"Let's proceed to the backyard."
Seeing Ren's immediate agreement, Shinku Yūhi nodded with satisfaction and led the way. The space behind the house was a simple, open area, perfect for quiet practice.
"I'm coming too!" Kurenai declared, trotting behind them. She needed to witness her rival's starting point, to understand the challenge she faced. The coveted title of 'older sister' hung in the balance, and intelligence gathering was key.
The three settled in the shade of a mature tree. Shinku adopted a clear, instructive tone. "At its most fundamental, chakra is a composite energy, born from the precise fusion of two components: spiritual energy and physical energy."
He held up one hand. "Physical energy is the life force drawn from the trillions of cells that compose your body. It is the raw fuel of vitality." He raised his other hand. "Spiritual energy is the product of the mind—of experience, of training, of willpower and consciousness. The mental component."
He brought his hands together, interlacing his fingers. "The fusion of these two energies in equal measure creates what we call 'stamina' or 'vitality.' Chakra is not stamina itself. It is a refinement of that stamina, a transformation that extracts and concentrates this blended power into a usable, potent force."
"Since all living beings possess both body and mind—all possess stamina—it means the potential to refine chakra exists within everyone."
"The variance lies in the efficiency of that refinement. The speed, the purity, the volume one can generate from the start. This initial speed is one of the clearest barometers of innate talent a shinobi possesses."
Shinku's explanation was methodical and clear. For Ren, a transmigrator with a conceptual framework of chakra, it wasn't difficult to grasp. The theory aligned with his prior knowledge.
His curiosity, however, was intensely practical. "Speed as a metric," Ren mused aloud. "What's the benchmark? How long for an average person? And what constitutes 'genius'?"
He needed a ruler to measure the effect of his Spiritual Pressure Aptitude reward. Was it a subtle nudge or a seismic shift?
Shinku smiled. Kurenai had asked the exact same question. The siblings shared a competitive pragmatism. "For an average individual with adequate instruction, the first successful refinement typically takes between ten days to a fortnight. A month is considered the upper limit; beyond that, a shinobi career is... unlikely."
"For those blessed with notable talent, the process condenses to mere days. The shorter the time, the brighter the spark of potential."
"For a concrete example," Shinku said, gesturing to his daughter with a touch of paternal pride, "Kurenai here succeeded in a little over two days. A very fine result." He then leaned forward slightly, his voice dropping as if sharing a legend. "The fastest I have ever personally heard of? Sakumo Hatake's son, Kakashi. He refined his first chakra in under a single day. A truly prodigious start."
Ren blinked, his focus snagging on the first point. "Kurenai is considered a genius?" His tone wasn't dismissive, merely surprised, as if re-evaluating a familiar object.
But Kakashi? Under a day? The future 'Copy Ninja,' famed for his Sharingan drain and perpetual lack of chakra, had been that kind of monster as a child? It was a stark reminder of how far the man had… diversified his interests later in life. It underscored a vital lesson: unchecked eccentricity could erode even the greatest foundations. Another reason for Kakashi's later stamina issues had been identified.
"W-what do you mean by that?!" Kurenai spluttered, her moment of pride evaporating under Ren's offhand appraisal. "Why wouldn't I be?!"
"…" Shinku was momentarily speechless. The boy's tangential focus was disorienting. Shouldn't the mention of a record-holder like Kakashi be the main point of fascination?
"The methodology for refinement is as follows…" Shinku proceeded to explain the specific mental and physical exercises—the meditation to sense the body's energy, the focus to gather and blend the two forces, the intent to guide the nascent flow. It was a process of deep internal awareness and delicate manipulation.
After a thorough explanation, he asked, "Any questions?"
He was, he admitted to himself, deeply curious. The boy possessed an unexplained vitality. If the Uzumaki hypothesis was correct, his talent should be significant. A flicker of anticipation stirred within him.
"I understand the theory," Ren said, his expression turning serious. "Let me attempt it. As the elder sibling, my baseline cannot be beneath my imouto's."
He said this with a confidence that felt unshakable. It wasn't just bravado. Beyond the mysterious upgrade from the system, which had left his spiritual senses feeling oddly… acuted, he had the inherent advantage of a matured psyche. His "spiritual energy"—the component born of experience and will—was that of an adult, not a child. That had to count for something.
Closing his eyes, Ren stilled his breathing. He pushed away the chatter of the world, the feeling of the grass beneath him, even the presence of the two watching him. He turned his awareness inward, following Shinku's guidance.
He sought the physical energy—the thrum of life in his cells, the pulse of blood, the latent strength in muscle and bone. Simultaneously, he focused his mind, drawing upon his consciousness, his memories, his unwavering will to survive and thrive in this world. He willed them to meet, to intertwine.
One second. Two. Three.
At around the ten-second mark, Ren felt it. A faint, warm, tingling current, like a trickle of liquid light, manifested deep within his core. It was weak, nascent, but undeniably there. More astonishing than its presence was the instinctive control he had over it. It felt like a new limb he had always possessed but never used—an extension of his own will. With a thought, he guided the slender thread of energy through the pathways of his body, feeling it flow with surprising ease.
He opened his eyes. Bending his index finger, he focused the tiny reservoir of chakra to its tip, concentrating it to a single point, and willed it to manifest externally.
A pinpoint of pale blue light flashed at his fingertip for a fraction of a second before winking out, consumed by the effort.
Chakra, in its raw form, is typically invisible unless released in massive quantities or intensely concentrated, like the famous Rasengan. The spark Ren produced was minuscule, a child's first fumbling strike of a match. But it was light. It was a release.
That fleeting, almost pathetic glimmer was witnessed by both Shinku and Kurenai.
Their reactions were identical: eyes widening in pure, unadulterated shock. Disbelief etched itself onto their features.
He succeeded? Already?
Kurenai's mouth fell open slightly, her earlier indignation replaced by blank astonishment. Two days… versus ten seconds? The disparity wasn't just large; it was a chasm. A cold, sinking feeling touched her heart. Her confident bet about determining seniority through a future spar suddenly felt far less certain.
Shinku's shock ran deeper and along a different vector. The speed of refinement was staggering, yes—it shattered any benchmark he knew aside from maybe Kakashi's mythical feat. But that wasn't the most shocking part.
He refined chakra, and then, without a single moment of practice, he demonstrated precise micro-control and external release?
That wasn't just talent; it was preternatural. It spoke of an innate, intuitive mastery over the energy that others had to painstakingly learn. It was as if the chakra was not just a tool he learned to use, but a native language he already understood perfectly.
"Self-taught… an inherent, instinctive aptitude," Shinku murmured, the pieces clicking into place with definitive force. "He truly is of the Uzumaki lineage. And not just any descendant… one of frighteningly exceptional talent."
His hypothesis was now a near-certainty in his mind. No other explanation fit. Only a clan famed for their monstrous vitality and profound chakra affinity, a clan whose very bodies were naturally attuned to complex chakra manipulation for their sealing arts, could produce such a phenomenon. Ren didn't just have a talent for chakra; he possessed the intrinsic, physiological right to wield it with ease.
The boy wasn't just a potential asset. He was a natural-born prodigy of the highest order.