"Tomorrow is my child's seventh day celebration. I hope you can come if you have time," Fugaku said, his tone calm, yet unable to hide the faint pride beneath it as he looked at Kagami.
Uchiha Kagami accepted the invitation, then lifted his gaze slightly, his expression composed. "Have you chosen a name?" he asked, his voice steady, his eyes resting on Fugaku with quiet curiosity.
"Itachi. Uchiha Itachi. A boy," Fugaku replied, a rare smile forming on his face, the kind only a new father would show.
Fortunately, Sasuke would inherit his mother's beauty. Otherwise, like Itachi, he might look far older than his age.
"Alright. I'll come," Kagami said simply, offering no more than that as his agreement.
As he watched Fugaku leave, Kagami's gaze darkened, the faint light in his eyes sinking into something deeper. The birth of Itachi marked the beginning of the countdown toward the destruction of the Uchiha clan.
More than ten years. That was enough. Lying on his bed, having already slept enough during the day, Kagami closed his eyes, his consciousness sinking quietly into his inner mental space.
"Kid, that old man you met in Konoha, what level is he?" Sukuna's voice echoed, low and curious, rippling through the empty space.
In the past two years, the strongest person Kagami had encountered was undoubtedly Hiruzen. A man of that level was incredibly rare. It was a pity his vitality was already declining. Sukuna had truly wanted to test him.
As for Sakumo, his strength might not match that old man's. But even in his weakened state, the sharpness of his blade still drew Sukuna's attention.
Sukuna admired strength, especially those with unwavering conviction.
Kagami considered the question carefully, his thoughts moving slowly, deliberately. In terms of raw physical ability, Sakumo was likely slightly stronger than the current Sannin, but still below the Third Hokage and others of that tier.
More importantly, there was the Nine Tails, an unpredictable existence.
A fully formed Nine Tails far surpassed the combined strength of most shinobi. Only sealing techniques could truly counter it.
To keep Sukuna from growing too arrogant, Kagami deliberately included both past and future powerhouses of Konoha in his assessment.
After all, Sukuna had asked about Konoha as a whole.
"Top twenty, maybe," Kagami replied calmly, his tone indifferent as if speaking of something trivial. "The old man I met, he is the village leader. But there are still many stronger than him."
"Interesting…" Sukuna murmured, his voice lowering, his grin spreading wide. Amid a sea of blood and corpses, he smiled like a demon. "You brat, lend me your body and let me have some fun," Sukuna said, his tone playful, yet laced with something far more dangerous. "Give me just five minutes of control each day, and I will teach you how to use my power."
Kagami said nothing. Instead, he reached into the gap within the seal, pulling out a mass of black energy. It writhed faintly in his hand as he kneaded it, then swallowed it without hesitation. He glanced at Sukuna with open disdain. "Do I need you to teach me?" Kagami said, his voice calm, almost mocking. "If I keep consuming this for another two years, I might even strip you bare."
"…How are you even stealing it?" Sukuna snapped, genuine confusion breaking through his usual arrogance. He could not feel his power decreasing at all. Even within this mental space, his cursed energy continued to grow.
In just a few years, he had accumulated more power than the entire sorcerer world had gathered over his life.
He was stronger than he had ever been, yet he still could not break this strange seal. Not even his world cutting slashes could damage it.
After swallowing the energy, Kagami felt a subtle shift within himself. Once he fully digested it, using that's power would become far easier. With enough repetition, it might even become a standard ability.
He activated his Sharingan, the three tomoe spinning slowly as he began his training.
Over the past two years, thanks to medicinal baths, his physical growth had reached the level of a thirteen or fourteen year old Uchiha.
The Uchiha naturally possessed more chakra than ordinary shinobi due to their immense spiritual energy. But the upper limit of chakra was determined by physical energy.
Some members of the Senju and Uzumaki clans possessed chakra comparable to that of the tailed beasts.
Compared to them, the Uchiha had always been considered lacking in raw reserves. Even Madara needed to capture the Nine Tails to sustain prolonged combat against Hashirama.
Thinking of this, Kagami glanced at Sukuna again, a faint trace of disdain lingering in his eyes.
Tailed beasts were created by the Sage of Six Paths through Yin Yang Release. Each one was essentially a living power source, though with different limits. But Sukuna was purely Yin. And because Kagami's spiritual energy far exceeded his physical energy, his Yin Release chakra was more than sufficient.
"Hey, brat, what kind of look is that?" Sukuna said sharply, his voice rising with irritation as he noticed Kagami's expression.
Kagami sneered faintly. "Your power is not that impressive either," he said calmly, his eyes cold. "I am thinking of catching you a neighbor."
