Nighttime. In his base, Orochimaru was deep in thought, 'Had I been completely betrayed?'
He had tried summoning Manda these past few days, but there wasn't even a hint of a response.
Just then, a voice sounded from outside the door. "Orochimaru-sama, I'm here."
"Setsuna-kun, please come in."
Orochimaru examined the visitor, "The Chunin Exams seem to be starting soon, don't they? Do you still have time to visit me, Setsuna-kun? Shouldn't you be preparing more for yourself?"
Setsuna said calmly, "It's just the Chunin Exams. Nothing much to prepare for."
"Heh, with Setsuna-kun's strength, of course the Chunin Exams are nothing to worry about. But what about the potential incidents that might occur during the exams?" Orochimaru said with a sinister tone. "Holding a joint Chunin Exam at such a sensitive time makes it hard not to suspect Sunagakure's intentions."
"I'm just a lowly Genin. Matters like that aren't for me to consider," Setsuna said modestly.
"A lowly Genin, is it?" Orochimaru couldn't help but laugh. "By the way, Setsuna-kun, have you summoned Manda recently?"
"No," Setsuna answered very frankly. He had summoned Manda a year ago, so it certainly wasn't recently.
"Is that so? Snake summoning creatures really are unreliable," Orochimaru sighed, seeing that Setsuna didn't seem to be lying.
Setsuna's eyes flickered, "Speaking of snake summoning creatures, Orochimaru-sama, I heard from Minato-senpai that Mount Myoboku has Senjutsu Inheritance. Does Ryuchi Cave have it?"
Although Minato hadn't actually said that, it didn't matter. He just needed to serve as a good background character.
"Oh? Is Setsuna-kun interested in Senjutsu?" Orochimaru asked.
"Just a bit curious," Setsuna answered truthfully.
He wasn't actually interested in the Senjutsu themselves, but rather the various enhancements brought by Sage Mode.
"Practicing Senjutsu is very dangerous. If you are devoured by Natural Energy, you become one with nature," Orochimaru sighed. Even Jiraiya could learn Senjutsu, but he himself lacked the aptitude.
In his view, this was entirely because his mind was too restless, going against the 'stillness' required for practicing Senjutsu.
Jiraiya, on the other hand, although usually hyperactive, could actually calm his mind when practicing Senjutsu.
"Natural Energy?" Setsuna recalled what Don Slime had said. "Does only Natural Energy exist in nature? Could there be Chakra as well?"
Orochimaru looked at Setsuna with some surprise, then narrowed his eyes and asked, "Why would you think that? The Academy should have taught you long ago that Chakra is refined from physical and mental energy."
"Because I came into contact with Kumogakure's Eight-Tails' Jinchuriki last time and found it puzzling. In rumors, Tailed Beasts seem to be the physical embodiment of Chakra. But if they can't refine Chakra, then logically, every time a Jinchuriki borrows their power, they should be weakened. But that's not the case at all. So I suspect their Chakra gets replenished from nature."
"Ninja willing to think like Setsuna-kun are becoming increasingly rare," Orochimaru said with some emotion, his expression turning serious, "To answer this question, we must first clarify one thing, Setsuna-kun. Do you think the Chakra used by a Ninja for a Jutsu, or the Chakra of a person after they die, remains in the Ninja World?"
Setsuna answered seriously, "I wouldn't say absolutely, but at least a portion does."
In his view, so-called Chakra was data carrying personal information, similar to the Otsutsuki Clan's [Kama].
The Otsutsuki Clan's [Kama] involved digitizing themselves, then copying and implanting it into others. When the vessel's body was completely replaced by the Otsutsuki's data, the Otsutsuki would be resurrected.
The Chakra of Asura and Indra remained in the Ninja World, constantly reincarnating. Their Chakra might not reach the level of the Otsutsuki, but it was very close.
Also, after Kato Dan's Edo Tensei was released, he could transfer his Chakra to Tsunade. Obito, after death, could still give his eye to Kakashi. These instances seemed to indicate that Chakra doesn't simply dissipate after death but can continue to be transferred.
