Shisui had no idea what had happened to Uchiha Seiji.
In his memory, Seiji was always the gentle, slightly timid older brother.Not talented, sure, but endlessly kind—always looking out for Shisui.Cooking meals for him, buying new ninja tools and snacks, listening to his worries… Lately, he'd even started telling funny bedtime stories.
To Shisui, Seiji was the perfect brother, even if he had no real strength.
But now—Shisui's eyes widened in delight. Was his quiet, ordinary brother… actually a genius all along?
Still, in Shisui's heart, Seiji was the one who should be protected by him.
That protective instinct, fused with the Uchiha clan's competitive bloodline, surged within him. And in that moment, Shisui revealed his trump card.
Not even six years old, yet his eyes blazed open—one already carrying two tomoe.
Seiji stroked his chin as he took in the sight of Shisui's Sharingan. His thoughts were sharp, biting:
Some Uchiha had to watch their entire family massacred, their parents slaughtered in front of them, just to awaken these eyes.Others sat at home worrying about the clan's politics until they coughed up blood and popped their Sharingan.
The difference between people… was sometimes wider than the gap between man and mutt.
"Brother…" Shisui's young face twisted with uncharacteristic ferocity, the red glow of his Sharingan warping his cute features into something fierce. "You know the power hidden in these eyes, don't you?"
Seiji blinked, a little surprised—he hadn't expected Shisui to awaken them already. But he still smiled and nodded.
"The Sharingan. The pride of the Uchiha clan."
"It grants three gifts—observation, replication, and hypnosis. With these eyes, one resists illusions, copies ninjutsu and taijutsu, and reads chakra flow to predict movements."
"That's why people say: Never face a Sharingan alone. Especially not a three-tomoe."
Shisui tilted his chin up proudly, the opposite of his usual modest act at the Academy. Here, in front of his brother, he basked in the chance to flaunt his power—and in Seiji's praise.
"So, Brother…" Shisui's Sharingan flared. "Surrender to me."
His genjutsu launched in silence, chakra surging into his technique—his eyes burning bright red.
But Seiji moved faster. He closed his eyes.
Shisui frowned, proud yet strangely sorrowful as he thought to himself: Brother, I'm sorry. Even if you've been hiding strength, without the Sharingan you'll never defeat a genius like me. How pitiful… an Uchiha forced to fight blind.
Yet even as Shisui pitied him, Seiji's hands blurred through seals.
In an instant, Shisui's world plunged into suffocating blackness. His thoughts shattered.
"Genjutsu: Bringer-of-Darkness."
Seiji slowly opened his eyes, smiling faintly as he lectured his stunned little brother:
"This technique was created by the First Hokage to counter Madara Uchiha. Later, a certain… less-than-competent Hokage refined it into something stronger."
"It's a genjutsu most three-tomoe users would struggle to dispel. After all, it carries traces of sealing arts within it."
Shisui's Sharingan spun wildly, straining against the black void—yet saw nothing. His proud eyes, useless.
Watching from afar, Tobirama Senju's face twisted.
What had he just seen?This little Uchiha brat hadn't just stolen his simplified Water Release hand seals—he was now using Tobirama's own modified genjutsu, and flawlessly at that!
The sensation was maddening. The technique was so perfect, so familiar, it was as if Tobirama himself had cast it.
If he hadn't been damn sure he was still a virgin, Tobirama might've suspected he'd fathered this kid with some Uchiha girl years ago.
[Duel Target Detected: Tobirama Senju. You have acquired: Kunai Throwing Technique (Tobirama's Version)!]
The system's chime rang in Seiji's head.
Meanwhile, Shisui dug deep into his memory. His eyes went wide as he whispered into the void:
"A-rank genjutsu… Bringer-of-Darkness."
"Advanced Water-nature chakra transformation… A-rank illusion… simplified seals… Brother, how much are you hiding?"
"This is… beyond a normal jōnin's level."
Shisui's face flushed with shame. He'd bragged about using his full strength—but compared to Seiji? He felt like a child boasting he could topple a mountain.
When Shisui was still dreaming about making chūnin, his "weak" brother had already climbed into the ranks of elite jōnin.
It was humiliating. It stung worse than when Seiji caught him wetting the bed at age four.
The shame of being outclassed, the frustration of their roles reversing, the stubborn pride of a genius—all of it churned violently inside Shisui.
And in that storm, his left Sharingan spun. The single tomoe blossomed into two. His chakra flared, surging like wildfire.
Shisui laughed, raw and manic, as his power swelled:
"HAHAHAHAHA! Brother—I'm still stronger!"
[Detected: Shisui Uchiha harbors intense determination to defeat you. Target bound!]
Seiji heard the system prompt, sensing Shisui's growing chakra. His thoughts sharpened.
So this was the true Uchiha nature: awakening in battle, breaking limits through sheer obsession.
And that laugh—that crazed, unrestrained laughter—proved just how much the Sharingan twisted emotions.
What startled Seiji most was the sheer intensity of Shisui's obsession with surpassing him—enough for the system to bind Shisui as his official rival.
"Then, little brother… don't blame me for going all out."
Seiji unleashed his chakra. Even with his imperfect Senju physique, the reserves dwarfed those of most ninja. More than even a grown Kakashi could muster.
Shisui's bloodshot Sharingan finally pierced through the darkness. His grin split wide with triumph—
But then the black void vanished.
And what he saw froze his smile in place.
The entire training ground had become a vast ocean.
Above it, Seiji stood calmly on the head of a colossal water dragon, looking down on him with a faint, knowing smile.