"You bastard, what do you mean by that?" Sukuna snapped, anger flashing through his voice.
Kagami ignored him. With a thought, he isolated Sukuna's voice, cutting off the noise completely.
Silence returned.
He raised his hand. A bright blue sphere of chakra formed in his palm, spinning steadily. Kagami focused, his eye sharpening slightly as he attempted to introduce fire nature into the sphere.
The moment a flicker of flame touched it.
Boom.
A violent explosion erupted, scattering the chakra instantly.
As expected, it failed. Kagami remained expressionless. He was not like Naruto, who could rely on shadow clones to accelerate training.
He could only repeat the process again and again. Relentlessly.
If wind release could turn Rasengan into Rasenshuriken. Then what would fire release create.
*******************
At just seven and a half years old, Uchiha Kagami already stood around one and a half meters tall. For the celebration, he wore a loose dark blue robe that draped lightly over his frame, its folds shifting softly as he walked.
His features were sharp, almost too refined for his age, and a faint smile lingered at the corner of his lips, as if nothing in this world could truly disturb him.
Behind him, a two and a half year old child followed closely, his small steps uneven, his wide eyes filled with curiosity as he looked around at the bustling gathering. "Big brother, there are so many people here. What's happening?" the child asked, his voice soft, tugging lightly at Kagami's sleeve as he looked up.
"A celebration for the birth of a child," Kagami replied calmly, his tone indifferent as his gaze drifted forward, settling briefly on the baby cradled in another's arms.
"Kagami, you've come," an older man said as he approached, his voice carrying a hint of familiarity. Uchiha Bokuto stopped beside him, his eyes shifting toward Fugaku and his family in the distance, then narrowing slightly as a sneer formed on his lips.
"I heard someone already calling that child the young clan leader," Bokuto said, his tone dripping with disdain. "Heh, We Uchiha are not like the Hyuga. We do not cling to main family games," he continued, folding his arms as his gaze sharpened. "Even Fugaku was only called that after proving his talent. A baby wrapped in cloth. Does he deserve it?"
"If he grows up normally, then perhaps he will," Kagami answered calmly, his expression unchanged, his voice neither agreeing nor denying.
He did not like Itachi. But that did not diminish the boy's talent.
"I often feel like your eyes can see the future," Bokuto said with a sigh, though a faint smile appeared as he patted Kagami's shoulder. "In a few years, you might even defeat Fugaku. When that time comes, I will start an internal war in the clan," he added, his voice lowering slightly, filled with intent. "You are the one fit to lead the Uchiha."
Kagami shook his head lightly. In one or two years, the Third Great Ninja War would begin. The borders were already growing unstable, small clashes becoming more frequent with each passing month.
According to how events would unfold, the Uchiha would not even step onto the battlefield of the Hidden Mist until the later stages of the war.
And more importantly, the clan itself was not unified.
The radicals were the majority, yes.
But many still chose to side with the village. Just like Obito, who would later join Minato's team. He was only one example among many. Where had he obtained his Sharingan before the massacre. And Kakashi being allowed to keep a Sharingan was itself a compromise the Uchiha made with the Fourth Hokage.
For a thousand years, the Uchiha had upheld one absolute rule.
No outsider could ever possess the Sharingan. If they did, the entire clan would hunt them down without exception.
Without Madara, the Uchiha were no longer the dominant force they once were. They had become something that could be suppressed. Fugaku had likely not yet awakened the Mangekyo Sharingan. He would only reach that point during the Third Great Ninja War. If it was only three tomoe.
"I will challenge Uchiha Fugaku soon," Kagami said calmly, his voice quiet, yet firm.
Bokuto's pupils shrank slightly, his expression stiffening. "So suddenly?" he asked, his tone sharpening with surprise.
"It is nothing serious," Kagami replied, glancing around at the gathered clan members, his gaze steady. "Since everyone is here, we may as well do it now," he continued, his tone unchanged. "but I have no intention of becoming clan head just yet."
Fugaku lacked decisiveness, and the natural talent to lead. But he could still serve as a transitional figure.
Kagami planned to take that position at the beginning of the Third Great Ninja War, when the Third Hokage's faction would have less room to act against him.
**************
The seven day celebration had gathered nearly all Uchiha eligible to attend clan meetings, along with many ordinary members.
Fugaku raised his cup slightly, his gaze turning toward Bokuto's direction. "Elder Bokuto, thank you for your contributions to the clan," he said calmly, his tone respectful, though measured.
"Kagami, Shisui, Itachi is your younger brother," Fugaku continued, his eyes briefly resting on them, his expression softening just slightly. "Please take care of him in the future."
