"Orochimaru, prepare the experiment immediately. I'm going to retrieve Madara's eyes, and while I'm at it, I'll replace Minato's eyes and bring him back to Konoha."
"Go ahead." Orochimaru didn't even glance at Shin as he began operating on a control panel.
After he entered a password and then an instruction, a cylindrical glass container slowly rose from underground.
"I'll start by giving you a physical examination to record your current data. Once the experiment is complete, I'll record the data again. By comparing the two sets of results, we can calculate the improvement from the experiment and also see which aspects can be further adjusted. As the first subject to undergo this procedure, your experimental data is extremely important to us."
"Do as you see fit." Madara couldn't care less about the experimental process, he only needed to cooperate.
---
Somewhere in the Land of Rain, Nagato was currently hiding in a cave, staring at a wild rabbit sizzling with dripping oil over a fire, swallowing his saliva again and again.
It had been a long time since he'd eaten meat. Today, he was lucky enough to catch a rabbit and could finally treat himself.
"I wonder how Konan and Yahiko are doing. And Minato... he must be even stronger now."
Gazing at the flickering firelight, Nagato recalled the two companions he had once roamed with, and the man who had trained him for half a year, Minato. He couldn't help but sink into memories.
But when he thought about how he might bring disaster to them, his eyes instantly dimmed. He hated it, hated himself for having such ominous eyes. These past two years had been hard for him.
During that time, he had occasionally met other companions, but none were as considerate and trustworthy as Konan and Yahiko, in fact, each was more selfish than the last.
So he parted ways with them one by one, choosing to live alone in the wilderness.
Fortunately, Minato had once taught him diligently for half a year, and in the past two years, he had never stopped training. His strength had steadily grown. Life wasn't easy, but he could manage to survive.
Seeing that the rabbit was nearly done, Nagato took it off the fire and was about to take a bite when suddenly, his hair stood on end. He whipped his head around.
In his field of vision stood a familiar figure, Shin.
Just as he was about to bow in greeting, he noticed something and froze, the rabbit in his hands dropping to the ground unnoticed.
Because he saw a pair of eyes that even he found terrifying, the Rinnegan!
Wasn't that the same as his own eyes? But why did the other person have them too, and the energy radiating from them felt far more intense. He could sense it because his own eyes were not truly his; they had not yet fully awakened, and he could not use the Rinnegan's power freely.
But Shin had already mastered his own eyes to perfection.
"Nagato, long time no see."
"S-Shin... long time no see... you..."
"When you left without saying goodbye, it took me quite a while to find you. I'm here to take you back to Konoha, Minato, Konan, and Yahiko all miss you."
"Konan and Yahiko have already gone to Konoha?" Nagato exclaimed.
Shin nodded. "But before that, I'm going to give you a new pair of eyes."
Nagato was startled at the words, but he said nothing, just nodded slightly. Because he could tell that Shin wasn't discussing it with him; he was simply informing him.
Five minutes later, he opened his eyes again. His surroundings came into focus with perfect clarity.
What surprised him most was the lightness in his body. Chakra flowed far more smoothly within him, and a surging vitality welled up inside, making him feel indescribably comfortable.
"What's going on?" he asked in astonishment.
"The Rinnegan is too powerful, your body couldn't handle it. But from now on, you won't be burdened by those eyes anymore. Let's go, back to Konoha."
Shin didn't explain further; ignorance was sometimes a kind of blessing.
Nagato had already suffered enough in the past, there was no need to give him more troubles to carry.
---
Upon returning to Konoha, Shin handed Nagato over to Minato, instructing him to settle Nagato in and bring over the foster parents who had always worried about him.
After that, he returned to the fourth underground level of the research facility.
"Your eyes." Shin took out two glass containers and tossed them to Madara.
Seeing his own eyes again, Madara felt a wave of nostalgia, as if ages had passed. He didn't waste time, he directly removed the transplanted Sharingan and replaced them with the Rinnegan that originally belonged to him.
The moment they settled into his eye sockets, a torrent of energy erupted, far stronger than when they had been in Nagato's possession.
As expected, nothing compared to one's own. The power was on a completely different level.
Even at his peak, Nagato had been unable to wield the full might of these eyes.
Overwhelmed by their power, he had been forced to split their abilities into six parts, creating the Six Paths of Pain so each could bear a portion of the burden. And even then, he could only use the Rinnegan's basic abilities; as for the unique powers of Madara's Rinnegan, not only could he not use them, he couldn't even sense them.
Once Madara was ready, Orochimaru slowly exhaled, calming his excitement, and tapped the "open" button on the control panel.
The glass door of the cylindrical container slid open.
"Please step in," Orochimaru said, eyes full of anticipation.
Madara strode directly into the cylinder.
Orochimaru pressed a red button. The glass door closed slowly, and the container sank back underground.
Meanwhile, Shin walked to a strange spherical device and placed his hand on it.
