The moment Kenji got home, he pulled out the chakra metal.
The small wooden box sat on his table, innocuous and unassuming. But inside was material worth more than most ninjas earned in a year. He opened it carefully.
A single black pellet lay cushioned in cloth, roughly the size of a large bean.
Chakra-conductive metal was rare for good reasons. It had perfect chakra affinity, meaning energy flowed through it with almost zero loss. Like a superconductor, but for chakra instead of electricity. The stuff could be shaped with chakra manipulation, had malleable properties similar to gold, and maintained structural integrity once set.
The only downsides were rarity and cost. Otherwise, every ninja would be using chakra metal weapons.
According to his calculations, upgrading the left arm would require about three grams. That left seven for future projects. Not bad.
He detached his left prosthetic arm and laid it on the table. Then he disassembled it, exposing the internal framework. The wooden structure was solid, but the chakra pathways were basic.
That was about to change.
He picked up the metal pellet with his right hand and channeled chakra into it. The black surface began to shimmer. He increased the flow, carefully controlling the energy.
The solid metal started to soften. Not melting, exactly. More like becoming plastic under the influence of chakra. He pulled gently, stretching it like taffy, drawing it out into a thin strand.
The process required absolute focus. He worked slowly, extending the strand thinner and thinner until it was roughly the diameter of a human hair.
Now came the hard part.
He needed to map out a complete chakra pathway system for the arm. Not just the main channels he'd used before, but the full network. Every minor pathway, and connection point, mirroring the real human arm as closely as possible.
He pulled out a medical scroll from his parents' collection. It contained detailed anatomical diagrams, including full chakra pathway maps for every part of the body. He spread it next to the disassembled prosthetic and began comparing.
The human arm had dozens of pathways. Major channels running from shoulder to fingertips, with smaller branches splitting off to serve different muscle groups and functions. The network was intricate, evolved over millennia to distribute chakra efficiently throughout the limb.
Replicating that in wood and metal was going to take hours.
He started at the shoulder connection point, threading the chakra metal wire through pre-drilled channels in the wooden framework. The metal was flexible enough to bend, but once he set it in place with a pulse of chakra, it would harden.
No room for mistakes.
Thread a pathway, check it against the diagram, secure it, move to the next one. His right hand cramped from holding tools for so long. His back ached from hunching over the table. But he kept going.
Hours passed. The afternoon sunlight shifted across the room, turning golden as evening approached.
Finally, as dusk settled over Konoha, he finished. Every major pathway mapped, and every minor branch connected. The left arm now had a complete chakra network embedded in its structure.
He sealed the joint mechanisms, making sure nothing would shift during normal movement. Then he attached the upgraded prosthetic to his shoulder.
The moment chakra flowed into it, the difference was obvious.
Before, using the arm had felt sluggish. Like pushing energy through mud. There was resistance and inefficiency, which resulted in a constant drain on his reserves.
Now? The chakra moved smoothly, almost as easily as through his real right arm. He could feel the pathways conducting energy without any loss.
He tested it by performing hand seals. Ram, snake, tiger. The transitions were natural. He channeled chakra and executed a Transformation Jutsu.
Poof.
When the smoke cleared, he looked like a generic Academy student. He released the jutsu and flexed his puppet fingers, examining them closely.
But there was something he hadn't expected.
As the chakra circulated through the prosthetic's network, he felt a sense of completeness. The arm felt right.
He sat back.
Then he understood.
Chakra was a fusion of physical energy and spiritual energy, combined in equal measure. That meant chakra carried information from both the body and the soul. It was tied to a person's identity on a level deeper than just biology.
He'd seen proof of this in the original timeline. Orochimaru's Living Corpse Reincarnation let him transfer his soul into new bodies while keeping all his jutsu and abilities intact. That shouldn't work if chakra was purely physical. The fact that it did meant chakra contained the imprint of the soul itself.
Same with Edo Tensei. Dead ninjas summoned through that jutsu fought with all their original skills and techniques, despite having artificial bodies made from sacrifices. Their chakra networks were recreated, and that was enough to restore everything.
