The charcoal pencil drew a long black stroke across the paper, blotting out the entire area labeled "buffer section." Rinto stared at the blackened patch, his fingertips unconsciously rubbing against the stone workbench. Charcoal dust mixed with dried blood, smearing the edge of the bench black.
He had not slept for two days and two nights.
The semi-open loop he had gotten working in Chapter 39 could barely remain stable without collapsing, and it had problems everywhere: abysmal energy intake efficiency, a natural energy fusion rate below thirty percent, and a cost of thirty percent of his own chakra just to maintain it for twenty minutes. Never mind combat-it could not even be sustained for long periods.
He had revised it three times, and each revision made things messier.
At first, he had tried to improve energy intake efficiency by replacing the single intake channel concentrated in his chest and abdomen with distributed fine channels laid along the superficial branches of his chakra pathways throughout his body. He had hoped to expand the intake area and absorb more natural energy. But it collapsed the moment he tested it. The chakra pathways in different parts of the body varied in thickness, making it impossible to distribute intake evenly among the openings. His arm took in too much before his chest could keep up, instantly throwing the local area out of balance. Petrification patterns spread across the inside of his forearm. He hurriedly triggered the overflow channels and forcibly expelled the unfused natural energy, but a bluish-gray mark remained, painful at the slightest touch.
Later, he added a responsive valve to every distributed intake opening to control how much each absorbed. That evened things out, but energy consumption doubled outright. Maintaining it for ten minutes consumed nearly forty percent of his chakra, making it worse than the previous version.
No matter how he revised it, solving one problem only brought up another. It either collapsed, cost too much, or ran inefficiently.
Rinto set the charcoal pencil on the table, stood up, and went to search the iron cabinet in the corner. Inside were the experiment records he had brought from Konoha, along with records of every failed attempt since fleeing to the Land of Whirlpools. Their pages were frayed from repeated handling. Without turning on a lamp, he leafed through them by the moonlight spilling through the window, his fingertips passing over every backlash he had recorded, every incorrect parameter, every shift in his thinking.
He reached the earliest records of his work on Dynamic Reconstruction. Written there was the core of his breakthrough in Barehanded Jutsu Casting back then: rather than inscribing a ninjutsu structure onto a carrier, he embedded the entire process of deconstruction, fusion, and release into every step of chakra circulation.
His finger suddenly stopped.
Even after he had made his previous circulation system semi-open and added a buffer section, it still fundamentally followed "intake first, fusion second, circulation third." The three steps were separate. Natural energy entered first, fused in the buffer section, then entered the main loop. There was always a time lag. If intake accelerated and fusion failed to keep up, it collapsed; if intake was constrained by fusion, it could not increase, and efficiency naturally remained low.
Just as he had abandoned fixed carriers back then and embedded kekkei genkai fusion into the flow of chakra, why did he have to keep fusion locked inside a buffer section now?
Why could he not embed intake, fusion, and balance into every section of the entire loop?
Rather than building a pipe to feed water into a boiler, every inch of the pipe would take in water, heat it, and deliver steam simultaneously. Every stretch of chakra pathway and every circulation node throughout his body would simultaneously absorb natural energy, complete three-energy fusion, and maintain balance, transforming his entire body from a "container for senjutsu chakra" into a full-chain senjutsu fusion reactor.
Rinto shut the experiment records and rushed back to the stone workbench. Forgetting even to turn on a lamp, he grabbed a fresh sheet of scratch paper in the moonlight and drove his charcoal pencil across it, slashing through the semi-open loop he had drawn countless times before.
The entire previous structure was scrapped.
Starting from the chakra source in his dantian, he redrew the channels. There were no separate intake pipes, no centralized buffer section, and no fixed fusion zone. Miniature intake, fusion, and balance units were embedded into the responsive structures of every stretch of chakra pathway. With every inch the chakra flowed, it would simultaneously absorb a trace of natural energy and complete fusion. Excess energy would be discharged directly through distributed overflow outlets, resolving the problems of timing discrepancies and local imbalances at their root.
