The next day, during outdoor class.
"Senju Nawaki?"
Hearing this familiar yet somewhat distant name from Hakushi's mouth, Ruri frowned.
"Yeah, before the experimental class yesterday afternoon, I bumped into him. He seems pretty interested in defeating you."
Hakushi watched Ruri's expression with keen interest, trying to see how she would react.
Unfortunately for Hakushi, Ruri only nodded indifferently. Too many people wanted to challenge her; just another Genin from the Senju Clan.
Still, he is the First Hokage's grandson—he must have some skill.
"How strong is he?"
"Probably a little weaker than me."
"Then he's definitely a challenger worth my anticipation."
Knowing Hakushi's full strength, Ruri lowered her estimation of Nawaki's ability. He couldn't possibly defeat her, but he might make things interesting for a bit.
"But I heard from Nawaki-senpai that his teacher is Jonin Orochimaru, who's just returned to the village. Supposedly, he's a once-in-decades genius ninja, so you should be cautious."
"Don't worry. The Jonin who teaches me is a highly respected elder in the Uchiha Clan. Though he's retired, his experience and understanding of Ninja Techniques rival only the Third Hokage in Konoha Village. And besides, I have the Sharingan and your so-called Scientific Training Method. Give me two more years, and I can handle even Jonin."
Ruri spoke confidently.
She was only in fourth grade, with two years left before graduation—more than enough time for her to grow.
Senju Nawaki had connections and resources, but the treatment Ruri received in the Uchiha Clan was hardly inferior.
The Uchiha Clan certainly doesn't lack strong Jonin.
"Just a friendly reminder. I have absolute faith in you. After all, no one knows what might happen to Nawaki-senpai in two years. The war just ended—missions outside are still risky."
Hakushi wasn't cursing Nawaki; it's just that right after the war, things could be even more dangerous. Missions, even with the Sannin watching over you, are still risky.
"Speaking of which, Nawaki-senpai is the First Hokage's grandson. Has he already inherited the First's Wood Style? That was the Kekkeigenkai that pacified the chaos of the Warring States."
Hakushi pondered this.
Hearing Hakushi say that, Ruri replied, "That's impossible. According to our Uchiha Family records, only the First Hokage himself ever awakened Wood Style among the Senju Clan."
Hakushi raised an eyebrow. "That really is strange."
"Strange?"
"Yeah—Wood Style is a Kekkeigenkai, right? Something like that gets passed down to the next generation, just like Uchiha's Sharingan or Hyuga's Byakugan. If Nawaki-senpai hasn't awakened Wood Style, isn't that odd? He's only one generation away from the source of the Wood Style bloodline, his lineage is really close to the First."
"As far as I know, Jonin Tsunade can't use Wood Style either."
Hakushi was even more confused.
Originally he hadn't thought much about it, but upon consideration, it made sense that regular Senju members didn't inherit Wood Style—Hakushi could accept that Wood Style was something Senju Hashirama himself created as a Kekkeigenkai.
In other words, the Wood Style bloodline wouldn't awaken in other members of the Senju Clan, but should definitely show up in his direct descendants.
That Nawaki didn't awaken Wood Style could be chalked up to his age or lack of strength, but Tsunade was already a well-known Jonin, a leader among Jonin.
Such a Jonin still hadn't awakened Wood Style.
Maybe Wood Style isn't even a Kekkeigenkai? Or maybe awakening Wood Style requires something special?
Hakushi couldn't figure it out.
"I remember you once said the First Hokage could use something called Immortal Technique, right?"
"Yeah, I did mention it. It was something I saw by chance in our clan's ancient texts. Supposedly, there's this special energy in nature called 'Natural Energy,' and it seems to be related to Immortal Technique. That's all I know."
"Could this have something to do with Wood Style?"
"Who knows? A lot about the previous generations is hard to verify. Besides, I've never heard of anyone in the Uchiha Clan mastering Immortal Technique. Otherwise, we'd have found a way to pass it down."
Ruri was interested in Immortal Technique as well, but had no idea how to obtain its power.
Compared to something so elusive and intangible, the Sharingan felt much more real to her.
After all, it was the source of power for Uchiha Clan ninja.
"Natural Energy, huh—what is it really like?"
Hakushi looked up at the sky, perplexed, but a spark of curiosity appeared in his eyes.
To understand Immortal Technique, first you have to master Natural Energy, and to grasp Natural Energy, you must find it—and be able to take it in.
Ruri could see Hakushi was very interested in so-called Immortal Technique. It was his problem—whenever he found something unknown, his curiosity outpaced even hers.
"I'll bring you some clan texts about Immortal Technique tomorrow."
"Eh? Are you sure that's okay? Aren't those texts precious?"
"Precious? Hardly. It's just the basics. Just like everyone in the Ninja Realm knows about Wood Style, but only the First Hokage could use it. Same goes for Immortal Technique—knowing it exists is one thing; mastering it is another."
◎
The next day, just as promised, Ruri brought Hakushi some ancient texts about Immortal Technique from within the Uchiha Clan.
They were just collecting dust at her house, totally useless.
Hakushi, though, treated them like treasure.
Even if it was just surface-level info about Immortal Technique, he felt this material was invaluable.
That night, after training with Ruri for a while, Hakushi hurried home, spreading out the Immortal Technique materials on his desk under the lamp.
The scroll recording Immortal Technique was already really worn, dust fused into the surface.
Hakushi didn't mind; he opened the scroll and started to read.
The scroll basically said: starting from ordinary Chakra, you absorb Natural Energy from outside and fuse it, forming what's called Sage Art Chakra.
Create Sage Art Chakra, and you can use Immortal Technique.
To use Immortal Technique, you have to first enter Sage Mode.
The introduction was very brief.
The most important part here was this so-called Natural Energy.
Ordinary Chakra comes from blending one's physical and spiritual energy.
Sage Art Chakra is formed by combining those two with Natural Energy.
And Natural Energy exists in the air and the earth.
In other words, Natural Energy is basically everywhere.
To sense Natural Energy, you need to become one with nature.
The record cuts off here.
How to become one with nature isn't written at all—not a single note.
How to commune with nature, how to sense Natural Energy, how to take it in, how much is proper, what ratio to balance all three energies—none of this is recorded.