Naruto : Reborn As Sukuna Haruno

"Just as I expected, the academy was no different than any other school. Besides some normal ninja-related stuff and no doubt a lot of 'Will of Fire' fixed into the history of Konoha, there was nothing to learn there. And that for my next few years…" A rather exaggerated sigh escaped his mouth.

After the academy, he went back home, had something to eat, and immediately bolted out of the Haruno residence.

Though even then, he wasn't able to escape his new mother's demands. Now inside his shorts pocket lay a list of items he had to get from the market before he could go back home.

Even his plea that he wouldn't be back soon was disregarded. She was fine with it as long as he was back by evening.

Truly, women of this world are fierce… 'How so troublesome…'

Once he was out of the house, he made his way to an isolated training area. Though no area is completely isolated, his demands weren't big. There were many areas around Konoha suitable for an academy student like him to begin his training.

Once he found a place he was looking for, without wasting time, he got onto the main reason he was here.

Checking out his powers.

"Chakra is created by the mixture of both physical and spiritual energy in this world. While Cursed Energy is derived from the negative emotions of human beings. I'm not sure whether this is applicable to other living beings though. JJK left out many of these smaller key details, so forming a solid idea from just the show is not possible," he muttered and huffed in annoyance.

Good thing he had Sukuna's memories to know how things worked. Otherwise, he would be aiming in the dark.

His current goal was to check how much Cursed Energy he had, try to control it, and also test both Dismantle and Cleave.

Earlier this morning was the only time he had used his Cursed Energy, and that was completely out of his control. Hell, he didn't even intend for his CE to go out of control like that.

This further showcased the fact that he needed training. Thus, why he was here. Unlike normal sorcerers, who don't possess a lot of Cursed Energy, he was different. His Cursed Energy reserves were similar to Ryomen Sukuna, who had the highest reserves in JJK.

Yuta, arguably the Naruto of JJK in terms of reserves, himself said that Sukuna's Cursed Energy reserves were twice his own. That was no common statement.

Gaining control over his CE was important for him, not only to be able to use his powers but also for others' and his own safety. Yuta accidentally cursed Rika, his childhood sweetheart, and the result was the birth of the strongest Cursed Spirit of the modern era. Only second to Sukuna, and the King of Curses was in fact a sorcerer before he turned into a curse.

Rika's existence itself defied how strong Yuta's Cursed Energy was. Of course, so was his love for that girl.

"While Chakra control mostly falls on one's training and talent, Cursed Energy manipulation is more dependent on a sorcerer's mental state. In fact, much of Jujutsu's power is defined by a sorcerer's mental state.

So to get control over this enormous Cursed Energy I have, I need to first gain control over my own emotions…

Easy to say, but much harder in practice," he muttered and let out a sigh. Yuji in the show at least had a doll and a bunch of movies to help him train.

How was he supposed to train?

"Maybe Jiraiya's Icha Icha Paradise?" He paused and then looked at his pants. "Will it even stand up at this age? Or do I need to wait until puberty? Shit, I don't even remember how it was back in my time."

Shaking his head, throwing his inner demons out, he decided to do it the old-fashioned way.

"Pure old meditation."

It didn't last very long though. While his mind was that of an adult—well, he was almost out of his teenage years, if not entirely an adult—this body of a 5-year-old child wasn't ready to just sit down and relax for more than 5 minutes.

After utterly failing for the next hour or so to keep his mind out of distractions and meditate, he finally gave up.

"Baby steps…"

"Time for the good stuff then." He sprang up to his feet, ready to use Cursed Energy and his innate technique finally.

This was definitely not the reason he wasn't able to meditate. Not at all…

Walking up to a tree and making a fist, he channelled his Cursed Energy to his small hand… he could see how unstable the energy was, and even keeping the Cursed Energy wrapped around his fist for a few seconds was hard.

"Characters in the show made it look easy." Sighing, he waited until he got a little hang of the energy manipulation, then finally threw his fist out.

BANG…

The entire tree shook, rattling as leaves fell. A small indentation, a dent, was left behind on the trunk where the fist connected.

Looking back at his fist, he kept staring at it, a complication on his face.