Orochimaru said, "You know about plastic, that product of technology, right? This synthetic material is difficult to degrade in nature. Chakra is the same. As a secondary energy synthesized from physical and mental energy, it takes a long time to decompose. The Chakra of more powerful Ninja is even harder to decompose."
"For nature, of course, the sooner Chakra decomposes, the better. But the Ninja World just happens to have creatures like the Tailed Beasts. They constantly absorb Chakra and use Chakra, causing Chakra to accumulate continuously in the Ninja World, and these Tailed Beasts grow stronger and stronger."
Setsuna was inwardly startled, 'That seemed true. The Nine-Tails in its juvenile form was vastly different from its current appearance. Especially the Seven-Tails, Chomei, which transformed from a juvenile pupa into a flying beetle.'
'The Tailed Beasts, as aggregates of Chakra, growing meant they were constantly absorbing Chakra, didn't it?'
'Could it be that the Sage of Six Paths created the Tailed Beasts to have them purify Chakra? To prevent Chakra from being degraded?'
Setsuna couldn't help but think this. After all, the Sage of Six Paths' claim that he 'created the Tailed Beasts to make them believe in and help humans' was utterly unconvincing.
For a thousand years, the Tailed Beasts had been seen as symbols of disaster and had never coexisted peacefully with humans. Meanwhile, the Sage of Six Paths just watched the whole time?
Also, during the final battle, the Sage of Six Paths summoned the Kage from various villages. There should have been nearly a thousand years of powerful individuals before the First Kage, yet the Sage of Six Paths didn't summon them.
Now it seemed perhaps the Chakra left behind by those powerful individuals had been 'washed' by the Tailed Beasts, no longer carrying their personal information.
"As expected of Orochimaru-sama. While everyone else is fighting for power and profit, you are already exploring the essence of the Ninja World," Setsuna praised sincerely.
"Heh, I only discovered the nature of infinite Chakra while researching the Second Hokage's Edo Tensei," Orochimaru, having his itch scratched, as this was indeed his proudest achievement, couldn't help but feel a bit smug, despite his usual temperament.
"Edo Tensei?" Setsuna raised an eyebrow, 'Was this something to be said so openly?'
Orochimaru was inwardly startled, 'I actually got carried away and slipped up.'
'Should I silence him?' A murderous glint flashed in Orochimaru's eyes, but then he remembered the battle reports he'd heard about Setsuna, 'Forget it, I probably can't win.'
"Cough, I researched this Jutsu for Konoha's victory. Anyway... um, let's return to the original topic. Precisely because Natural Energy contains more and more Chakra impurities, separating and absorbing pure Natural Energy has become increasingly difficult. So this first step is extremely dangerous. If you aren't absolutely certain, I advise you not to attempt it."
Setsuna thought thoughtfully, "I heard from Minato-senpai that Senjutsu Chakra is a 1:1:1 mixture of Natural Energy, physical energy, and mental energy. Since Natural Energy is mixed with Chakra, is it possible to directly alter the ratio and refine it while absorbing Natural Energy?"
"Theoretically, yes. But aside from the Tailed Beasts, it's impossible for anyone to do it," Orochimaru scoffed and shook his head. "Absorbing pure Natural Energy is dangerous enough. If you absorb impure Natural Energy, you would be instantly backlashed by the Natural Energy."
"I understand," Setsuna nodded, then said inwardly, 'Don Slime, my dear friend, the heavy responsibility of refining Senjutsu Chakra for me from now on rests on you.'
Don Slime was speechless. "Who do you think I am? Your hired help?"
"Ah? I thought for a Cosmic Emperor, this should be an easy task. It's fine if you can't do it. After all, you're not from this universe..." Setsuna sighed.
Don Slime slammed the table (metaphorically) and stood up. "Let me state clearly, I'm not falling for your provocation. It's just that you're right, this kind of thing is indeed very easy for me, a Cosmic Emperor. I'm just bestowing a bit of my power upon you."
Setsuna praised sincerely, "As expected of the Cosmic Emperor, Don Slime-sama. So magnanimous."