Hiroki was jogging.
He didn't stop—walking back and forth across the stream as easily as if it were solid ground. He even crouched down to touch the cold water with his fingers, the movement smooth and effortless, as natural as breathing.
It worked again.
No—this wasn't just success. It was mastery. He moved like someone who'd practiced the technique countless times.
Nawaki's jaw dropped, his morning confidence shattered into disbelief.Hiroki was two years younger than him!
Kushina stood frozen, staring at the boy calmly walking on water, completely speechless.
"How… did you do that?" Nawaki finally blurted out, his voice tinged with frustration.
Hiroki stepped back onto the bank, his expression calm as ever.
The real answer was simple: he'd "cheated" with his system code.
But that wasn't exactly something you could teach kids, so after a brief thought, Hiroki simply said, "Work hard, think deeply, and learn."
He turned his gaze toward them. "Just now, Orochimaru-sensei said climbing trees takes one-third of the chakra needed for a Transformation Technique, and water walking takes two-thirds." He extended his right hand, palm open. "But that's still too vague. Relying only on feeling is unreliable—we need a visible, measurable standard."
Slowly, chakra gathered in his palm.
A soft, light-blue glow appeared—steady, calm, and perfectly round, no larger than a thumbnail, floating quietly above his skin.
"The total chakra needed for a basic Transformation Technique equals one hundred units," Hiroki explained. "I call these units ka. What you see now is one ka—think of it like a ruler's centimeter or a gram on a scale."
Of course, maintaining that precise amount was easy for Hiroki.He'd simply written a command in his inner "code": output one ka per second.No more, no less—his system handled the precision automatically.
Retracting the chakra, Hiroki looked at his teammates. "Now, you try. Just one ka—no need for more."
Kushina and Nawaki exchanged a glance, both unwilling to admit defeat.
Kushina inhaled sharply and mimicked Hiroki, channeling chakra into her palm.
A bright blue flame-like burst flared to life, expanding uncontrollably to the size of a fist before shrinking and flickering wildly, pulsing like an unstable fire.
Nawaki gritted his teeth and tried as well. His chakra sphere held its shape a little better but still flickered erratically—like a faulty light bulb.
Sweat beaded on both their foreheads.
This "simple" one-ka output was harder than climbing a tree.
"Interesting," Orochimaru's voice broke the silence—soft, cold, curious.
His golden eyes locked on Hiroki. "Hiroki-kun, do you realize what you just did?"
Without waiting for an answer, he continued:
"You've created something unprecedented—a quantitative system for chakra control."
"Since Konoha was founded, countless prodigies have tried to refine chakra training. Yet all teaching has relied on vague advice—'practice more,' 'feel it,' 'trust your instincts.' Even the First Hokage never managed to turn chakra control into a measurable science."
"But you, Hiroki—you've done it. With a single unit, ka, you've solved that problem. From today forward, chakra control can be measured, evaluated, and improved."
He paused, a flicker of awe in his eyes."…But is this truly your own idea?"
Orochimaru's mind raced. It sounded like something the Second Hokage would've devised—the man who created countless jutsu and founded the Ninja Academy itself. But even in all those years, the Second had never introduced such a system. Would he have hidden it, telling only one student? Unlikely.
Which left only one conclusion: Hiroki, the Second Hokage's legacy, was a genius in his own right.
Turning back to the others, Orochimaru said, "Uzumaki Kushina, based on Hiroki's standard, your chakra output peaked at about six ka per second and dropped to as low as 0.1."
Kushina's face turned crimson.
"Nawaki, your average was 2.5 ka, fluctuating between 0.8 and 4.2. Your control's better than Kushina's, but still unstable."
The two students stared, wide-eyed.You could calculate chakra like that?
Hiroki, too, was surprised.How did Orochimaru measure their output so precisely? His system didn't show Orochimaru's name anywhere.Was he guessing? Or could Orochimaru actually sense chakra with such accuracy?
While Hiroki pondered, Orochimaru continued his lesson.
"Your problem isn't chakra quantity—it's instability. Your output fluctuates too much, like a faucet with uneven water flow. If it's unstable, it can't support your weight on a wall or surface."
Seeing their confusion, Orochimaru added, "We can express this instability numerically."He glanced at Hiroki. "Hiroki-kun, how would you define this value?"
Snapped from his thoughts, Hiroki answered after a short pause, "It could be called a fluctuation value—or in mathematical terms, standard deviation. It measures how much chakra output varies from the target value. The smaller the deviation, the better the control."