"No pain, but it feels numb. This isn't even because of the punch. I wasn't able to handle the backlash of the energy eruption.

Energy shattered before it could actually do much damage to the tree. Best estimate… out of 100% CE I used, only 5% actually went towards the attack and the rest just shattered away, dissipating into thin air."

"Hmm…

Let's check out the slashes as well." He prepared himself and took a few steps back, just in case he messed up.

Raising his two fingers—index and middle together in a gun-like motion—he pointed them towards the tree and imagined how the slashes were supposed to work and look.

With Sukuna's memories, he knew that at long distance he could only use Dismantle, as Cleave required direct touch to activate. This of course was only valid normally, since inside a domain the sure-hit effect applied, meaning Sukuna could use both.

Now, anyone would say: why even bother using Cleave in the first place? Both are cutting attacks and one can be used from a distance, so stick with only Dismantle, yes?

Well, no. Dismantle, while giving a range advantage, is also far weaker than Cleave. Not to mention, Dismantle is a very basic cutting attack; Cleave, however, can be adjusted and modified to adapt to a particular target.

For the time being though, Sukuna took a deep breath in and imagined an imaginary line intersecting the tree trunk.

"The line of slash, the trajectory of the slash, and finally the power behind it…" he imagined and went step by step in his mind. It was important since this might be the only "Jutsu" he could use in his life.

And with that, he poured Cursed Energy out and flicked his fingers across, acting as a trigger to initiate the technique.

Unlike what he anticipated, it wasn't an invisible slash. No… he was able to see the slash. Though he only caught glimpses of it since it was ridiculously fast. It was like a shadow that flickered into existence for just a heartbeat and then vanished.

Swoop…

Before he knew it, a long slash appeared on the trunk. A deep cut, enough to kill any normal person easily. And this was a tree trunk… real flesh is far less sturdy than this.

He was left gaping. He wasn't expecting it to work this well. Sure, the tree was still standing strong. It wasn't falling any time soon.

But this attack was already lethal for most shinobi, let alone civilians.

"I didn't expect it to work this well. According to the earlier estimate, I believe around 30 to 40% of the energy was actually used in this attack, unlike the earlier one where only 5% was."

No doubt Gojo said that 80% of a sorcerer's strength depends on their talent. And here, talent means how much Cursed Energy one is born with and what their Cursed Technique is.

The Naruto world is also similar in many ways. Bloodline factors and high Chakra reserves make a huge difference in a shinobi's potential.

However, this test cleared his doubts. Using an innate technique is much easier than just raw Cursed Energy.

Just like it was explained in the story: if Cursed Energy is electricity, then the innate technique is like an electronic device.

From a smartphone to an electronic toaster… they all run on electricity. However, they do different things. Regardless, they are always more useful than just plugging out a naked electric wire and tossing it around.

Cursed Energy and technique also share a similar relationship.

This also explains the refinement of techniques and the growth a sorcerer experiences over time.

While everyone has fixed Cursed Energy reserves, their efficiency in using the energy or a technique can be altered and mastered throughout one's life.

It's just like the difference between an LED bulb and a halogen bulb. LED bulbs are more efficient, last longer, and generate less heat compared to halogen bulbs.

A halogen bulb needs 10 times the energy to produce the same amount of light compared to a modern LED bulb.

However, after first using this technique, he already spotted a concern. In JJK, Sukuna's slashes are completely invisible.

Only Mahoraga, who adapted to the slash attacks, and perhaps Gojo with his Six Eyes, could see them. However, here, he clearly saw the slash.

That was concerning. If they are visible to others as well, then they could also dodge it. And if that's the case, then their lethality goes down drastically.

This was indeed concerning. However, it could simply be because it was his own technique. Of course, it makes sense he can see them. The only way to know was to test it out.

"I have to master Cursed Energy manipulation and refine this technique first though," he said to himself, setting the first major goal in this world for himself.

The last technique which remained was, of course, Cleave… however, he wasn't going to use it on the tree. No doubt, being the stronger of the two techniques, it might completely cut the trunk.

He would rather not be called "Pastekuna" anytime soon.