The Rebirth Core consisted of three crucial parts: the outer shell, the internal chakra-bearing flesh, and the nutrient solution that sustained and empowered the whole construct.
The outer shell served as armor, protecting the delicate contents within. However, it was far more than just a casing—it needed to be capable of conducting chakra, housing meridians akin to a human body. Without this, the Rebirth Core would be nothing more than a lump of wood, unable to cast even the simplest ninjutsu.
This was the same principle behind the Substitution Technique, where a ninja would replace themselves with a plant, animal, or object that could temporarily mimic their chakra signature and withstand a small portion of chakra-based stress. In the case of Sasori, the infamous puppet master of Sunagakure, the shell had merely been constructed from ordinary puppet-grade wood. Akira, however, had no intention of spending unnecessary effort on this part either. He utilized leftover puppet-crafting materials from Sasori's scrolls without hesitation, repurposing the best of what the master left behind.
The real challenge lay in the second component—the chemical nutrient solution. This fluid was to act as both blood and sustenance. It needed to maintain the living tissue's activity and continuously feed it energy to create chakra. While living ninjas consumed food and converted it into chakra, the Rebirth Core lacked such an ability. It could not eat, could not digest. Its sustenance had to be external.
Sasori had not perfected this step before his demise. But Akira, with his extensive background in biology, botany, and chemistry from his previous life, saw the path forward. Compared to preserving human tissue, keeping plant matter alive seemed far simpler.
He delved into Konoha's Library, poring over ancient scrolls, research papers, and agricultural texts. With each day, his understanding of the flora in this world deepened. He cross-referenced his knowledge of soilless cultivation from his former life with chakra-based plant care in this one. The answer slowly took shape.
After adjusting Sasori's original formula for animal flesh, Akira carefully rewrote it for plant tissue. The ingredients were not rare, mostly fertilizers, mineral compounds, and innocuous materials no one would bat an eye at. To others, it might have seemed like Akira—the best medical ninja in Konoha—was simply growing his own fresh medicinal herbs. Entirely within reason.
With the final solution prepared, Akira tested it. He took a branch from his tree clone deep within the Forest of Death, placed it in the solution—and watched it die.
Confusion struck him. His formula should have worked. Even with minor errors, the branch should have lasted longer. Then, a realization hit him like a bolt of lightning.
Blood vessels.
Human tissue had them. Trees, however, did not. Their xylem and phloem were microscopic compared to human veins. The nutrient solution simply couldn't reach deep enough through mere soaking.
He needed roots.
Akira quickly returned to the Forest of Death, unearthed a portion of the root system from his clone, and grafted it together with a branch. Using Earth Release to avoid disturbing too much of the terrain, he retrieved just enough to experiment without harming the whole.
Back at his home, he used precise medical ninjutsu to bind the tissues together and immersed the new graft into his refined nutrient solution. This time, it worked. Under the gaze of his Sharingan, Akira saw no chakra loss. No decay. The tissue lived.
Refining the formula further for efficiency, Akira prepared to construct his Rebirth Core. He harvested a section of the heartwood—the area within the clone where chakra was most densely concentrated, an unexpected oddity. In theory, a tree's energy should circulate near its bark. But Akira's clone was born from Infinite Rebirth, a jutsu that had its own strange logic. The tree's chakra pulse came from its center.
He carved out a chunk of the heartwood with root still attached, soaked it in the perfected nutrient solution, and encased it in the puppet shell. No chakra leakage. No decline in liveliness.
Now came the final and most delicate step: inscribing the technique into the shell.
The technique wasn't just a simple seal. It was a symphony of formulas—one to extract chakra, another to channel chakra threads outward for control, and multiple sub-techniques for artificial senses: vision, hearing, touch, and smell. To any ordinary puppet master, this would be an almost impossible endeavor.
But Akira was no ordinary puppet master.
With Sharingan-guided precision, a surgeon's steady hand, and a scholar's depth of knowledge, Akira etched every line and symbol flawlessly. Hours passed. Then days. At last, the array was complete.
He assembled the shell, placed the chakra-bearing heartwood inside, poured in the nutrient solution, and sealed it shut. With a deep breath, Akira began the hand seals. The complexity rivaled even the Dead Demon Consuming Seal. One misstep, and the whole core would fail.
As the final seal was completed, the Rebirth Core pulsed.
Light flared from the inscriptions, then gradually faded, leaving behind a single kanji etched on each end of the cylinder.
Life.
Akira gasped as the senses flooded his mind. The previously silent tree clone now spoke in his thoughts—smells, sights, sounds, even the sensation of wind brushing past bark. For the first time, his creation lived.
Chakra threads extended from the Rebirth Core like delicate fingers, mimicking limbs. They flexed, gripped, moved at his command. It walked, slow and lumbering, but obedient. It lived.
This Rebirth Core was massive—far larger than Sasori's version. A necessity, since tree chakra was weak compared to human chakra. Still, Akira estimated that it contained only one-tenth of the clone's total chakra, barely enough to match a Genin's reserves.
Not enough to fight.
But he had already thought of that.
Akira had inscribed the Yin Seal onto the Rebirth Core—a technique to store chakra passively over time. Like Tsunade's famed Strength of a Hundred Seal, it would gather energy when dormant, then unleash it in combat for devastating power.
The puppet to house this core? The reformed Third Kazekage.
Sasori had distorted his appearance, reducing the great Kage to a twisted caricature. Akira couldn't understand it. If Sasori could make puppets as lifelike as himself, why make the rest so hideous?
Art, in Akira's view, should honor what was, not desecrate it.
So, he remade the puppet—restoring dignity, beauty, and humanity to the shell of a legend. The Third Kazekage would rise again. Not as a tool of terror, but as a refined blade of resurrection.
