Senjutsu

Three days had passed since Takara captured Utakata and extracted the Six-Tails, spending almost all his time learning Sage Mode from Katsuyu in the hope of mastering it before reaching Takigakure, where he wanted to carry out an experiment.

Using a special slime secreted by Katsuyu herself, Takara felt the natural energy for the first time, and before he could properly scrutinize it, he encountered an unexpected change that even surprised the wise slug.

"Are you saying that the Ryumyaku inside me is absorbing the natural energy I'm gathering?" Takara repeated when Katsuyu understood the problem and told him. "So, will I not be able to use Sage Mode?"

That would infinitely complicate his plans.

"I should have thought of that earlier; the Ryumyaku is essentially a chakra vein that runs through the planet and is attuned to the natural energy of the planet itself," Katsuyu said, shifting from left to right as she spoke. "With the fragment your mother sealed inside you, the adaptation your body went through, and now that you've come into contact with natural energy... hmm, it's complicated, a little complicated. Oh, but don't worry, it doesn't mean you can't use Sage Mode; we'll just have to tweak how you use it a bit."

Takara breathed a sigh of relief; as long as he could learn Sage Mode, that's good.

Correctly, not like Jiraiya's defective version.

"What should I do then?" Takara deferred to Katsuyu as the expert in this matter.

Katsuyu didn't respond immediately but pondered for a long while.

Sage Mode required a special state, but Takara's condition completely altered the standards, requiring equivalents to avoid long-term issues.

"How much natural energy does the Ryumyaku take when you absorb it?" Katsuyu asked.

Takara sensed it for a moment, silently calculating.

"About two-thirds," it wasn't even a half and half; the Ryumyaku was a bit greedier for natural energy.

"Hmm," Katsuyu lowered her gaze and then raised it again to look at him. "Try to absorb more; let's see if there's an upper limit or if any changes occur."

She herself climbed onto Takara's back, ready to take in the natural energy that might overflow in case of saturation.

Takara didn't start absorbing natural energy like crazy but maintained a steady intake within his measure, attentive to any signs.

Practicing the Shikkotsu Forest Sage Mode and failing wouldn't turn him into stone like in the case of the toads; instead, it would completely melt the practitioner, reducing them to a puddle of themselves that would burn the ground with its acidity until evaporating and disappearing completely.

It wasn't a fate Takara was enthusiastic about, so even if it took him a bit longer, his life was a priority.

Thirty minutes later...

"Stop!" Katsuyu shouted.

Takara immediately ceased absorbing natural energy and quickly tried to see if any part of him was liquefying, but feeling no issues, he was puzzled.

"I think I understand your situation now," Katsuyu dismounted from his back and turned around to face him. "While the process is a bit different, you should be able to enter Sage Mode now."

"Huh?" Takara didn't even feel like he had natural energy interacting with his chakra—and he'd only been practicing for a few days.

"Entering Sage Mode and knowing how to use it are two completely different concepts, not to mention that your situation is somewhat unique," Katsuyu pointed out. "Plus, you don't have to feel your own chakra; you feel the Ryumyaku fragment."

Takara did just that and was left dumbfounded.

"What the hell just happened?"

The Ryumyaku seemed to be slowly but steadily spitting out the natural energy it had consumed, generating a third type of energy with purple hues and dark green accents.

"That's senjutsu chakra, and when you circulate it through your chakra coils, you'll enter Sage Mode," Katsuyu explained excitedly. "Plus, it's a significantly more potent version than what a human could produce, given how this blend originates."

"But I'm not doing anything, and it's still increasing?" Takara asked, a bit disconnected.

"While other human practitioners need to constantly refine natural energy to generate senjutsu chakra and maintain their Sage Mode, it seems that you can absorb natural energy in advance so that the Ryumyaku swallows it and returns it to you in the form of senjutsu chakra," Katsuyu outlined technically. "The advantage of this method is that you don't need to worry about absorbing too much natural energy that your body can't handle, and you have the ability to store the senjutsu chakra if you don't use it."

"And the disadvantage?"

There's always a downside in these kinds of situations, and Takara would be foolish to think everything is in his favor.

"You'll need some kind of seal to contain the senjutsu chakra when it reaches a certain amount and you don't need to use it, to avoid feeling uncomfortable and to have better control until you get used to it," Katsuyu admitted without holding back. "Tsunade-sama had a similar seal to store chakra on her forehead."

"Hundred Strength Seal?" Takara knew about the seal.

Like many others, he initially thought its purpose was to store some chakra to maintain Tsunade's youthful appearance and satisfy her vanity. Only later did it prove how terrible it was once it released all the accumulated chakra over the years to use it during the great fight.

"Do you know about the seal?" Katsuyu wasn't surprised; it was one of the techniques that thousands of kunoichis envied Tsunade for. "You just need to do something similar, but focused on senjutsu chakra. With your knowledge of fuinjutsu and my help, it shouldn't be complicated."

At most, it would take them a month if they didn't encounter serious obstacles.

"This might be abrupt, but do you happen to know the technique?" Takara tentatively inquired, hoping to have a reference to work with.

"I... know a little."

In fact, Katsuyu knew about the technique because of Tsunade and was hesitant to give it up so that her contractor could use it. It's just that Tsunade emphasized the importance of chakra control to successfully practice it, and she wasn't sure if Takara would meet the high requirement.

The technique itself even dates back to the time of the Sage of the Six Paths!

A fuinjutsu said to be the pinnacle of chakra control.

And upon reflection, she wasn't doing anything wrong. Tsunade died, and the technique could actually be considered lost if she didn't pass it on at some point.

It could be a way to preserve the legacy; surely Tsunade would be happy to be remembered through Takara. Plus, with the mask, no one would notice the seal on his forehead.

Thus, Katsuyu shared the technique, and with it as a reference, they both successfully created the seal to store the senjutsu chakra, taking the form of a purple hourglass with dark green accents.

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Are there any ATLA fans out there?

Well, just so you know, I started an ATLA FF today, on my Patreon.

This one will be exclusive to there, as a reward for the support of many.

As for the remaining three Naruto ones (one per village), those will come out as usual, in advance on Patreon and then there, so nobody panic.