Nagato had neither the time nor the desire to visit Mount Myoboku or Ryūchi Cave.
Compared with the sages of those two places, Sage Katsuyu was already the most mild-tempered. And now that she'd been warned by his 600 Billion Paper Bombs, she shouldn't deliberately make things difficult for him or give him different treatment. So Nagato trusted Katsuyu and felt Shikkotsu Forest was already his best choice.
He wouldn't even consider Mount Myoboku. It was an enemy faction. Ryūchi Cave was even worse, since it belonged to the evil and chaotic faction. The White Snake Sage taught Senjutsu by injecting Natural Energy into practitioners with her fangs. No one could know how much she injected or whether it contained any germs. The funniest part was that the White Snake Sage was always ready to eat anyone who failed to master it.
It was ridiculous. What sane person would trust a snake that planned to eat them?
Learning Senjutsu in a place like that, and putting his life in the White Snake Sage's hands, was out of the question for Nagato. So he couldn't accept Katsuyu's offer.
"Are you really that worried Konan will blow up your lousy forest?" Nagato spoke through Shurado, his tone scornful. He thought Katsuyu was being incredibly petty. Was she really a shut-in bug?
"Easy for you to say. It's not your home. How could you possibly understand?" the little Katsuyu cried indignantly in an adorable voice.
Just looking at her now, she was soft, cute, and lovable. But who would have guessed that this mild-mannered giant slug's Senjutsu training method was so terrifying?
"Actually, you could look at it this way: even if I died, maybe Konan wouldn't blow up your forest?" Nagato ventured.
"This sage can use Senjutsu! Senjutsu! Do you think I can't sense how determined your companion is to protect you?" Sage Katsuyu had already confirmed it. When Konan had followed Nagato's order and revealed the 600 Billion Paper Bombs, she'd genuinely been prepared to blow up Shikkotsu Forest. Otherwise, why would Katsuyu have been so nervous?
"Oh, so you can tell? Then that's a relief..." Shurado nodded. "I was worried you might still be clinging to wishful thinking."
Konan was unquestionably a reliable companion, someone he could trust to watch his back. Nagato was certain of that.
"You..." Katsuyu was at a loss for words. After all that, had he only wanted to confirm this?
"Don't bother trying to talk me out of it. I'll be blunt: my goal is to become a true god. If I can't even learn the Senjutsu here, then dying sooner rather than later isn't something I can't accept."
He'd had enough of an ordinary life in his previous world. Now that he'd finally gotten another chance, how could he live in fear? Nagato figured that, as a transmigrator, he'd already died once. Dying again wouldn't be a big deal.
Dying on the path to becoming the strongest was better than living a mediocre life.
"You..."
Perhaps she'd been moved by the force of Nagato's resolve as it surged from the depths of his heart. Katsuyu sounded helpless.
"Still, even if I die, I want to know exactly why." Shurado continued, "You said no one had ever learned your Senjutsu. Was that because no one from the Ōtsutsuki Clan had ever come here?"
"You know about the Ōtsutsuki Clan?" Katsuyu asked in surprise, as if she hadn't expected Nagato to be so well-informed. "But the truth isn't what you think. Well, since you're so brave, I'll tell you. These days, when people talk about the Ōtsutsuki Clan, they mostly mean Hagoromo Ōtsutsuki's branch. Hagoromo's descendants are divided by their talents into those who inherit the Sage Eye and those who inherit the Sage Body. Those who inherit the Sage Eye don't have the immense Chakra reserves required to learn Senjutsu. Those who inherit the Sage Body don't meet the Chakra requirements until they're close to maturity. Once they reach that stage, their Sage Body senses Natural Energy on its own and they learn Senjutsu automatically. They don't need to go elsewhere to study it."
Nagato thought it over, then had Shurado speak again. "So any mature Sage Body can learn Shikkotsu Forest's Senjutsu?"
"No." Katsuyu immediately rejected the idea. "A mature Sage Body senses, absorbs, and uses Natural Energy on its own. The energy in the Black Pool can no longer affect them, so they can't learn Shikkotsu Forest's Senjutsu."
"What do you mean?"
"You don't need to know all that. Well, you can understand it this way: the Senjutsu of each sacred place is equivalent to the Chakra unique to that place. Learning that place's Senjutsu is a process of being affected by its unique Chakra. A mature Sage Body already has its own Senjutsu Chakra, so it isn't affected by a sacred place's Senjutsu. For example, the acid in Shikkotsu Forest's Black Pool is a special kind of acid found only in my body. Natural Energy can neutralize it. A mature Sage Body wouldn't be affected at all by entering the Black Pool."
Nagato immediately thought of how the Preta Path had resisted the Natural Energy inside Naruto when he'd controlled it earlier. Still, he had Shurado argue back. "What about Mount Myoboku? Naruto learned its Senjutsu. And what about Ryūchi Cave?"
Katsuyu fell silent for a while, then suddenly asked, "Are you really planning to learn Shikkotsu Forest's Senjutsu?"
Nagato felt like scratching his head. Why was this giant bug asking him that again? He could only answer through Shurado. "Yes!"
"Even though you know you might die?"
Nagato frowned. He thought the bug was crazy.
"Yes!"
Katsuyu fell silent again for a while. "Fine. You're doomed anyway! I'll tell you: the methods used at Mount Myoboku and Ryūchi Cave are nothing more than half-baked practices by the younger generation."
"What do you mean?" Shurado immediately asked.
"I mean that those methods can't reach the advanced stages of Senjutsu. They can barely even reach the intermediate stage."
"Senjutsu has different levels?!"
"Heh." Katsuyu scoffed and said nothing.
Nagato couldn't help rubbing his forehead. He felt a little dizzy. As a transmigrator, he'd always been most proud of how much he knew about this world, but it seemed there were far too many unsolved mysteries in Naruto.
"So you're not going to tell me the levels of Senjutsu?" Shurado sounded exasperated. "Then at least tell me what it takes to train in Shikkotsu Forest's Senjutsu."
When Tsunade learned how difficult it was to train in Shikkotsu Forest's Senjutsu, she immediately gave up. She knew a great deal about acid, but even she didn't know the specific requirements, so Nagato couldn't find out from her.
Katsuyu's four feelers twitched. "Of course I'll tell you. It looks like you've already made up your mind to become the heir to my Senjutsu. You're practically my child now."
Nagato's mouth twitched. He really couldn't understand how this bug's mind worked.
Katsuyu spoke seriously. "At first glance, you seem quite suited to my Senjutsu. Unfortunately, you're actually unqualified in every way. If you really entered the Black Pool, you'd probably be reduced to bones in seconds. First, humans who want to learn Shikkotsu Forest's Senjutsu need Chakra reserves approaching those of a Sage Body. Second, they need strong, but not excessively strong, Chakra control, as well as the ability to resist Wraiths."
Nagato straightened his back and had Shurado speak. "You might not believe me, but I actually have a Sage Body."
Katsuyu: ...
Nagato seemed to hear Katsuyu laughing at him.
"Mm, that's a good joke. After you die, I'll try to remember it for a long time," Katsuyu said, sounding like she was holding back laughter.
"What do you mean? I really do have a Sage Body."
"With that little Chakra?" Katsuyu could barely keep the amusement out of her voice.
"Th-that little?" Nagato was stunned. His Chakra reserves were already enormous, weren't they? He'd blown up all of Konoha without even feeling low on Chakra. But then he remembered how much Chakra Hashirama Senju, a Sage Body, had. EMMMM... Fine, there did seem to be a bit of a gap.
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