In the next instant, vast amounts of yin-yang chakra from his body flowed into the chakra-metal structure and down into the depths.
Inside the glass container, red translucent liquid flowed through a network of pipes, quickly filling the chamber.
Then, as if coming to life, the liquid gathered toward Madara.
Following the method Orochimaru had just taught him, Madara continuously channeled chakra, absorbing the special energy contained in the liquid.
During the process, a tremendous life force also flowed into his body along with the liquid.
The entire process lasted for a full thirty hours.
He remained conscious the whole time, sensing every change in his body, unable to suppress his excitement. He could clearly feel that every cell within him was brimming with vitality.
More than that, the once-weakened cells, on the verge of ceasing division entirely, had begun dividing again.
In other words, the first stage of the immortality research experiment had been a complete success.
Every form of life had various inherent limitations in its genes.
This limitation, Shin called the "genetic lock," affecting every aspect of a being's life functions.
Take cells, for example.
The normal lifespan of each cell is basically fixed. The number of times a cell can divide has long been tightly limited by genes.
Together, these two factors determine the upper limit of a person's life.
The reason Tsunade's first version of the Ninja Art Creation Rebirth - Strength of a Hundred Technique shortens one's life after use is that, while this method appears nearly invincible, able to heal any wound instantly, the price is accelerating the division of one's own cells, thereby indirectly shortening the user's lifespan.
In truth, whether the lifespan of individual cells is shortened, or the frequency of cell division is increased, both will reduce a person's overall life expectancy.
The reason her own lifespan doesn't seem to have been greatly affected is that she enhanced the activity of individual cells, increasing their longevity, which to some extent compensated for the drawback.
Shin and Orochimaru's research into immortality also began from these two angles.
The first approach: Increase the activity of individual cells to extend their lifespan. With the number of divisions unchanged, a longer cell life naturally means a longer overall lifespan.
On this point, the daimyō of the Land of Fire and the Land of Wind could speak from experience, their health had remained excellent in recent years, giving them full confidence in life extension. And with strong confidence comes a greater willingness to invest money.
The second approach: Increase the number of times cells can divide. This is the most difficult, it's like breaking the shackles of genetics and stepping into an entirely new realm.
At this moment, every cell in Madara's body seemed as if it could last forever, and the upper limit of his cells' divisions had also clearly increased.
Even without any formal research background, just a bit of deduction told him that his lifespan would absolutely not be less than two hundred years, in other words, he had at least another 130 years to live.
Sensing the vigorous vitality in Madara's body, Orochimaru's confidence in achieving true immortality grew even stronger.
Five years of research had already extended life by more than a century, to over two hundred years. If they studied for another two hundred years and still couldn't achieve immortality, he and Shin would be useless fools, and would deserve to die.
He now also felt grateful that Shin had stopped him from pursuing his original immortality plan of "Living Corpse Reincarnation."
When it came to which path of immortality to take, Orochimaru and Shin had initially disagreed.
Shin's stance was to work from the genetic level, without replacing the body, to achieve immortality.
Orochimaru, however, believed this to be an impossible task, and advocated body replacement as an alternative form of immortality.
The two debated extensively.
Their final conclusion was:
The advantage of "Living Corpse Reincarnation" is its high feasibility and relative ease of implementation. If Orochimaru truly researched it, his lifespan would indeed increase. The disadvantage, however, is that the side effects are severe.
While body replacement grants a new body, it is impossible for the soul and the new body to be 100% compatible. The resulting rejection inevitably weakens the soul.
Moreover, under the rejection of an incompatible soul, the body itself would deteriorate faster, giving each replaced body a much shorter lifespan than normal, requiring frequent replacement.
While this flaw might be mitigated somewhat with further research, no matter how they argued, they could not make it truly perfect.
Shin's genetics-based approach had the disadvantage of extreme difficulty, it was considered an impossible mission.
But the advantage was also obvious: once this path was successful, the increase in lifespan would come with no side effects, and strength would also be greatly enhanced, a true once-and-for-all solution.
In the end, Shin successfully persuaded Orochimaru.
As the glass container rose again, Madara stepped out slowly, exuding dominance.
He was no longer the withered, aged figure of before, but a vigorous man in his early thirties. His commanding, all-conquering presence made Orochimaru swallow hard.
This was a kind of pure psychological pressure unrelated to strength, just looking at him made it hard to breathe.
"Congratulations, you've surpassed your peak," Shin quickly stepped forward to congratulate him.
Madara laughed. "I haven't danced in a long time. My body's going to rust. How about the two of us find a place to spar?"
"I'm no match for you," Shin waved his hands quickly.
"Don't butter me up. Do you have something more important you need me to do?"
"Nothing gets past you, huh?" Shin spoke, taking out a document and handing it over.
"Remember when I told you that to stop the Ōtsutsuki from invading our territory, we had to master the method of traveling through time and space?"
