[Modifying Ninjutsu]

After the rigorous training session with Kurenai in the 'Forest of Death,' Sasuke swiftly headed home to recuperate from his accumulated fatigue.

The following day, Sasuke dispatched a shadow clone to attend the academy in his stead, and found himself back at the secluded training ground after his morning training session, contemplating his weaknesses after the intense battle.

'There are three main issues I should deal with,' Sasuke thought, his mind delving into the challenges ahead. 'Firstly, I must modify my Ninjutsu to make them both more potent and versatile. Secondly, there is an obvious need for a defensive Ninjutsu. Then finally, there is the necessity of improving my Taijutsu, something I don't yet have a clear idea about and might have to consult Guy about it.'

Standing motionless on the training ground, Sasuke immersed himself in a quagmire of thoughts. "I guess I'll start off with my first problem and attempt to modify my Ninjutsu," he muttered, holding his chin in contemplation.

To address this, Sasuke decided to release his Great Fireball Jutsu and see if there was anything he could add to it. Without any hand seals, he inhaled deeply and then spat out a large fireball. However, as he witnessed the Jutsu colliding with a tree and causing a substantial explosion, he soon recognised a rather glaring issue.

'Was it always this slow?' he wondered in confusion. The Jutsu's speed and linear path made it easily dodged, and its power was limited. While Sasuke had typically used the Jutsu as a distraction or to limit an enemy's movement, the results now made him realize its potential could be greatly enhanced with increased speed.

Sasuke closed his eyes, allowing his mind to race as he sought a solution to overcome this inherent limitation. Lost in thought, time slowly passed.

Abruptly, his eyes shot open, glowing with a mixture of shock and fervour. "Why didn't I think of this?" Sasuke exclaimed.

He stretched out his hand, palms facing upward, as a ball of flames materialised above it. Golden yellow flames bespeckled with deep blue dots gave the fireball an abstract beauty.

This was something Sasuke realised earlier, that he could switch between using normal flames and this unique variety, which he did in his prior fight, keeping a potent card hidden for strategic use.

With newfound excitement, Sasuke arched his arm back and launched the ball at a tree beside him. Unlike before, this fireball moved at a blinding speed before causing an explosion upon impact.

'It worked!' Sasuke thought. The simplicity of the idea astounded him. He hadn't considered it before, likely influenced by the conventional portrayal of Fire Style Ninjutsu being projected through the mouth in the anime.

This conventional method was likely a result of most ninjas relying on hand seals to produce Ninjutsu, a technique Sasuke had come to surpass. While other ninjas attempted to reduce the number of hand seals or increase their speed, Sasuke, with his proficiency in Fire Style and precise chakra control, had transcended the need for such conventional constraints. This realisation made him understand, that he might be the only one in the ninja world who could perform such a thing for now..

Now, he realised that this method, generating Ninjutsu from his hands or other limbs, not only increased the speed but also made it less likely to be noticed by an enemy, as they wouldn't be accustomed to such a technique.

However, Sasuke's experimentation was far from over. He quickly summoned a shadow clone and instructed it to replicate the previous steps but with an added twist – to pump more chakra into the generated fireball and attempt to condense it.

The clone diligently followed Sasuke's instructions, condensing another fireball in its hand and infusing it with more chakra. Sasuke observed in fascination as the ball of fire expanded and contracted repeatedly. However, sensing an anomaly, Sasuke began to cautiously back away from the clone.

Boom

A mirror image of himself perished under the force of the explosion. Sasuke winced, hoping that no one had heard the resulting blast.

"That might take a while to get used to," he muttered, giving his clone a moment of silence before contemplating the experiment's results.

'Though it makes the fireball more powerful, it's highly unstable and takes too much time to perform. However, there is potential in it. I could try to develop this further with my shadow clones,' Sasuke pondered.

His next idea also aimed to increase the potency of his Jutsu. The Rasengan training he had undertaken proving to be rather beneficial. Sasuke summoned another shadow clone, instructing it to slowly generate a fireball from its hands and then modify it.

'Through my training of the Rasengan, I've become familiar with the rapid rotation of chakra. It might be possible to add this to my Fire Style Jutsu,' Sasuke contemplated. Slowly, he watched as the ball of flames in the clone's palms began to rotate. The ball gained speed, and at Sasuke's command, the clone immediately threw the fireball.

It moved faster than ever, shooting through several trees before creating a blinding explosion.

"Damn," Sasuke exclaimed in shock.

"That doesn't sound like something that could be easily concealed," Sasuke turned around slowly and asked his clone.