"Excellent." Orochimaru smiled slightly. "Then, by that definition…"
He extended his palm. A pale-blue sphere appeared, perfectly still.
"My standard deviation is about ±0.02 ka—almost negligible.And you, Hiroki-kun…"
He paused, a strange light flickering in his eyes.
"From my perception, your chakra output doesn't fluctuate at all. Your standard deviation is effectively zero."
Zero.
No fluctuation.
Was that even humanly possible?
Even Orochimaru couldn't achieve that kind of precision.He prided himself on his control, rivaled only by Tsunade or his teacher, the Third Hokage. Yet Hiroki—still a child—had surpassed that.
Orochimaru could only think: So this is the Second Hokage's chosen heir…
He turned back to the group.
"Nawaki, by our definition, your standard deviation is ±1.7 ka. Kushina, yours is ±2.9."
"To climb trees, your deviation must be within ±0.5. For water walking, ±0.2."
The unfamiliar numbers and terms opened an entirely new perspective for the two young ninjas.It felt like they were back in school—but now the subject was math disguised as chakra training.
Seriously? Ninjas have to calculate now?
Still, for the first time, they could see the difference between themselves and Hiroki—not just as "better" or "worse," but as exact, measurable data.
Zero.No fluctuation.How was that even possible?
"But…" Nawaki frowned. "If it's just about control, then people with more chakra are at a disadvantage, right? A ninja's strength isn't only about precision."
"Good question." Orochimaru actually smiled—genuinely impressed.
"That's the brilliance of Hiroki-kun's system. It doesn't just quantify control—it gives us a way to evaluate a ninja's overall chakra performance."
He raised three fingers.
"There are three core chakra indicators."
"First—total chakra capacity." His gaze shifted to Kushina. "A typical Chunin has between six to twelve thousand units. You, Uzumaki Kushina, have about twenty-five thousand—thanks to your clan's bloodline."
Kushina's eyes sparkled with pride.
"Nawaki, you're at roughly eighteen and a half thousand—above average for your rank."
Nawaki grinned and glanced at Hiroki, eager to compare.
Orochimaru turned to Hiroki."Your total chakra is lower—about thirty-two hundred. That limits your endurance and the number of jutsu you can cast. For instance, a Lightning Release: False Darkness requires around three thousand units. One use would nearly deplete you."
Hiroki nodded. That matched his calculations.
"Second," Orochimaru continued, "is maximum extraction rate—the amount of chakra you can draw instantly. Like the width of a pipe determines water flow, this defines your burst power. Even with a large reservoir, if extraction is slow, you can't perform high-level jutsu efficiently."
"Third—control accuracy, what Hiroki calls standard deviation. It determines how efficiently chakra is used and how precisely you can execute techniques."
He lowered his hand and gave his familiar, unreadable smile."Total capacity, extraction speed, and control accuracy. These three together define a ninja's chakra efficiency. From now on, your training will focus on improving all three."
Kushina's hand shot up, eyes bright."Sensei! If we follow Hiroki's system, does that mean we can create individual training plans?"
"Exactly," Orochimaru said approvingly. "Kushina, you have plenty of chakra but poor control, so you'll focus on precision. Hiroki, you have less chakra, so your training will focus on increasing your capacity and refining extraction speed."
"That," he concluded, "is the power of quantification."
Nawaki clenched his fists, fire returning to his eyes. "Then I'll train until my standard deviation is lower than Hiroki's! I'll beat you at control!"
"Me too!" Kushina added fiercely. "I might be ±2.9 now, but I'll get it below ±0.1!"
Watching their renewed determination, Orochimaru smiled faintly—but his eyes lingered on Hiroki.
Cheerful, straightforward kids like Kushina and Nawaki were easy to teach.But Hiroki… Hiroki was different. Too calm. Too precise. Too secretive.
What else are you hiding? Orochimaru wondered.
Finally, he said, "Hiroki-kun, I'll compile your theory into a formal training framework and report it to the Third Hokage. If approved, it will revolutionize Konoha's ninja education."
He paused, voice deepening."This system should bear your name—the Hiroki Theory."
Hiroki blinked, stunned.
He'd only wanted an easier way to code chakra parameters.He hadn't meant to start a scientific revolution.
Orochimaru's praise left him speechless, so he quickly changed the subject."Uh… let's finish the mission first!"
He reached over and picked up the cat, Tiger, the same one from their earlier task.
Just then, an Anbu appeared beside them in a flash.
"Report! Lord Orochimaru, the Third Hokage requests your presence. Bring Team Two to the Hokage's office immediately."
Orochimaru's eyes narrowed.
Now? At this hour?