And at its heart, the Rebirth Core beat quietly, full of promise, power, and purpose.
Although the puppet was crafted with care and a sense of beauty, Akira did not attempt to restore the Third Kazekage to his original appearance. Instead, he gave the puppet the visage of Sasori.
This decision was made for several reasons. First, Akira had no accurate visual reference of the Third Kazekage while alive. Without a concrete image to draw from, even if he tried, the end result would never be a faithful reconstruction. Sasori, however, was different. Akira had seen him up close, memorized every contour of his face, every nuance of his expression. With the Mangekyo Sharingan, Akira could mimic even the most intricate details, allowing him to recreate Sasori's likeness with eerie perfection.
There was another, more strategic consideration. In the future, Akira might need to assume the identity of Sasori. Having a stand-in, a replica to take his place when necessary, would be immensely useful. It could prevent situations where both he and Sasori would need to appear simultaneously—an impossible scenario for a lone man.
He stared into a mirror, carefully adjusting the puppet's features, smoothing the angles, deepening the eyes, perfecting the expression until it was indistinguishable from the real Sasori. A ghost resurrected in wood and chakra.
Once the cosmetic work was complete, Akira inserted the Rebirth Core into the puppet's chest cavity. Chakra threads extended outward, writhing like living tendrils. Some wrapped tightly around the puppet's original chakra core, integrating it with the new Rebirth Core. This would allow the puppet to access and wield the Kazekage's old ninjutsu. Other threads snaked through the puppet's limbs, joints, and sensory components, restoring function to eyes that hadn't seen in years, ears that hadn't heard a whisper, and limbs that had long since forgotten how to move.
Then, something incredible happened. The eyes flickered to life.
What had been a lifeless husk was now something else entirely. Though still cold, the puppet's eyes shimmered with a spark of animation, an unsettling mimicry of life. It stood slowly, without command, without guidance. It moved on its own.
The new Sasori puppet was slightly taller than the original, owing to the Third Kazekage's natural height. Ironically, after Akira had healed the original Sasori's body with Yang Release illusions, his own height had increased as well. Now, puppet and man stood nearly identical, twin phantoms of an identity reborn.
Unlike Sasori, who had carelessly left his Rebirth Core exposed in the open for convenience—probably to facilitate easier control of multiple puppets—Akira was not so reckless. His Rebirth Core was deeply embedded and shielded by reinforced shell layers within the puppet's body. He had learned from Sasori's fatal mistake.
The size of the Rebirth Core forced Akira to install it vertically and relocate the original chakra core to accommodate the internal layout. No external opening was left. No weakness unguarded.
Akira also had a revelation. Perhaps he didn't even need chakra threads to control his puppets. With the Third Kazekage's innate Magnet Release and Sasori's puppeteering knowledge at his disposal, he might be able to manipulate the puppets using Iron Sand instead. Few in the world possessed Magnet Release. Even in Sunagakure, this power was rare and misunderstood. But Akira remembered something—Shinki, Gaara's adopted son in the Boruto era. He was a puppeteer who used Magnet Release to great effect.
If Shinki could do it, why not Akira?
Eager to test his theory, Akira used the Flying Thunder God technique to teleport to the desolate battle-scarred terrain of Kikyo Mountain. The land, though cleansed of bodies and debris, still carried the quiet aftermath of war. No one would disturb him here.
He summoned the Sasori puppet and began. Scroll in hand, he unfurled a sealed puppet and infused it with chakra. Most of the Iron Sand had been lost during his earlier battle with Sasori, scattered across the battlefield. And Iron Sand was not something one could easily find at a marketplace. Fortunately, some residue remained within the puppet's body—enough for a trial.
Akira directed the remaining Iron Sand to adhere to the puppet's internal mechanisms. With a steady hand, he guided the chakra through the sand, commanding the puppet to move.
It responded—stiff at first, clumsy, but it moved. Like a marionette learning to dance again.
With time and practice, the movements smoothed out. Akira's control grew finer, more delicate. He activated the puppet's mechanisms, drew out its hidden weapons, triggered its sensory systems. Everything responded.
Now that he was comfortable with one puppet, Akira pushed further. Two puppets. Then three. Four. Ten.
Ten puppets danced beneath his will, the limit Sasori had once reached. But Akira felt untapped potential bubbling beneath the surface. Sasori had been limited by his ten fingers. Akira had no such restriction—not when his Rebirth Core could release dozens of chakra threads. In time, he could surpass Sasori's famed Hundred Puppet Performance.
However, the success was short-lived. The chakra within the Rebirth Core began to wane. The Iron Sand became erratic. Puppets collapsed.
Akira sighed. As expected, the Rebirth Core couldn't keep up.
But he had anticipated this.
He placed his hand on the core and began channeling chakra into the Yin Seal engraved upon it. To his surprise, the transfer was smooth. Normally, foreign chakra would be rejected by a person—or a construct—due to incompatibility.
But the Rebirth Core had been made from Akira's Tree Clone. It was, in essence, an extension of his own being. Its will, its chakra nature—everything was part of him. It welcomed his chakra like water returned to its source.
He transferred half of his reserves, then released the seal.
A surge of power erupted. The Rebirth Core thrummed with life. Chakra flooded the puppet's systems. The Iron Sand reformed. Puppets rose again, quicker, stronger.
With the magnetic field bolstered, the precision and speed of their movements increased. It was a sight to behold.
Akira folded his arms, watching his ten puppets whirl and twirl like wraiths on invisible strings.
Now, he could summon this puppet-Sasori anytime. And if it faltered, he could recharge it with his own chakra.
The clone had evolved. It was no longer a mere tool—it was a phantom general, ready to command an army of death at a single whisper from its master.
And Akira, standing beneath the faded war skies of Kikyo Mountain, could not help but smile.
He was ready.