He drew until daybreak, only putting down the final stroke when the morning light outside washed the paper pale. The entire sheet was densely covered. Gone were the clearly divided channels of before; all that remained were miniature units embedded in the chakra pathways and responsive logic linking the entire chain.
The logic worked, but the risks were countless times greater than before.
If the previous loop collapsed, the worst it could cause was localized backlash, and he could still limit the damage with overflow channels. In this full-chain fusion system, however, if a single miniature unit went wrong, the imbalance would instantly spread throughout his body along the entire loop. At best, the backlash would destroy all his chakra pathways; at worst, his whole body would petrify outright, leaving no chance to save him.
Rinto did not hesitate. In all his years of research, he had never stopped for fear of backlash. He simply laid the emergency sealing tags he had prepared beside his feet, one after another, and inscribed emergency flow-cutoff anchors in advance at several critical chakra pathways throughout his body. If anything went wrong, he could immediately lock down the local pathways and prevent a total collapse.
Once everything was ready, he walked to the open space in the middle of the laboratory, closed his eyes, and took a deep breath. He cleared all the cluttered thoughts from his mind, leaving only the full-chain circulation structure he had just drawn.
Chakra slowly rose from his dantian and began circulating through his body's chakra pathways along the newly designed channels. The miniature units in every stretch of pathway activated simultaneously, their responsive structures adjusting to the chakra's flow speed. The entire loop started smoothly, without turbulence or stalling.
Once the loop stabilized, he did not rush to draw in natural energy. He first circulated his chakra over and over, thoroughly familiarizing himself with how the units in each section worked together and how their responsive structures reacted. Only after confirming there were no logical flaws did he slowly open up the intake of natural energy.
Instead of drawing it into his body through a concentrated point as before, countless miniature intake openings opened simultaneously along the chakra pathways throughout his body. Extremely fine strands of natural energy seeped into the chakra loop like drizzle.
Every strand of natural energy was immediately caught by the miniature unit in its stretch of pathway and fused simultaneously with physical and spiritual energy. Balance stabilized within the tiniest margins. The fused senjutsu chakra immediately circulated throughout his body, while excess, incompletely fused natural energy was discharged directly through the nearest overflow outlet. It could neither accumulate nor disrupt the loop.
At first, his nerves remained taut, ready to deal with an imbalance at any moment. Even his fingertips were clenched, prepared to trigger the emergency anchors.
But one minute passed, then five, then ten.
The loop grew increasingly stable. Natural energy intake and fusion were completely synchronized, and senjutsu chakra flowed smoothly through his pathways, fully integrated with his own chakra, without the slightest sluggishness or sign of imbalance. He did not even need to control it deliberately. The miniature units automatically adjusted intake volume and fusion rhythm, adapting to changes in the loop.
Rinto slowly opened his eyes and raised his hand.
Faint, almost invisible senjutsu chakra wreathed his fingertips. It lacked the brilliant light he had deliberately concentrated before, yet carried a weighty presence that faintly resonated with the surrounding natural energy. He could clearly sense the natural energy flowing through the air around him like water. Whenever he wished, he could draw it over and merge it into the loop.
He tried increasing natural energy intake, doubling it, then doubling it again.
The circulation system handled it steadily. The miniature units adjusted their openings in unison, and fusion speed rose alongside intake volume. There was no imbalance, no loss of control. Senjutsu chakra accumulated faster and faster, and he could feel that brimming strength throughout his body. It was completely different from the "borrowed power" of Carrier-Version Senjutsu-this was senjutsu that belonged entirely to him, integrated with his own chakra and his to command freely.
