Of all the Hyuga Clan's Gentle Fist techniques, the ones whose "form" best matched Naruto's impression of the Eighty Gods Vacuum Attack were undoubtedly Eight Trigrams Sixty-Four Palms and its advanced version, Eight Trigrams One Hundred Twenty-Eight Palms.
Those palm strikes, unleashed in an instant to engulf every chakra point on an opponent's body like a raging storm, certainly bore some visual resemblance to the "Eighty Gods Vacuum Attack."
Naruto knew perfectly well that his current mastery of Chakra Nature Transformation was nowhere near enough to imbue pure Taijutsu attacks with elemental effects such as searing flames or razor-sharp wind blades, as certain ninja could. But that did not mean he could not start practicing and preparing.
And he happened to know an excellent foundational ninjutsu that could serve as the starting point for everything.
If there was one ninjutsu that required no Hand Seals and offered plenty of room for modification, it had to be the Rasengan.
With that thought, Naruto stopped hesitating.
He held his right hand out level, palm upward, and settled his mind completely.
Under his precise control, two streams of chakra flowing in different directions immediately appeared in his palm, spinning, compressing, and colliding violently at unprecedented speed, with no fixed pattern whatsoever!
Chakra light shone in his palm, giving off a distinctive hum.
A sphere composed entirely of densely compressed chakra, radiating a steady, dazzling blue glow, slowly began to take shape in his hand!
Naruto had never specifically practiced the Rasengan before. Everything he knew about it came from his memories from before his transmigration and his theoretical understanding.
Still, thanks to his long-term training with Guy and the fine chakra control he had developed while working on Wood Release, his overall command of chakra was quite respectable.
He held his breath and focused, trying to recall and replicate the shape and rotation of the chakra sphere in his memories.
But...
Hiss-!
A sudden hiss rang out, like air escaping from a freshly punctured balloon!
The internal balance of the azure chakra sphere in Naruto's hand, which had only just begun to take shape, collapsed in an instant. The chakra churned wildly, scattering in every direction beyond his control!
The rampaging chakra turned into a sudden gale that swept through the room, sending papers flying off the desk and knocking the lightweight decorations by the window askew.
Amid the chaos, Naruto caught sight of the glass vase holding the balloon flowers out of the corner of his eye. The wind had toppled it, and it was falling toward the floor!
Almost without thinking, he immediately abandoned his attempt to maintain the already out-of-control Rasengan. His body lunged forward instinctively, and he deftly caught the flowers before they could hit the floor.
The chakra gale slowly subsided, leaving the room in disarray.
Naruto looked at the unharmed balloon flowers in his hand and sighed in relief. Then he glanced around the room, which the turbulent chakra had left a complete mess, and shook his head helplessly.
This attempt had given him a clearer understanding of himself.
Without the interference and disruption of the nine-tails chakra, my talent for learning ninjutsu really can come through more fully. It isn't like in the original story, where even the basic Clone Technique gave me endless trouble...
But it seems... I'm not quite as talented as I imagined. Or rather, things won't all be smooth sailing.
That was only natural. The Rasengan was far more complex than ordinary ninjutsu, and it was still difficult.
With practice, the current Naruto could probably learn to form one instantly in about an hour.
Still, he would have to wait until Jiraiya returned to the village before displaying the Rasengan in public.
Reasonable as that thought was, it left him feeling stifled.
He knew exactly which way to go, yet the lack of a guide and suitable resources forced him to slow down, or even wait. That feeling of being trapped in an invisible cage, constrained by all kinds of conditions, unable to unleash his full potential or grow quickly...
It was truly... unbearable.
He yearned for strength, yearned to break free of his restraints, but reality's barriers reminded him again and again that some things could not be rushed.
To Naruto, Konoha had long since ceased to be the warm, peaceful family filled with the will of fire portrayed in the story. It was more like an enormous, splendid, yet invisible prison.
The ever-present eyes of the ANBU, the villagers' veiled rejection, and the higher-ups' schemes and control were all like cold bars trapping him inside.
He felt utterly ill at ease here.
Like a young beast raised in captivity, he longed to break his bonds and breathe the air of true freedom.
An old saying flashed through his mind:
"When fortune favors you, heaven and earth lend their strength; when fortune turns away, even heroes cannot act freely."
He knew his moment had not yet come.
For now, he still had to endure and lie low, building his strength within this cage as he waited for the "opportunity" that truly belonged to him.
And the most fundamental source of strength he relied on was Wood Release.
If... if my Wood Release training could bring me to even half the strength of the First, Hashirama Senju...
Merely imagining that possibility set his heart surging.
Then, with power capable of reshaping the landscape and the might to unleash Nativity of a World of Trees, I'd have everything I needed to take on all of Konoha head-on and force my way out of this cage!
He had even considered the worst-case scenario: the ultimate threat he might face if he became an enemy of the entire village.
Once I've fully mastered Wood Release, I won't have to worry about Might Guy unleashing the Eight Gates Released Formation to hunt me down in order to protect the village, either.
Naruto knew just how terrifying Might Guy's Eight Gates Released Formation was. It was absolute power bought at the cost of one's life, enough to turn the tide of battle.
Guy was a man who could deliver the final, story-ending kick right at the beginning. He might have been somewhat weaker now than he would be five years later, but the only thing separating him from a fully unleashed Eight Gates Guy was probably the fact that he had yet to open all Eight Gates.
Even with some success in Wood Release, Naruto had no confidence whatsoever that he could face the world-shattering "Night Guy" head-on after Guy opened the Gate of Death.
He assessed the situation calmly: to so much as escape unscathed from Guy with the Gate of Death open, he would at least need to master Space-Time Ninjutsu on the level of the Flying Thunder God Technique.
Only instantaneous movement that ignored distance could give him a chance of evading that strike.
After opening the Eight Gates, Guy could use Taijutsu to step through the air and seal off the surrounding space with Evening Elephant.
How the hell was he supposed to fight Guy without learning Space-Time Ninjutsu?
As for obtaining the Flying Thunder God Technique, Naruto knew of two ideal opportunities:
The Mizuki incident at graduation.
That was his chance to access the Scroll of Seals in the original story.
Precisely because he was waiting for that day, Naruto did not even dare maintain a hundred-percent success rate when using the Shadow Clone technique in public.
As for Sealing Jutsu, he could simply say he did not understand it very well. Even if the Third Hokage took the scroll away, Naruto would not have to worry about being unable to practice Sealing Jutsu. The Nine-Tails had memorized all of it anyway.
The Konoha Crush Plan during the Chunin Ninja Exams.
When Orochimaru joined forces with the Sand Ninja to attack Konoha, plunging the village into chaos and reducing its defenses and surveillance to their lowest levels, it would be the perfect chance to slip into the secret repository of forbidden jutsu.
Flying Thunder God was ridiculously overpowered.
Even later, in the Otsutsuki era, Flying Thunder God remained an overpowered ability.