"No, no it does not," the clone responded.

"However, it's not like it's my problem. Good luck, boss!" Sasuke watched in silence as his clone disappeared into a puff of smoke.

Sigh

"Someone will probably come to check on this training ground soon. I'll have to leave and most likely not return here anytime soon," Sasuke briefly considered before vanishing, his blurry form darting across rooftops until he reached home.

Once at home, Sasuke promptly prepared lunch for himself and took the time to recover his chakra.

'How can I acquire some defensive Ninjutsu? Basic Earth or Water Style Jutsu from the academy library might be a start, but they wouldn't offer protection against stronger attacks,' Sasuke mused, pondering the path to obtaining a defensive Ninjutsu.

While lost in thought, a scene from the anime flashed in his mind.

A young boy stood on one side of the arena, a strange green insignia marking his forehead, and his pale lavender eyes lacking pupils indicates his origin—a Hyuga. On the opposite side, a familiar blonde child charged towards the Hyuga, who began to rapidly spin and release chakra from his tenketsu points. Naruto, knocked back by this peculiar defensive technique, was left bewildered. The Hyuga, seeing his opponent's confusion, snorted disdainfully.

"You underestimate your own futility. This is the Hyuga Clan's guarded technique—'Revolving Heavens,'" the Hyuga declared, his words laced with confidence. "Admit your insignificance; your feeble attempts are but insignificant against this impregnable defence."

The image faded from Sasuke's mind, replaced by numerous ideas and concepts that began to float around his head.

'How could I forget about that?' Sasuke wondered.

Sasuke couldn't replicate the exact technique involving chakra release from tenketsu points, due to him not being a Hyuga. However, the concept gave him a new idea on how to create his unique defensive Jutsu.

He realised that it was only afternoon, leaving him with ample time to embark on another endeavour.

"Though it's not beyond my capabilities to gradually develop this Jutsu on my own, it would be inefficient not to seek out a Hyuga practitioner performing it. With my Mangekyou, I can analyse its underlying principles and craft my own Jutsu with it as my foundation."

Determined to act swiftly, Sasuke summoned a shadow clone and instructed it to infiltrate the Hyuga Clan's territory. The clone, would be taking on the appearance of a Root operative reminiscent of Sasuke's anime memories, once within the clan grounds.

Unconcerned about potential discovery, Sasuke relied on the first layer of his disguise—a Root Operative. The second layer, the power of his Sharingan, he allows the casting of a subtle Genjutsu on any witnesses, veiling his true identity and ensuring his transformation remained undetected. Furthermore, it would allow the clone to reduce it sense of presence within the clan grounds. This meticulous approach would allow the clone to move through the Hyuga Clan land without arousing suspicion.

While awaiting news from his shadow clone, Sasuke decided to dedicate his time to practicing a new type of Fuinjutsu seal—the Gravity Seal. Which held the promise of being rather beneficial for his future physical training.

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The clone executed a brief reconnaissance mission around the Hyuga clan's location, identifying an average male from the branch family as its target. Using a Genjutsu, it lured the unsuspecting Hyuga into an inconspicuous alley, ambushing and interrogating him about the whereabouts of the main branch's training ground.

Aware that such actions might arouse suspicion, the clone decided to turn the situation to its advantage, planning to present Danzo with a substantial gift.

Transforming into the Hyuga's appearance, the clone confidently strolled through the entrance, subtly influencing the guards with an illusion.

'This was easier than anticipated,' it thought, slightly puzzled by the effortless entry. However, it recalled a past incident where a ninja from Kumogakure had managed to steal the clan patriarch's eldest daughter several years ago.

Upon transforming into a Root ninja and leaping over a wall, Sasuke found himself at the corner of the training ground. The sparring session unfolding before him drew his attention. Two men, both under 30, engaged in a dynamic exchange of blows. The clone activated its Mangekyou to closely observe the situation.

As they momentarily backed off from one another, one them launched an attack first.

"Eight Trigrams: Vacuum Palm!" He shouted vigorously.

'Oh, I forgot that people shouted out the names of their techniques over here for some reason. Then again it could be because this is a spar. I mean, I hope thats the case...' The clone recoiled in cringe as it watched on.

The other defended against it whilst shouting the name of his own technique, "Eight Trigrams: Palms Revolving Heaven."

'This is it!' the clone thought with internal excitement, keenly analysing and comprehending the principles behind the technique.

As the spar concluded, the clone, satisfied with the acquired information, dispelled itself. Unbeknownst to it, a pair of pale lavender eyes observed its disappearance...