Hatake Kakashi was not the kind of child who failed to understand the world.
In truth, he thought far more deeply than most adults expected of someone his age.
In this chaotic era, he had already seen blood — had already taken lives on missions, even if the victims were only mountain bandits.
When he returned home yesterday, he spent the entire night in silence, thinking.
He understood what Aizen Sōsuke's "protection" truly meant.
But in Konoha, the relationship between an adopted father and a disciple was never simple.
There had been similar cases before — "adopted sons" who were in truth disciples. Konoha's education system might have claimed to nurture all shinobi equally, but in reality, each clan's secret arts and techniques were passed down privately from childhood.
Every master–disciple relationship in Konoha was a living textbook of hidden arts — techniques that could never be written down, only passed on through experience and intuition.
Thus, beyond the Academy's basic curriculum, many orphans were adopted by older shinobi to inherit techniques, preserving the village's secret arts in another form.
But Aizen Sōsuke…
He wasn't a powerful shinobi. He possessed no famous secret arts. He was young, too — barely an adult.
What business did he have calling himself a foster father?
An older brother or an uncle, maybe — but a father? That was going too far.
—
"Are you doubting my strength, Kakashi-kun?"
Aizen's gentle voice broke through the boy's thoughts. He smiled faintly, the ever-calm warmth on his face unwavering.
"There's a decisive difference between a genin and a chūnin," he continued softly.
"You may test me if you wish. After all, I know you still harbor suspicion toward me because of your father, Sakumo-kun. But shouldn't a father and son speak frankly, face to face?"
Kakashi's eyes narrowed.
"…I understand."
In one fluid motion, he drew a kunai and lunged forward — straight for Aizen's neck.
Even an ordinary jōnin would've been hard-pressed to react to an attack that fast.
At the last second, Kakashi shifted the trajectory. The shoulder will do, he thought. He's done nothing wrong — not yet.
But instead of the familiar resistance of flesh, there was a sharp metallic clang.
Clink!
Kakashi's eyes widened.
Aizen sat calmly, one hand raised — two fingers effortlessly pinching the edge of the kunai.
"That's the reality, Kakashi-kun."
The man's tone was soft, but his expression serene — almost kind.
From his fingertips, faint blue light pulsed rhythmically, spreading across his skin in delicate geometric lines, synchronized with his heartbeat. It looked almost like liquid chakra, solidified into a translucent crystalline sheen.
"As my son," Aizen said, "this is my first gift to you."
He hooked his finger lightly, disarming the kunai with a flick, then adjusted his glasses with the other hand, smiling as though this were a simple demonstration rather than a display of power.
"It's a defensive technique — a secret method. I never wanted children like you to set foot on the battlefield. That was the First Hokage's wish as well. But in this world, without power, you're nothing but prey."
"I've seen the battlefield only briefly, but it was enough. Watching people kill each other… it made me feel sorrow, not pride. I lack the medical prowess of a healer, and my chakra control isn't delicate. But human beings… are creatures who think."
Aizen held up his hand, the blue aura still shimmering faintly.
"By injecting or coating the skin with chakra-reactive fluid, then circulating chakra through the body, one can form a thin yet powerful defensive membrane. When combined with sealing patterns etched under the epidermis, this technique manifests automatically. The result… is what you see now."
He smiled faintly.
"I call it—Seijūzō, the Still Blood Armor."
Kakashi's kunai pressed against Aizen's skin again, but couldn't even scratch him. The sound was like steel scraping steel.
Aizen — a mere "chūnin" — sat cross-legged in the center of the calligraphy chamber, his calm gaze fixed on the boy before him, while Kakashi strained with all his might. The shimmering blue light along Aizen's fingers was as unyielding as a mountain.
"The technique manipulates blood and chakra flow," Aizen explained calmly. "It can resist ordinary slashes, even elemental jutsu from most genin and mid-level chūnin."
He looked at Kakashi — the boy's one visible eye wide with disbelief, his arms trembling from exertion.
"You can't even sever a strand of my hair, Kakashi-kun."
Then, almost kindly:
"Take this as a lesson. Never play by your enemy's rules. Otherwise, you'll learn the taste of regret."
He straightened the collar of his haori and continued evenly.