The clan members exchanged glances. The division within the Uchiha was already clear. At present, the village maintained a peaceful stance, and Fugaku leaned toward coexistence. Most Uchiha within the Police Force shared that same inclination.
Only later, when the village pushed too far, would the radicals rise and overpower them.
At the founding of the village, the Uchiha had grown tired of endless war.They had even turned against Madara.
Kagami set his drink down slowly, then rose to his feet. "Clan Head, on this day of blessing, I would like to request your guidance in ninjutsu," Kagami said, his tone polite, yet steady, his eyes resting directly on Fugaku.
Fugaku's smile did not change. "Of course. I will wait for you at the training grounds tomorrow," he replied calmly.
Kagami's lips curved faintly. "Do I need to be clearer?" he asked, tilting his head slightly, his gaze sharpening. "I am challenging you, Uchiha Fugaku."
The hall fell into a brief silence. If it were an ordinary child, no one would take such words seriously. Just like a child declaring he would become Hokage, the Third Hokage would not even respond.
But Kagami was different. The Uchiha valued strength above all else.
The Sharingan was the foundation. Each additional tomoe marked a higher level. Any Uchiha with three tomoe was already recognized as possessing Jonin level combat power.
"Kagami, is it not inappropriate to say this here?" one elder spoke, his tone cautious, trying to ease the situation.
Kagami looked at him calmly. "When has the Uchiha ever needed to consider the setting before fighting?" he asked, his voice quiet, yet sharp. "Or has your long, comfortable life made you learn from the Hyuga?"
The atmosphere tightened instantly. The rivalry between the Uchiha and the Hyuga was deeply rooted. The Hyuga prided themselves on discipline and bloodline purity. The Uchiha saw them as rigid.
And weak.
Yet without the Mangekyo Sharingan, the Uchiha could no longer fully suppress them.
Kagami's words silenced the elder immediately.
Kagami turned and began walking toward the exit, the sound of his sandals echoing softly through the hall.
Then he stopped. Slowly, he turned his head. His eyes opened fully. Three tomoe spun within them. A terrifying surge of chakra burst outward, pressing against everything around him.
"Clan Head," Kagami said calmly, his voice steady, his gaze unwavering. "I will wait for you for one minute."
A ripple of shock spread through the hall. "…Such overwhelming eye power," someone whispered under their breath. "This is no ordinary three tomoe Sharingan."
*****************
"After all… he's Kagami. Reaching the Mangekyō level is only a matter of time." No one blamed Uchiha Kagami for disrupting the celebration. To them, anything a genius did could be justified, could be forgiven. Even the most rational among the Uchiha ultimately believed in one thing.
Strength.
In front of the clan head's residence lay a wide open space. Fugaku stood there, looking at Kagami with a calm, unreadable expression. "If I may say something…" Fugaku began slowly, "if you truly wish to become clan head, I am willing to train you for a few years, so that you may properly take on that responsibility. You are still too young. You cannot yet handle the affairs of the village. I know you've been influenced by Elder Bokuto, but some things are not as simple as you think."
"You're wrong, Clan Head." Kagami shook his head. "I only want to test my own strength. And…" Uchiha Kagami stepped forward, taking a fighting stance. A faint smile formed on his lips. "This world isn't as complicated as you believe."
A sharp, invisible slash cut through the air.
Fugaku instantly shifted to the side. Behind him, rows of trees collapsed in an instant, crashing down with a deafening roar.
A deep crimson glow surfaced in his eyes. "As a new father…" Fugaku's voice turned cold. "I'll treat this as practice… for Itachi."
The overwhelming power of his gaze spread outward, pressing down on everything around him like a crushing force.
Three years ago, Fugaku defeated Bokuto and became the strongest member of the Uchiha clan. To stand as clan head, he had no weaknesses in ninjutsu, taijutsu, or genjutsu.
With a finely crafted chakra kunai, he clashed against the incoming strike, only for a terrifying force to surge through it. "kagami, you are indeed a genius… but even geniuses need time to grow."
Crack.
The kunai shattered, its surface cut cleanly in two.
Fugaku's pupils shrank sharply. He already knew that Uchiha Kagami possessed a secret technique, one that allowed him to release invisible wind blades from his right eye.
But he never imagined… that can overwelm his weapon coated with chakra.
Thanks to the perception of his Sharingan, Fugaku barely avoided the fatal strike. Still, his hand instinctively moved to his neck, touching the thin line of blood that had already formed. "…How ruthless. Not even sparing your own clan head?"
