. Especially that hyper girl Rin Nohara, who wouldn't stop talking to him, and that idiot Obito who followed her around like a puppy.
"It's not time yet," Sakumo replied firmly.
As an elite jōnin—an S-rank shinobi in all but title—he could feel the rising tension among the great nations.
Conflict was coming. The air smelled like war again.
"When the leaves dance, the fire's will burns brighter," Sakumo murmured.
Even if war came, men like him would be the first to march out. That was the duty of the White Fang.
He set dinner on the table. After another exhausting day, he just wanted peace at home.
But when he looked down at his meal, he frowned.
"Hey… where's the rabbit meat?"
Kakashi perked up. "Yeah! Muzan bought a rabbit from the pet shop after school. I was looking forward to dinner."
"Oh, the rabbit?" Muzan said innocently. "That's for an experiment. My Kekkei Genkai awakened recently—I need to test it."
Sakumo froze halfway through sitting down.
Muzan disappeared into the next room and returned holding a trembling white rabbit in his arms.
Even before anything happened, Sakumo could sense danger—a beastly aura radiating from his son that set every instinct on edge.
A kekkei genkai…? The Hatake clan has no recorded Kekkei Genkai.
He was still young enough to have more children, he mused wryly. Maybe our bloodline's changing after all.
—
The rabbit squirmed desperately, sensing the threat. But Muzan's expression remained calm.
Suddenly, a mouth opened in the center of his palm—its jagged teeth glistening as it bit down into the rabbit's body.
Kakashi jumped back in horror.
"What the hell is that?!"
Sakumo didn't flinch.
"Don't overreact, Kakashi. Kekkei Genkai come in many forms. Some alter the body entirely."
He spoke with the calm of a veteran who had seen the world's extremes—from the Kaguya clan's Shikotsumyaku, to monsters that had long since ceased being human.
But Muzan wasn't devouring the rabbit.
Instead, his palm-mouth injected his own blood into the animal.
Moments later, the rabbit's body began to convulse.
Its muscles swelled, bones cracked, and fur bristled—growing to the size of a wild boar within seconds.
Its once-docile eyes turned crimson, burning with feral rage.
Sakumo instantly drew his blade, stepping in front of his sons.
The creature was no longer a rabbit—it was a beast, stripped of reason, its mind overwhelmed by the monstrous energy inside it.
"When turning a creature into a demon, there's always a brief madness," Muzan said coolly, watching his creation thrash.
"Don't worry—it won't last long."
Right on cue, the creature let out a strangled scream before bursting into a spray of blood.
Nothing remained but a crimson stain on the tatami.
"Failed."
The room was a wreck—splattered with blood, overturned dishes, and scorch marks.
Yet Sakumo's face showed no fear, only solemn understanding.
The power was immense.
For an ordinary rabbit to endure even a few seconds was impressive. But this Kekkei Genkai… its nature was dangerous. It didn't strengthen Muzan directly, but rather allowed him to enhance others—or corrupt them.
Still, Sakumo worried his son would be disheartened.
He reached out to ruffle Muzan's hair—a rare gesture of affection—but the boy subtly dodged. Sakumo sighed, mistaking it for sulking.
"Don't lose heart. Failure means nothing to a ninja. True strength is built from discipline, not luck. Train well in the Hatake Sword Style—you'll achieve great things someday."
"You misunderstand, Father," Muzan replied quietly, eyes glinting red beneath his fringe.
"I'm not disappointed."
He wasn't angry about the experiment. He simply didn't like being treated like a child.
And as for failure? That was hardly the case. The rabbit hadn't died because the technique was weak—it had died because the power was too great.
He could now create beings like demons—controlled entirely by his will.
The Twelve Demon Moons had once been nearly immortal monsters; this bloodline had the same potential. It was terrifying—and exhilarating.
Even so, Muzan calmed himself quickly. He noticed the mess around them, then feigned dizziness. His face paled.
"Father, I think… there might be side effects from using the Kekkei Genkai. I'm not feeling well. I'll go rest now."
Before Sakumo could respond, Muzan grabbed Kakashi by the arm and bolted for the door.
"Hey! Get back here and clean up the room!" Sakumo shouted.
He sighed, exasperated, but couldn't hide the proud smile tugging at his lips.
So, even Muzan has found his power. It's time I teach him the Hatake Sword Art properly.
---
Outside, under the silver moonlight, Kakashi walked silently beside his brother. His expression was complicated.
They both shared the same silver-white hair, the same clan, yet tonight Kakashi felt like he was seeing Muzan for the first time.
"What's wrong, Kakashi?"
"Brother," he said after a long pause, "I want to spar with you."
Over the past few weeks, Kakashi had noticed something unsettling—Muzan's body was changing.
His chakra control, his endurance, even the way he breathed—it all felt… unnatural.
At school, Muzan could maintain a steady flow of chakra for hours without pause.
How much stamina does he have? What even is he?
For the first time, Kakashi wondered if the brother he'd always thought of as frail… might actually be the strongest one between them.