Kimura Takuya went to the hospital in the end.
He hadn't been taken there by Ino. After the exam, he'd gotten his Forehead Protector and gone on his own.
After agreeing on a time to study together with Neji,
Ino had wanted to ask Takuya out to eat, but she had work at the hospital that evening, so they had to call it off.
A worker's soul was a worker's soul. Even after transmigrating into the Ninja World, he was still a worker.
And so, the worker arrived at Konoha Hospital.
"Tomiko, what's for dinner tonight?"
"Takuya, it's ramen tonight. I've already saved you a portion."
Kimura Takuya happily sat down and dug in.
Seeing the Forehead Protector on his head, Tomiko smiled and teased him.
"Ha, who'd have thought the little brat had grown up? You've become a Genin who can stand on your own, and you're starting work at the hospital as soon as you graduate. Don't you find it boring?"
Tomiko looked radiant in her nurse's uniform. She was a pleasure to behold.
But Kimura Takuya didn't look at her much. He just focused on eating his ramen.
"How could I? I'm a veteran employee too. I started working at the hospital the same day you did. Don't you remember?"
"Haha, I did come here as soon as I graduated. That's why I asked if you'd find it boring."
"It's not boring. I quite like Medical Ninjutsu."
"Speaking of which, with your talent for Medical Ninjutsu, even if the director took you on as her student, no one would object. It's a pity she's been away for years. Who knows when she'll come back?"
Tsunade, huh? The founder of Konoha Hospital and the pioneer of Medical Ninjutsu in Konoha.
The strongest medical ninja and one of the famed Konoha Sannin.
At the moment, Tsunade was still wandering the world to avoid her debts.
Learning Medical Ninjutsu from Tsunade wasn't going to be easy.
Whether she'd even agree to teach him was another matter. Just finding her would be difficult enough.
He might as well use that time to train on his own. Besides, Kimura Takuya's goal was never to become a medical ninja.
He was learning Medical Ninjutsu only to disguise his Immortality.
After dinner, Kimura Takuya went to make his rounds through the hospital wards.
Medical ninjutsu wasn't a cure-all. It could treat external injuries, but it wasn't much use against other kinds of illnesses.
In a sense, Medical Ninjutsu had been invented for war, not for treating the sick.
When ninjas fought, most of their injuries were external.
That was why Medical Ninjutsu had been developed to speed up metabolism and promote cell division, allowing wounds to heal quickly.
The world's other medical knowledge—the knowledge needed to treat illness and save lives—was sorely lacking.
In truth, its medical standards were no better than those of Japan's Warring States period.
The technology in Naruto was bizarre, too. They had radios, electric lights, televisions, and refrigerators, yet when a fight broke out, magic-wielding warriors armed with cold weapons took the field. There were no firearms.
And yet they had "Iron Man" and had even developed laser weapons.
They also had Mecha Naruto and Mecha Kurama. It was ridiculous.
Over the years, Kimura Takuya had filled in a lot of gaps in his basic medical knowledge.
Otherwise, why would he have been recommended for the Ninja Academy and assigned a hospital job upon graduation?
Just learning Medical Ninjutsu would only have gotten him a job as a male nurse.
Now that Kimura Takuya had officially joined Konoha Hospital, he'd started out as a physician's assistant.
Normally, after a few years, once he had enough chakra, he could become a full-fledged physician.
Though his chakra was already sufficient, as he'd said, his goal wasn't to become a medical ninja.
After finishing his rounds, Kimura Takuya went to the hospital laboratory.
There was no one around at night, and he often came here to conduct research. The acting director had given him a key as a special favor.
Tonight's work was about to begin.
He dissected a frog—not a Toad from Mount Myōboku.
It was just one he'd caught while passing through a grassy area.
Over the years, he'd dissected nearly every small animal in Konoha.
At first, he'd just been bored and wanted to see how the creatures of the Ninja World differed from those in his previous life.
He hadn't known until he started dissecting them, and what he found was startling.
The creatures of the Ninja World were generally much stronger than those in his previous life.
That included humans.
This discovery led him to realize that chakra might affect everything. Of course, it was even more likely that Natural Energy was responsible.
Natural Energy was a mysterious force that permeated the entire Ninja World.
Mixed with chakra in a specific proportion, it became Senjutsu Chakra.
By mastering Senjutsu Chakra, one could enter Sage Mode, and even ordinary ninjutsu became senjutsu.
Senjutsu was more powerful and more destructive than ordinary ninjutsu.
It made sense. The energy being used was stronger, so the techniques released with it would naturally be stronger too.
However, ordinary methods couldn't detect Natural Energy. Even the Byakugan couldn't see it.
But by comparing his dissection experiments, Kimura Takuya had come up with a few ideas.
It seemed that Natural Energy subtly affected the bodies of animals.
The longer they lived, the more pronounced the effects became.
And after dissecting thousands of animals of all kinds, he'd discovered something interesting.
Kimura Takuya found that frogs, loaches, and Katsuyu were the three animals most noticeably affected by Natural Energy.
Now that was interesting.
Anyone who'd watched Naruto knew about the Three Great Sage Regions.
And didn't they correspond precisely to these three creatures?
So did that mean Ryūchi Cave was actually full of loaches instead of snakes?
Or did the White Snake Sage have loach ancestry?
Setting aside the question of the White Snake Sage's ancestry for now, he considered why these creatures had been chosen.
After closely examining what they had in common, Tuoye realized that they could all breathe through their skin.
That's right.
Being able to breathe through their skin meant that their cells could come into direct contact with the air and exchange oxygen and energy.
That meant Natural Energy in the air might accumulate throughout their cells.
Senjutsu Chakra was a combination of spiritual energy, cellular energy, and Natural Energy.
When the three sages refined chakra and drew upon their cellular energy,
they might also be drawing upon the Natural Energy accumulated in their cells.
That could be what allowed the three forces to merge into a new kind of energy—Senjutsu Chakra.
It was also possible that each had discovered Senjutsu Chakra independently, which would explain why the senjutsu of the different sage regions produced different effects.
The Sage Modes of the various regions were, after all, best suited to their own inhabitants.
Humans who trained in one region's senjutsu would take on that region's traits.
Thinking about it, Kimura Takuya seemed to recall that humans could breathe through their skin, too.
Their breathing efficiency was extremely low, though—far lower than that of those three species.
If he could improve his skin's ability to breathe and increase the Natural Energy in his cells,
could he develop a senjutsu that truly belonged to humans?
Then he could enter Sage Mode in an instant and use Senjutsu Chakra to open the Eight Gates. Wouldn't he be unstoppable?
Even Senju Hashirama, the God of Shinobi, could enter Sage Mode instantly and use it without limit, yet he died under mysterious circumstances after fighting Uchiha Madara.
Every one of the three sages had lived for over a thousand years, didn't they?
That had to be the result of mastering a senjutsu of their own.
How ironic. The secret of immortality that Orochimaru had sought in vain was hidden inside these little animals. Fate really was unpredictable.
After Orochimaru used Living Corpse Reincarnation for the first time, he'd already lost the ability to learn senjutsu.
To put it in the terms of cultivation, becoming an immortal required a complete spirit and abundant vital energy. The spirit was the soul, and vital energy was the blood.
Every time he used Living Corpse Reincarnation, it damaged his soul. With an incomplete soul, he couldn't learn senjutsu at all.
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