Rinto's fingertips shifted. The instant the thought arose, senjutsu chakra had already gathered at them. He casually flicked out an extremely thin senjutsu wind blade. There was no thunderous blast through the air, only a soft hiss as the high-density sealing metal plate piled in the opposite corner, half a finger thick, was sliced cleanly in two. The cut was as smooth as a mirror, without even a stray fragment scattering.
Speed, power, precision-all surpassed his previous Carrier-Version Senjutsu by more than an order of magnitude. Most importantly, there was no windup or preparation time. The jutsu formed with a thought, as freely as his ordinary barehanded ninjutsu.
He tried Senjutsu Dust Release next. A faint white light appeared at his fingertips. Unlike the brilliant light that previously required half a second of advance concentration, it was extremely subdued and condensed. With a casual push, a piece of basalt in front of him used for testing silently vanished into nothing. Not even a wisp of dust rose, and the surrounding floor and stone walls were completely unaffected. Its compression precision had reached the limit.
It worked.
True Barehanded Senjutsu, entirely his own, had worked.
No carrier, no anchors inscribed in advance, no delay, no risk of backlash. He could wield it freely, and it fit perfectly with his Dynamic Reconstruction system. Every flaw in Carrier-Version Senjutsu that had troubled him for months was resolved.
Standing where he was and maintaining his senjutsu state, Rinto tested more than a dozen other ninjutsu. Senjutsu Ice Release, Senjutsu Lava Release, Senjutsu Lightning Release-all activated instantly, with power and precision far beyond before. He could even adjust his chakra flow while maintaining the senjutsu loop, without that previous feeling of separation between senjutsu and ninjutsu.
Only after completing every test he could think of did he slowly withdraw his senjutsu chakra and stop the loop.
There was none of the total exhaustion he had previously felt after dispersing senjutsu. The loop stopped steadily and smoothly, without the slightest discomfort in his chakra pathways. Even his chakra consumption was far lower than he had expected.
He walked to the stone workbench, picked up the thick volume of core experiment records, opened a fresh page, and began writing carefully with the charcoal pencil. From the core logic of the full-chain loop to the parameters of every channel, then the pitfalls encountered during trial and error, the lessons from backlash, and the final structure, he recorded everything meticulously, leaving out not even the smallest adjustment.
Only when he had recorded everything and closed the book did he realize the sun outside had already climbed overhead. Noon sunlight shone through the ventilation opening, casting long patches of light on the floor. The oil lamp on the table had long since burned dry, its charred wick curled inside the bowl. The dry flatbread beside it was still the one he had taken out yesterday morning, untouched and hard as a rock.
Only then did he feel his empty stomach cramping with pain, his terribly gritty eyes, and every bone in his body seemingly stiffened in place. The exhaustion of staying awake for two days and two nights surged over him the instant his nerves fully relaxed.
Yet he did not feel tired at all.
The past several months of trial and error, backlash, bottlenecks, and dead ends-all the frustration, defeat, and breakdowns after pushing himself to the limit-had finally yielded a result at this moment.
Rinto picked up the dry flatbread, walked to the laboratory entrance, and pushed open the stone door. The afternoon sea breeze swept over his face, carrying a salty dampness. He bit into the flatbread and swallowed it with the sea breeze, his gaze sweeping across the entire deserted island and the shimmering sea beyond.
Before, he had kept to this island because it was the only place where he could research in peace, afraid of being disturbed or interrupted by pursuers. But now, with Barehanded Senjutsu in his grasp and the ability to fully integrate senjutsu with Dynamic Reconstruction, even if ten more Orochimarus came, or another Konoha extermination squad, he had the confidence to sweep the trouble away, turn around, and resume his research.
He finished gnawing through the flatbread and returned to the laboratory without resting or celebrating. He merely placed the newly drawn full-chain circulation plans carefully inside a sealed metal box, then picked up the charcoal pencil and wrote a new research title on a fresh sheet of scratch paper.
Instantaneous fusion of senjutsu and kekkei genkai reconstruction.
His path had only just begun.