"Furthermore," Shinno continued, "not only does this forced-growth body have its own hidden problems, but to prevent any soul incompatibility during the transfer, you can't even allow the clone to develop a soul. Its consciousness must be erased as it grows, turning it into a living husk, a vegetable."
"That way, when you use the Living Corpse Reincarnation to possess a shell that shares your own cells, there are no issues. The compatibility problem is solved, and because there's only one soul in the body—yours—the side effects vanish."
"If you don't believe me, you can use me as an experiment. First, clone a body for me. After I use the Living Corpse Reincarnation, you can observe it for yourself. A rapidly grown body like that will only last a few months. But the kind of perfectly cultivated body I developed can be used for over a decade. The drawback, as I told you, is the time it takes. It needs to be nurtured at a human pace, for nearly eighteen years."
"But I can guarantee it has no side effects..."
Shinno rattled on, but the bottom line was simple: bringing him back to life would be useful. He could help Uchiha Nagi achieve longevity.
It was no wonder that Orochimaru later sent Sasuke to find him in search of the complete version of the Living Corpse Reincarnation. The version he had given Orochimaru was the first draft, riddled with flaws, much like the Second Hokage's original Edo Tensei. Orochimaru had improved both of them himself over time.
After a moment of consideration, Nagi looked at Shinno seriously. "I'll consider it. If what you say is true, I can clone a rapidly grown body for you and then let you go. You have my word."
Shinno breathed a sigh of relief. After all, who would choose death if they had a chance to live?
"However, before that, you have to stay and work for me."
"I can do that..."
Seeing Shinno agree, Nagi said no more. Agreeing was one thing, but feeding the ultimate summoning beast was another. He plunged the kunai into Shinno's head, erasing his consciousness.
He tossed the now-unconscious Shinno to the ultimate summoning beast.
It seemed the creature had learned its lesson. If it swallowed him in one gulp, the meal would be over. But if it ate him piece by piece, it could eat its fill. This time, the ultimate summoning beast grabbed Shinno and took a bite, tearing off half his body...
When Shinno's reanimated body regenerated, the beast took another bite. And then... another.
Uchiha Nagi was playing the Edo Tensei's bug for all it was worth.
An hour later—
"So it's not truly infinite chakra after all..." Nagi mused, jotting down data in his notebook.
Within the hour, Shinno's reanimated body had regenerated countless times, but the process was getting progressively slower. It went from regenerating in a single second to taking ten, and now, a full thirty seconds for his body to reassemble.
Finally, the ultimate summoning beast lost its patience and swallowed Shinno's reanimated body whole.
Under Nagi's careful observation, the beast's chakra surged to a certain point, and the reanimated body within it completely lost its energy, unable to regenerate any further.
"Damn it. So much for infinite chakra. It seems it has its limits," Nagi said, shaking his head. The Edo Tensei bug in this world wasn't a completely foolproof exploit.
The "infinite chakra" of the Edo Tensei was merely a system that rapidly gathered the energy a dead person expended and redirected it back into their reanimated form. If that energy wasn't just expended but directly absorbed, as the ultimate summoning beast had done, then the reanimated individual's chakra source would be depleted.
Without infinite chakra, there could be no infinite regeneration.
Furthermore, by analyzing the data from each time Asuma's and Shinno's bodies regenerated, Nagi discovered something else. Even if their chakra wasn't being drained, a minuscule fraction of energy was consumed with each revival. Eventually, after enough deaths and rebirths, the reanimated body would lose all its energy and return to being just a corpse.
To put it plainly, the Edo Tensei allowed a body to be reassembled many times, but not without a price. The more times it was killed and revived, the slower the regeneration would become, until finally, it was dust to dust, earth to earth.
Happiness had come so suddenly. Just a short while ago, Nagi had been stressing out, stalling the messengers from Kirigakure who were demanding he return the Three-Tails. He was afraid that without the Tailed Beast, his Sky Fortress would become a useless pile of scrap iron. But now, he had two potential replacements.
The ultimate summoning beast could be fed reanimated shinobi and used as a nuclear battery to power the Sky Fortress. The Zero-Tails could do the same, but it seemed to have greater potential as a jinchuriki. Nagi hadn't yet decided whether to seal it into Amaru.
"Still, the chakra from Asuma and Shinno is far too little. It's not enough to power the entire Sky Fortress..." Nagi frowned, running through the possibilities. No matter how he looked at it, his mind kept returning to one man: the First Hokage, the legend with chakra by the ton.
If he could just get his hands on him, he could power the fortress indefinitely. And he didn't even need him to be conscious or to fight; he just needed him in the core, supplying the dead man's chakra.
But he knew with absolute certainty that Orochimaru would never give up the First and Second Hokage. The snake Sannin was eagerly awaiting his showdown of the year: student against teacher, with himself fighting the Third Hokage, and the Third fighting the First and Second...
"Besides them, who else has that kind of monstrous chakra?" Nagi frowned, thinking hard.
Images of the first few generations of Kage from the great ninja villages flashed through his mind. From what he remembered from his past life, the First Kage were at the peak of power in the ninja world, capable of reshaping the landscape. The Second Kage were a step below but still often a one-man army.
But starting from the Third Kage...
In the entire ninja world, it seemed the weakest of the Thirds was Konoha's. Just look at the Third Raikage, or the Third Tsuchikage, Onoki. Sarutobi Hiruzen was laughably weak in comparison.
"Alright, I'll go after them..."
Who to go after? The First and Second Kage, of course. Before Yakushi Kabuto came along, none of the great villages were particularly on guard when it came to their ancestral tombs. They had been buried for so many years, their bodies reduced to bones, that everyone assumed there was no intelligence to be gained from the corpses. Security was basically nonexistent.
For Nagi to go grave-robbing before Kabuto did was a total scumbag move. Even if the reanimated shinobi he acquired weren't used as chakra batteries for the Zero-Tails, they would make excellent fighters.
After careful consideration, Nagi concluded that the reason the future Kabuto didn't reanimate the First Kage from the various villages was probably that he couldn't get to their remains. Most of his reanimations started from the Third Kage generation. And among all the Thirds, the most powerful was the Raikage.
"I choose you, Third Raikage..."
Nagi was also curious to see what kind of man was so tough he could fight ten thousand ninja for days and nights on end, dying not from his injuries, but from sheer exhaustion.
Besides, he still hadn't finished copying the Lightning Release Chakra Mode. The jutsu was proving more complex to copy than he had anticipated, and there were many parts he still didn't fully understand.