In reality, creating a puppet of Sara would be the fastest way to gain control over the seal.
However, what Ryuji wanted was not merely a reliable key to the seal; he needed a key that could be freely passed down through future generations.
Not through bloodlines, but through a process of selection.
Similar to how the Kazekage is elected, the holder of the key must be someone recognized and accepted by the entire village.
After all, the Dragon Vein was the energy source for the entire Mechanical City. If something went wrong with it, the entire city would be crippled.
If it were passed down through a specific bloodline over generations, it was all too easy for the village to eventually fall under the control of a single family, becoming their private property. This would be detrimental to Sunagakure's future development.
With his understanding of the seal's principles, having the Observation Device conduct reverse analysis would allow him to deduce a method without much delay.
Ryuji set up a project for the Dragon Vein seal analysis in the Observation Device, letting it work on the solution.
Meanwhile, he turned his attention to Yamato's arm.
The arm was preserved extremely well, as if just severed, with blood still seeming fresh and the cells brimming with life force.
He placed the arm under the Observation Device for observation and analysis, aiming to reconstruct a model of Yamato's entire body... It should be noted that the Observation Device could handle multiple projects simultaneously.
However, doing so would divide its computational resources, slowing down progress on all projects. Usually, he avoided this.
But depending on the situation, adjustments could be made.
The fundamental analysis of Chakra was always ongoing. Adding the Dragon Vein seal analysis and Yamato's body structure modeling... these weren't particularly demanding tasks and could be completed quickly, without significantly hindering the primary Chakra project.
Especially Yamato's body model. If he wasn't studying the differences and principles behind it compared to other bodies, it could be completed in moments.
…
Yamato's body model was quickly generated. Ryuji directly used the 3D Printer to create a living, breathing body.
However, he did not fabricate a corresponding soul.
This was just backup material, created to prevent the cells in the original arm from losing vitality and dying, which would halt further research. It was not intended to be the Wood Release user.
For the actual Wood Release user, he first needed to travel to Konoha, find a suitable candidate, then create a replica of that person to perform a replacement.
Ryuji placed the fresh body into a stasis pod for preservation and continued his research.
He positioned the arm under the Observation Device's sphere for scanning, projecting the body model's structure to examine how this body differed from others.
Yet, after careful observation, he found no structural differences whatsoever.
However.
While there were no structural differences, the cell vitality was exceptionally vigorous, overflowing with life force.
And it was... domineering.
Ryuji extracted a small sample of Yamato's cells and attempted to fuse them with cells from an ordinary person, testing if transplantation was possible. Yamato's cells instantly consumed the ordinary cells.
"So this is Hashirama's cells?" Ryuji fell into deep thought.
'These cells were aggressive and ferocious. If transplanted into a person's body, they would immediately absorb the host's life force as nutrients to strengthen themselves. This phenomenon seemed reminiscent of... the God Tree.'
'Speaking of which, I recall from forum discussions in my past life that Hashirama's Wood Release wasn't merely a simple Kekkei Genkai, but rather a power derived from the God Tree. I wonder if that's true.' Ryuji crossed his arms, his head bowed in contemplation. (A/N: It is, it's written in the official materials)
'This theory was plausible.'
'After all, the God Tree was the Ten-Tails, and also Kaguya.'
'As a descendant of Kaguya, it made sense for Hashirama to manifest the God Tree's power. Moreover, Wood Release and the God Tree's power were identical… both involved plant-based attacks with the ability to suppress and absorb Chakra.'
'If Wood Release power originates from the God Tree... could I use it as a seed to cultivate a new God Tree?'
The sudden idea made Ryuji's heart race.
If he could create a new God Tree, he could bypass all the complicated research and directly reach the 'All Creation' realm by consuming the Chakra Fruit, thereby instantly comprehending and mastering all aspects of Chakra.
But that was just a fleeting fantasy.
He hadn't even fully deciphered Wood Release yet, let alone using it as a seed to grow a God Tree.
No, even if it were truly possible, it would require immense power to secure.
The God Tree caused far too much devastation to a planet. If he tried to plant one here, the Sage of Six Paths would undoubtedly leap out of his coffin to stop him.
So...
'Better to take it step by step. First, I need to fully understand Wood Release.'
Ryuji extracted another sample of Hashirama's cells, then took a small sample from Naruto's blood, attempting to fuse the two.
This time, Hashirama's cells did not absorb Naruto's cells as nutrients. Instead, they seemed to find a home within them… they fused together perfectly, forming a new type of cell.
Ryuji was not surprised by this.
In the final events of the series, Naruto received a right arm made from Hashirama's cells, indicating his body did not reject them.
Next, Ryuji attempted to fuse the new hybrid cells with ordinary human cells.
The two reacted, showing rejection, but no consumption occurred.
'The new cells have become gentler. They no longer possess the instinct or ability to consume other life, but they themselves have become stronger and larger. If a body were constructed from these cells, its vitality would be extraordinary.'
Ryuji pondered briefly, then used the Observation Device to analyze and model the new cells. He wanted to know exactly how strong a body composed of such cells could be.
The results came quickly.
Possessing ten times the stamina of an average person. Ten times the stamina recovery rate. Ten times the life force. Ten times the healing rate... Moreover, as physical training increased the body's strength, these abilities would multiply.
Looking at the data provided by the Observation Device, a single term surfaced in Ryuji's mind: Sage Body.
In the series, the concept of a 'Sage Body' was not explicitly defined; it was a fan-coined term used to describe the physique of certain descendants of the Otsutsuki Clan who possessed extraordinary life force and regenerative abilities, serving as a counterpart to the 'Sage Eye' of the Sharingan.
'Designing a body composed of these cells is simple. The problem is rejection.'
Naturally, developing the Sage Body was for his own use.
But the research had just shown that Sage Body's cells would reject ordinary human cells. Using a soul transfer method into such a body was possible, but the flaws were significant.
A body not originally one's own could never achieve perfect soul-body harmony. Even with a highly compatible vessel, it would only last a few years at most. External injuries would further shorten this lifespan.
'I still need to research a method to fuse Sage cells with ordinary human cells. But before that... I can upgrade Gin's body.'