Fire Style: Great Fireball Jutsu.
It was a signature technique of the Uchiha clan, but at its core, it was still just a C-rank ninjutsu. Even in the hands of a genius like Uchiha Itachi, the fireball's diameter rarely exceeded five meters.
And yet—Senju Haruto had casually unleashed one over twenty meters wide.
If he hadn't pulled back at the last second, Sasuke might have ended up in the hospital with severe burns.
Watching this unfold through his Telescope Technique, the Third Hokage, Sarutobi Hiruzen, couldn't help but draw in a sharp breath.
From Haruto's hand-seal speed alone, it was obvious he wasn't practiced in this jutsu—there wasn't even a hint that he'd trained it before. It was as if he'd simply seen Sasuke perform it, and then copied it on the spot.
Of course, having a massive chakra reserve wasn't unheard of. Uzumaki Naruto's chakra alone far surpassed that of most jōnin. But Naruto had no real talent—he couldn't even produce a proper Clone Technique.
"For a shinobi, raw chakra alone isn't enough… The ability to grasp a jutsu in a single glance—that's what's truly terrifying."
Hiruzen's eyes narrowed as he stared at Haruto through the crystal ball. Another figure came to mind—one known as the Copy Ninja.
Hatake Kakashi.
"Thanks to his Sharingan, Kakashi can instantly replicate an enemy's ninjutsu and make it his own. But that style of combat is a drain on his chakra."
"For Senju Haruto, his copying speed might not match Kakashi's—but he bears none of the chakra strain."
And most importantly…
Haruto could effortlessly amplify the enemy's jutsu to an entirely higher level.
It wasn't an exaggeration—just now, with chakra alone, he had taken a C-rank Great Fireball and elevated it to at least B-rank.
"Wait…"
A more chilling thought struck Hiruzen.
This was just a school spar, not a battle to the death. Haruto's goal wasn't to defeat Sasuke outright, but to show him the gap between them—force him to yield.
"…He wasn't even going all out."
Hiruzen's lips tightened. If Haruto unleashed his full chakra reserves, just how big could that fireball get? Thirty meters? Fifty? Something even more absurd?
The Senju brat was downright terrifying.
"How many chakra natures does he even have?"
Another suspicion jolted through Hiruzen, making his eyes widen.
Could Senju Haruto… use Wood Release?
Meanwhile, back on the academy training field—
Seeing Sasuke sitting frozen on the ground, still looking shell-shocked, Haruto immediately released his jutsu.
Fwoosh!
The massive fireball unraveled midair, dissipating into harmless smoke.
Everyone else just stared, dumbstruck, like they'd just seen a ghost.
They'd always thought Sasuke's Great Fireball was impressive enough. But Haruto's?
That wasn't ninjutsu. That was senjutsu.
As for Mizuki and Iruka, the two chūnin understood better than anyone just how terrifying Haruto was. This wasn't talent—this was monstrous. An unreasonable, impossible monster.
Iruka was so stunned, he even forgot about the Seal of Reconciliation entirely.
Does this guy even need to attend the academy?
"Iruka-sensei, can we wrap this up?" Haruto asked casually, not the least bit concerned with Iruka's expression. "Uchiha-kun doesn't seem to want to continue."
Continue?
Still want to continue?
If I were Uchiha Sasuke, I'd be wetting myself right now.
Several of Iruka's students gave Sasuke pitying looks, wondering how deep the psychological scar from this would go.
"Uh…" Iruka snapped back to reality at Haruto's voice. He glanced at the roster, then stammered, "R-right… Sparring session over… Sen–Senju-kun, the Seal… Seal of Reconciliation."
"Mm."
Haruto replied briskly, stepping up to Sasuke and holding out a hand.
Sasuke looked at Haruto, then at the hand, mind blank.
He didn't take it. Instead, he tried to push himself up. He failed. Twice.
On his third attempt, he finally managed to stand—but his voice was gone, stolen by the shock of Haruto's fireball.
Moving stiffly, Sasuke formed the Seal of Reconciliation with Haruto.
Who am I? Where am I? What am I doing? What just happened? And where's my brother?
Mizuki stared blankly at the scene. He had thought he'd feel jealous, seeing such an overwhelming display of talent.
Instead, after witnessing it firsthand, he felt… uncertain of reality itself.
Am I really a chūnin? Is this really Haruto's first day at the academy? Is this even the real world?
What is ninjutsu?What is a ninja?
"Amazing… honestly unbelievable." Iruka took a deep breath, unable to stop himself from commenting. "Senju-kun, that Great Fireball was outrageous. You haven't been secretly practicing it at home for the past five years, have you?"
It was the only explanation he could think of for such a display.
Sasuke had been incredibly unlucky to run into Haruto's strongest field.
No—that had to be the truth. He needed it to be the truth, to keep his worldview intact.
But Haruto just shook his head. "Nope. That was my first time using ninjutsu."
"I saw Uchiha-kun's seals and thought I'd try it. Didn't expect it to work."
"…What?!"
Iruka and Mizuki's eyes flew wide, their minds going blank.
First time using ninjutsu?
Come again—translate that for me. What do you mean, first time? What do you mean, 'didn't expect it to work'?
What kind of divine-level bragging was this?
But Haruto wasn't pretending to be humble—he truly meant it. This was his first time, his first attempt.
Must be thanks to that reward from earlier, Haruto realized suddenly, understanding now what "mastery" really meant.
With simple jutsu like this, all he needed was a single glance to learn them.
Does this mean… from now on, for any jutsu… if I see it once…
Just as curiosity sparked in his mind, the system's auxiliary prompt sounded in his ear:
"'Mastery' does not represent the absolute limit. View detailed description?"