The Soul Function

Natsuhiko went straight to his study as soon as he got home.

Despite it being almost New Year's, the three little ones in the study were still diligently conducting their research.

Three-year-old child labourers, working sixteen-hour days, year-round with no pay.

Even capitalists would shed tears at this sight.

Natsuhiko often asked himself:

Perhaps the Shinobi world won't disappear, but is all this worth it?

However, at this moment, Natsuhiko didn't concern himself with them. After a brief greeting, he sat down and placed a scroll on the table.

This was a ninjutsu scroll that the Third Hokage had just copied from the Book of Seals using a unique technique.

Although Natsuhiko and the Third Hokage's proposed idea was not a lie, the Spirit Transformation Technique held much greater significance for him.

And now was the time to validate his ideas.

Natsuhiko took a deep breath and spread out the scroll.

**[Spirit Transformation Technique]**

**[Inventor: Unknown (Note: Don't ask, it's not Lord Tobirama—Third Hokage's note)]**

**[Ninjutsu Principle: ...]**

After carefully reading the text and the meridian diagrams several times, Natsuhiko exhaled lightly.

As he expected.

Although it seemed unrelated at first glance, the principles of the Spirit Transformation Technique and the Shadow Clone Technique had many similarities.

Both techniques involved lodging the mind into the chakra and then releasing the chakra externally.

The Shadow Clone Technique transformed the chakra, which contained part of the mind, into a physical clone.

The Spirit Transformation Technique, on the other hand, transforms the chakra, which contains the entire mind, into a spirit form.

Yes, the spirit formed by the Spirit Transformation Technique is essentially the same as various clones, all being chakra-formed carriers of consciousness.

Because in the laws of the Shinobi world, a pure soul is essentially useless.

Only by using chakra as a carrier can the soul obtain the ability to interact with the external world.

However, unlike the Spirit Transformation Technique, which actively uses this principle, the mental attachment in the Shadow Clone Technique is more like an internal function hidden within the chakra, uncontrollable and automatic.

Over the years, Natsuhiko continuously conducted symbolic analysis of the Shadow Clone Technique using a prototype, reaching a 99% completion rate.

The remaining 1% was the part involving this function.

After all, Natsuhiko's symbolic ninjutsu was relatively rigid, unable to use intuitive power to access that "internal function" like a natural person.

This meant Natsuhiko had to code this "function" himself to achieve a complete symbolic representation of the Shadow Clone Technique.

Due to this, the symbolic ninjutsu developed by Natsuhiko based on the Shadow Clone Technique—Shadow Puppet Technique and Flower Clone Technique—created clones without self-awareness.

It can be said he deliberately avoided this part.

Natsuhiko even speculated that the inventor of the Shadow Clone Technique, the great ninjutsu inventor Senju Tobirama, probably only discovered how to call this function without fully understanding the principle behind it.

Obviously, this part of the content was likely the most valuable aspect of the Shadow Clone Technique.

This method of splitting the mind, soul, or will into chakra to externalise it reminded Natsuhiko of the Otsutsuki clan's unique ability—the "Karma."

Karma refers to the Otsutsuki clan compressing their consciousness and body data into chakra and implanting it into another person, forming a black diamond-shaped mark.

The person implanted with Karma is called a vessel.

When an Otsutsuki dies, the Karma they left begins to unseal, gradually replacing the vessel's body with their data, ultimately achieving resurrection.

As long as Karma exists, the Otsutsuki can continually revive, surpassing death.

Undoubtedly, this soul function rooted in chakra's essence is one of the fundamental pieces of knowledge about chakra.

For Natsuhiko, who aspires to become the God of Chakra, it is an unavoidable challenge.

As he suspected, based on his recent observations, the Spirit Transformation Technique, which requires complete mental detachment from the body, does not merely call upon the soul function like the Shadow Clone Technique but makes deeper use of it.