"This document contains intelligence on an ultra-ancient ruin. It's said that these ruins hold a treasure that can allow a person to travel through time and space. Because I'm worried about unexpected events, we must get our hands on this treasure as soon as possible and start research immediately. So I was thinking we could split up and search in two teams. That way, the chances of finding it will be much greater, and the speed will be much faster."
Madara didn't reply immediately, but began flipping through the document. After reading them through, he said, "Since you won't spar with me, how about we compete to see who can find this thing first?"
"Since you've said it, of course I have no problem with that."
"Don't agree so quickly. If it's a competition, there needs to be a wager," Madara said.
"If I win, you'll fuse the Hashirama cells in my body with Uchiha bloodline cells, so I can reach an even higher level. You didn't need to say it, I'd help you with that anyway."
"You don't get it, do you?" Madara said with a hearty laugh. "What you win for yourself feels far more satisfying."
"Alright, alright, whatever you say."
"Uh..." Orochimaru timidly raised his hand at that moment. "You still need to undergo my physical examination."
"You sure talk a lot," Madara shot Orochimaru a sidelong glance. "Hurry it up, I've got a mission to get to."
---
Half an hour later, Orochimaru had recorded all of Madara's sensations during the experiment, along with his brand-new medical data. While comparing the results using a supercomputer, he backed up the data, classified it as top secret, and archived it.
With everything complete, Shin and Madara set out together.
After completely letting go of his obsession with the Eye of the Moon Plan, Madara had fallen into a brief period of confusion.
But when Shin told him about the Ōtsutsuki clan, and how they would one day seek to destroy the shinobi world, Madara found a new goal.
He was a man who tolerated no rivals; how could he allow others to threaten his domain?
So he had set his sights firmly on the Ōtsutsuki clan, determined to show them exactly what happens when they cause chaos on his turf.
The Ōtsutsuki were strong?
Good. Strength made them worth his planning and effort.
After parting ways with Shin, he traveled southeast through the Land of Fire, eventually reaching the coastline, one of the locations where Konoha's archaeological teams were working.
Archaeology, a practice that might seem out of place in the shinobi world, had actually been carried out for many years.
Its main purpose was to study material remains from ancient human activity, in order to understand and control human life, transform nature, and serve fields like agriculture, industry, and medicine.
The shinobi world had long engaged in archaeology because excavations of ancient ruins had indeed brought tangible benefits to the great villages.
On a small scale, artifacts like the few divine tools Itachi later carried, the weapons Orochimaru discovered, and the Six Paths blades had all been unearthed through archaeology.
On a larger scale, the reason the shinobi world's "technology tree" was so crooked, with sudden bursts of technological progress in strange areas, was due to archaeological finds.
In other words, many discoveries in archaeology had directly driven technological advancement in the shinobi world.
Even the invention of many ninjutsu techniques had been inspired by archaeological work.
The names of techniques like Tsukuyomi, Izanagi, and Amaterasu had their origins in names of deities recorded at ancient divine ruins found through archaeology.
Shin and Orochimaru had touched upon taboos because they had researched certain ancient relics.
Orochimaru had even conceived his Living Corpse Reincarnation technique after seeing a method of "soul descent" recorded in one such ancient ruin.
Nowadays, Konoha's archaeological team was formed personally by Orochimaru, aimed at finding certain things he and Shin desired.
Several years ago, Shin had told them about the ultra-ancient ruins and instructed them to keep watch during excavations, sending any intelligence back to Konoha immediately.
The team hadn't disappointed, they had preliminarily identified several possible locations where the ultra-ancient ruins might be.
But these were only general areas. Actually finding the ruins would still be no easy task.
Standing before the vast, endless ocean, Madara, who had been kept alive for decades only by the Demonic Statue of the Outer Path and hadn't moved freely in years, felt his blood surge like the crashing waves, his heart brimming with boundless ambition.
However, he didn't join the archaeological team currently surveying the site.
He had already read the latest intel they'd sent back, so there was no need to ask again. Instead, he found a deserted spot and plunged straight into the sea.
In the depths, Madara piloted a deep-sea exploration device given to him by Shin, moving swiftly along the ocean floor and investigating every place he passed.
The device resembled a shark, with a perfectly streamlined body and special coating that greatly reduced drag, vastly increasing swimming speed.
Inside was a cockpit just big enough for one person to operate.
At the front of the cockpit was a large display made of nine split screens, each with its own function.
Before the screens sat a comfortable leather chair, the pilot's seat, with a control stick on each side.
Much of the cockpit's interior was forged from chakra metal, while the outer shell was made of an extremely hard metal, with only a few viewing ports fitted with thick, ultra-pressure-resistant glass.
The shark's eyes were two powerful searchlights.
Its mouth housed a device that could detect spatial fluctuations, scanning every ten seconds. If anything suspicious was detected, the screens inside would issue an alert.