"Enough talk." Kagami stepped forward, sword raised. A hidden strike like that could have already killed an ordinary jonin. The most terrifying thing about Kagami's ability wasn't only its power, it was also invisibility. Perfect for assassination.
Realizing this, Fugaku's expression hardened. He gripped new kunai.
Their attacks never fully connected. Each clash stopped just short, as if both were predicting the other's next move. To an outsider, it looked like taijutsu.
But in truth, this was a battle of perception, a duel between Sharingan users.
And as the fight continued… Fugaku felt it clearly. His Sharingan… was inferior. What a terrifying talent. 'I can't keep competing with him like this.' Breaking away, Fugaku quickly formed hand seals.
"Fire Style, Great Fireball Jutsu."
Kagami focused his right eye, slicing straight through the massive fireball. Immediately after, dozens of smaller flames shot forward. The Great Fireball was only a feint.
"Fire Style, Phoenix Flower Jutsu."
Each flame was controlled with precision. Hidden among them, shuriken.
'So this is the Phoenix fire style…' That's something people would later associate with Itachi.
But right now, it was Fugaku's skill. Against fire, water would normally be the best counter.
Kagami didn't hesitate. His hands moved quickly, ending with the Tiger seal.
"Fire Style, Great Dragon Flame Jutsu."
A blazing dragon erupted from his mouth, tearing through the incoming flames without losing momentum.
Unlike wide range attacks, this technique focused on power and accuracy.
The fire dragon soared upward, its heat distorting the air, turning the battlefield into a furnace. Using that momentum, Kagami's right eye focused toward Fugaku's face.
And somehow…
That simple motion felt far more dangerous than the massive fire dragon behind it. Fugaku's instincts screamed.
That boy possessed a technique bordering on a Mangekyō ability.
The air split apart with a sharp screech. Invisible slashes rained down.
Boom.
A puff of smoke. Shadow clone. Kagami wasn't surprised.
His Sharingan scanned rapidly, left, right. Then stopped. Above.
He looked up. And was met with a sea of flames descending from the sky.
"Fire Style, Great Fire Annihilation." A raging inferno crashed down like hell itself, threatening to devour everything.
Even Bokuto tensed, chakra gathering at his feet, ready to intervene.
"Brother." Little Shisui cried out in fear, struggling against the clan members holding him back.
In the face of overwhelming flames, Kagami remained calm. His left eye twitched.
Inside his mindscape, even Sukuna watched closely. "…Brat… you're something else…"
Shadows formed around Kagami. Dark, shifting, gathering close to his body.
"What… what kind of ninjutsu is this…"
"The pressure… it's overwhelming…"
The sea of flames began to disappear. Silently. Without pause. As if something invisible was absorbing everything. The fire did not split. It did not scatter.
It was absorbed.
Piece by piece, the raging inferno vanished into the shadows.
Fugaku landed, disbelief filling his eyes. Even after unleashing his full power…
Kagami's right eye surged once more. Fugaku knew what was coming. He clenched his teeth and formed seals again. "Fire Style, Dragon Flame."
Three fire dragons spiraled around him, forming a defensive barrier. An advanced use of fire, not just offense, but defense.
One by one, the dragons were destroyed. And finally, the slashes vanished as well.
For a brief moment, silence. Then— a flash of blue light. "What…"
Kagami appeared in front of him. In his hand, a rapidly spinning sphere of chakra. He slammed it into Fugaku's chest.
BOOM.
The impact sent Fugaku crashing down, carving a massive crater into the ground. Dust and debris filled the air.
"Clan Head."
As the smoke cleared, Fugaku sat in the heart of a massive crater.
His body trembled as he tried to push himself up, but strength failed him. Torn cloth clung to his frame, barely holding together.
And across his chest, a spiraling wound lay bare.
Notes:
So yeah, I changed some previous chapters to better explain Kagami's slash.
Basically, Sukuna's techniques—Dismantle and Cleave—are fueled by cursed energy (negative energy). In this fic, I interpret that as Yin chakra, while Yang chakra is the equivalent of reverse cursed energy (positive energy).
The Uchiha Sharingan is essentially a manifestation of Yin, so I'm using it as the baseline to channel Yin-based techniques (like Sukuna's slash).
Just like how every Mangekyō has a special ability, the difference here is that this one doesn't require the Mangekyō to be used.
I'm not pulling this out of nowhere, because if you remember, there are already two Sharingan abilities so overpowered and they don't require the Mangekyō: Izanagi and Izanami. Both are incredibly broken—you practically have to ban them. One can rewrite destiny, and the other is basically a genjutsu so powerful that the only way to escape it is through character development.