Although far from fully understanding its essence, it's a good starting point, giving Natsuhiko direction.

Combined with the abundant materials on the soul provided by the Third Hokage, it should yield significant insights.

At least he is confident he can fully symbolise the Shadow Clone Technique within a few months.

Of course, the Spirit Transformation Technique itself is also a very useful ninjutsu that Natsuhiko won't pass up.

In the original work, Dan Kato demonstrated numerous abilities in the Fourth Shinobi World War, such as long-distance perception, high-speed flight, body control, creating a mental space, and chakra transmission.

Each of these abilities could be developed into various applications in Natsuhiko's hands.

Especially the chakra transmission, which gave Natsuhiko hope to supplement his insufficient chakra.

After all, Kushina had more chakra than she could use so that she could replenish his magic.

It's easy to see that the Spirit Transformation Technique, like the Shadow Clone Technique, is a highly potential ninjutsu.

This is why Natsuhiko ultimately gave up the Rashomon, which could exploit the underworld, and the Flying Thunder God Technique, which was impressively cool but had no friends.

However, the drawbacks of this technique are also evident.

Besides the vulnerability of the main body, like the Shadow Clone Technique, it continuously consumes chakra during use.

—Moreover, the consumption rate is far higher than that of the Shadow Clone Technique.

Even worse, when the Shadow Clone Technique consumes chakra to the point where it can't maintain its form, the clone disappears and returns to the main body.

However, the Spirit Transformation Technique, to better harm enemies and avoid backlash to the main body, lodges the entire mind into chakra, minimising the connection with the body, thereby losing the automatic return function.

This means if the chakra runs out before the user's soul returns to the body, they might turn from a living person to a dead spirit.

Therefore, ninjas using the Spirit Transformation Technique must constantly monitor their remaining chakra to ensure that enough chakra returns to their bodies.

Hence, Natsuhiko wanted to advise other transmigrators that if they often let their phones run out of battery in their previous life, they should avoid learning this technique.

This is why, despite being versatile and powerful, only some people are willing to learn the Spirit Transformation Technique.

Natsuhiko had similar concerns, hesitating to choose this ninjutsu.

High rewards always come with high risks.

They will ultimately abandon those who play with souls.

He feared ending up like Dan Kato, who died recklessly;

Or like Orochimaru, who became neither human nor ghost.

So, Natsuhiko originally planned to accumulate more experience over the years before delving into this field.

However, after talking with Mito, he felt a growing sense of urgency.

However, without Naruto, Asura's chakra would find another person to reincarnate into.

But without the protagonist's aura, whether bamboo shoots, char siu, or marinated eggs are able to save the Shinobi world is questionable.

So, to be safe, Natsuhiko decided to enhance his strength as much as possible so that he would not regret it later.

Alas, next year's research workload will be even heavier.

After calculating everything, Natsuhiko suddenly looked at the three little ones across from him.

"You three, come here for a moment."

The three little ones, who were working hard, were taken aback, then suddenly showed excited expressions and ran over.

"Main body, have you finally considered giving us a New Year's break?"

The three little ones said excitedly in unison.

Natsuhiko had a strange expression. Why would shadow clones need a New Year's break?

If the three little ones dared to take a New Year's break now, Natsuhiko couldn't imagine what they'd want in the future.

More importantly, he was about to tell them that he had fully packed their work schedule for the coming year.

Now, it seemed hard to speak.

Fortunately, a sudden inspiration struck Natsuhiko, reminding him of those geniuses who gave children exercise books in his past life.

So he smiled and said to the pregnant three little ones:

"Actually, I have a New Year's gift for you..."

Author Notes

I flipped through many manga and setting books and felt that Kishimoto needed to make clear distinctions between mind, mental power, soul, and chakra. You can find the counter-example statement, so I added some secondary settings that are available.

(End of this chapter)

T/N: For advanced 70 chapters, you may go to my pat reon.

Pat reon.com/ReidAstrea