"Seijūzō requires strict conditions and specialized tools. That's why I wear a haori instead of a flak jacket — authorized by the Third Hokage himself. You see, privileges aren't gifts. When someone has what others lack, don't be envious — ask why. Envy clouds judgment."
"Tch!"
Kakashi clicked his tongue. Just a chūnin, he thought bitterly, a dropout, Father said…
Before Aizen could say another word, the boy's small figure blurred — replaced by a puff of smoke and a hanging scroll of calligraphy reading 'Never Give Up.'
A Substitution Jutsu.
"Hmm… a substitution, is it?" Aizen murmured, his voice smooth and magnetic.
"Excellent instinct. When a frontal assault fails, a flanking strike is logical. But—"
The sound of steel striking cloth cut him off.
"It's useless."
Kakashi's kunai struck from behind, tearing Aizen's haori slightly — but doing no harm at all. The weapon simply skidded off as if it had hit tempered steel.
The boy's eyes widened. What kind of jutsu is this…?
"Now you see, Kakashi-kun," Aizen said softly, turning his head just enough for the blue glow to reflect off his lenses. "This is the first gift I offer you — a non-ranked, self-sustaining defensive technique: Seijūzō."
From his hair to his toes, his entire body shimmered faintly, sheathed in azure light. The kunai embedded in his back clattered to the floor with a dull thud.
Aizen remained seated in perfect composure, turning to glance up at the boy now crouched on the ceiling beam, uncertain and shaken.
"This technique was meant as a life-saving art for all Konoha genin. Unfortunately, its activation disrupts chakra flow too heavily for ninjutsu. It's best suited for swordsmanship or close combat."
"I told you before, Kakashi-kun — I care about you. You're the son of the White Fang. I won't judge your father's choice, but I want you to accept this gift."
"For the sake of the Will of Fire, I'll personally pass this secret technique to you."
He smiled faintly.
"Besides… letting my late comrade's child wander this cruel world alone doesn't sit right with me. Think about it, Kakashi-kun. I'll respect your decision. Even if you refuse to be my son… take the scroll."
---
Aizen's presence was like moonlight — cold, yet elegant and strangely comforting.
From the sleeve of his haori, he drew a small scroll and placed it on the writing table before him.
Kakashi hesitated. The man's tone, his gestures — all of it was genuine. If a person's actions and sincerity were both real, should he still treat them as an enemy simply because of his father's warning?
Aizen's smile was warm and kind.
The scroll lay there, unguarded — offered freely.
Kakashi's will wavered.
He was only six.
Aside from his father, no one had ever truly spoken to him with such respect, such understanding.
And now that his father was gone… this man was all that remained.
—
Just then, the silence was broken by a shadow at the doorway. A black-clad figure knelt on one knee — an ANBU.
"Aizen-chunin. Lord Third requests your presence at the council meeting."
"Ah. Of course."
Aizen smiled politely, setting aside his brush and the hanging scroll of 'Never Give Up'. He rose gracefully and looked back toward Kakashi on the beam.
"Think it over carefully, Kakashi-kun. I have great hopes for you. Don't disappoint me."
"My own ability is limited — Seijūzō's development has reached its peak. I've theorized a reverse form, Active Blood Armor, but it remains untested. Perhaps you'll perfect it one day."
"Now, if you'll excuse me."
---
As Aizen stepped out, his white haori swayed gently behind him. The ANBU disappeared with him into the corridor's shadow.
Kakashi stared down at the desk, at the scroll still lying there. His emotions twisted into something he couldn't name.
Aizen Sōsuke… is he really just an ordinary chūnin?
He recalled how effortlessly the man had caught his kunai — with one hand.
He recalled the glowing script 'Sky' inked on the desk.
And now, the Hokage himself was summoning him to a private meeting.
Could the Third Hokage be mistaken? Could the ANBU, the clans, the entire village be deceived?
No — everyone trusted him. Even the Uchiha treated Aizen with courtesy.
Almost everyone said the same thing:
He was a good man — Konoha's kindest shinobi.
Only his father had said otherwise.
And his father… had taken his own life.
Kakashi's chest tightened. A forbidden thought surfaced in his young mind — one that felt like betrayal.
Maybe… maybe Father was wrong?
And so, the boy stood atop the beam, trembling — lost in the deepest confusion of his young life.