So what did that mean for his prosthetics?
With only basic pathways, the puppet limbs had been useful tools, nothing more. But now, with a complete chakra network that mimicked real human anatomy, the prosthetic could be recognized by his soul as part of his body.
Kenji looked down at his legs. He'd originally planned to give them only main pathways, since legs weren't used for hand seals or complex jutsu manipulation. Just enough to allow chakra-enhanced movement and wall-walking.
But if incomplete pathways meant his soul was essentially exposed... That couldn't be good.
He didn't know exactly what "soul exposure" would lead to. Maybe nothing. Maybe something catastrophic. But in a world where techniques like Edo Tensei and soul transfer existed, leaving any part of his spiritual self unprotected seemed stupid.
Better safe than sorry.
He glanced out the window. Still evening. He had time.
Kenji grabbed a quick dinner, rice and leftover vegetables from yesterday, eating while he planned the next phase. Then he cleared the table and got back to work.
He pulled out the medical scroll again, this time focusing on the lower body diagrams. The leg pathway system was different from the arm, less emphasis on fine motor control.
He started with the right leg, detaching it and disassembling the framework. Then he began the same process. Shape the metal, thread the pathways, check against the diagram, secure everything in place.
The work was even more exhausting this time. His earlier focus had depleted his mental energy, and now he was running on will alone. But he pushed through, pathway by pathway, and connection by connection.
He worked through the night, barely aware of time passing. At some point, the sky outside shifted from black to deep blue. Dawn was approaching.
Finally, as the first light touched the horizon, he finished the second leg.
Kenji attached both upgraded prosthetics and channeled chakra through them.
His entire body felt whole again. And his chakra reserves surged.
He could feel it clearly. His total capacity had increased significantly, nearly reaching the level he'd had before losing his limbs. Maybe even slightly higher.
That made sense when he thought about it. According to the original Kenji's memories, his chakra had been steadily declining after the injury. That slow drain had been part of what broke the kid's will to live. After the transmigration, Kenji's enhanced spiritual energy had partially restored his reserves, but they'd still been lower than they should be.
He'd assumed physical damage was the cause. Less body mass meant less physical energy, which meant less chakra overall.
But now, with complete chakra pathways integrated into his prosthetics, his capacity had jumped back up. Not quite to the theoretical maximum, but close.
The formula was simple. Chakra equals physical energy plus spiritual energy. His spiritual energy had roughly doubled thanks to the transmigration. Logically, his chakra should have doubled too. But it had only returned to baseline.
Which meant his physical energy was still the limiting factor.
"Guess I'll need to fix that eventually," hee muttered.
White Zetsu. Hashirama cells. The thought had been lurking in the back of his mind since he'd first arrived in this world. Capturing one of those artificial constructs and extracting the First Hokage's genetic material could restore his real body. Maybe even push him beyond normal human limits.
Wood Release would be nice too.
But that was a long-term goal. For now, he had functional limbs and a viable path forward.
He checked the window. Full daylight now. He'd worked straight through the night without realizing it.
He remembered the Third Hokage's request and pulled out blank scrolls and ink. Time to document everything.
The technical manual took another hour to write. He detailed every step of the prosthetic upgrade process. Material preparation, pathway mapping, chakra metal shaping techniques, assembly procedures. He included diagrams copied from the medical scroll, showing exactly where each pathway should be positioned.
This wasn't just for the village. It was knowledge that could save lives and restore broken ninjas to active duty. Worth doing properly.
When he finished, he made a second copy. This one would stay with the Yamanaka clan archives. His parents had left him puppet scrolls. He could leave this for whoever came after him.
By the time he set down his brush, morning had fully arrived.
He stored both scrolls, then stumbled over to his bed. Exhaustion hit him all at once. He'd been awake for over twenty-four hours straight, most of it spent doing chakra manipulation work.
He collapsed onto the mattress and was asleep within seconds.