According to his father, Senju Tobirama, to become a Kage-level Shinobi, an individual's chakra control, chakra reserves, combat style, and spiritual power needed to cross a certain threshold.

But that wasn't the most important thing.

Because even an Elite Jonin-level or S-rank ninja could achieve those things.

What truly mattered was a dynamic mind and a rich imagination to acquire a deeper understanding of the Yang and Yin Release nature transformation.

They needed to understand how the balance of Yin and Yang, more accurately, the spiritual and physical energy formed chakra, affected chakra, and influenced every aspect of various ninja arts.

To become a Kage-level Shinobi, individuals should be able to use the aspects of Yin and Yang Release to alter their Ninjutsu the way they wish, boost their raw physical strength, sharpen their mental power, and make their Genjutsu deadlier.

In a nutshell, they needed to master the very foundational energy that made them a ninja—chakra.

They shouldn't just use its base, rigid form. They needed to be capable of influencing its very essence by altering the chakra's Yin and Yang aspect ratio.

If a ninja could not do it, even if they had enough firepower to kill a Kage-level ninja, they could never cross the boundary to reach the Kage-level themselves.

Even if they had more chakra, more Ninjutsu, better spiritual power, and greater chakra control, they could never achieve the Kage-level themselves.

Such ninjas were destined to stay glass cannons.

They were destined to remain mundane, ordinary humans.

After all, only by reaching the Kage-level could a ninja achieve an innate defense stronger than most ninjas, a lifespan surpassing most ninjas of similar level of bloodline below the Kage-level, immense control over chakra, and a dramatic increase in offensive capabilities.

Of course, the process of breaking through the Kage-level was gradual. In most cases, this gradual process took a few weeks to a few months, depending on the individual.

It was a Shinobi world, not an Xianxia or Xuanhuan cultivation world. There was no dramatic breakthrough, no breaking through to the Kage-level during a fight.

The process of advancement was gradual and subtle.

Of course, there were some exceptions, too.

For example, if you had a three-tomoe Sharingan that evolved into a Mangekyo Sharingan, then boom—you could cross the threshold of the Kage-level and understand the essence of chakra and Yin and Yang Release quickly.

Although there were solid reasons behind this, it didn't make the Mangekyo Sharingan any less buggy.

No wonder people of this world treated Sharingan as an absolute cheat code.

Other people: Worked hard for years to finally cross the threshold of the Kage level.

The Uchiha people: Received intense mental trauma, awakened Mangekyo Sharingan, and boom—Kage-level achieved.

Unfair? Yes.

Buggy? Yes.

Cheating? Yes.

But Seimei loved it. Because he also had a pair of Sharingan.

When others used buggy powers, you would call it cheating. But if you were the one who had cheats, you would call it power leveling.

Now, back to the main point…

What did inventing new Jutsu or significantly modifying the existing ones have to do with reaching the Kage-level power?

"I see now, Father."

"The answer was always in front of me. I just didn't know how to even look for it."

"Now, I understand why you were so sure that I could reach the Kage-level even without evolving my Sharingan to the Mangekyo Sharingan."

"No wonder you said that those who had the courage and capability to invent new Jutsu or significantly modify the existing ones to make those Jutsu unique to them had already met the main prerequisite to enter the Kage-level."

Seimei muttered as his mind raced.

He began to think about the potential implications of this revelation.

To gain an automatic chakra cloak, improve your physique, and gain solid defense, you need to understand the essence of chakra.

You need to be able to understand and manipulate Yang Release and Yin Release to a certain extent, and use their application to gain the unique abilities of a Kage-level Shinobi.

And there was no better way to understand the essence of Yin and Yang nature transformation than inventing new Ninjutsu and significantly modifying the existing ones to match your needs.

Let's take a normal elemental Ninjutsu as an example.

When most ninjas use Ninjutsu, they form hand seals to guide the chakra in a specific pattern. Once the pattern is formed, they pour chakra into it, transforming the chakra into a specific nature or element before releasing it.

In these cases, since the pattern is fixed, the type, power, element, minimum chakra requirement, and shape of the Ninjutsu are also fixed.

If you guide the chakra to form the pattern of the C-rank Ninjutsu Great Fireball Technique and pour chakra into that pattern, the chakra you used can transform into fire and release a giant fireball.

The power of the Ninjutsu can be increased by investing more chakra, refining chakra control, and increasing the level of your fire nature transformation affinity.

Suppose your chakra control and fire nature transformation affinity are good enough. In that case, you can decrease the chakra cost of the Ninjutsu, make the fire burn hotter, and control the timing of the fireball's detonation.

But that's the limit.

The chakra you are drawing upon to form the Fireball is a combination of physical and spiritual energy, more accurately, the combination of Yang and Yin energy in a 1:1 ratio.

And this 1:1 ratio makes the chakra very stable.

Most ninjas just think that they are using chakra to cast a Ninjutsu. They have no idea that they are using a fixed, stable combination of Yin and Yang energy to cast their Ninjutsu.

Even if they knew, most never bothered exploring them.

They stay stuck with the conventional Ninjutsu, rarely thinking about modifying the Ninjutsu on a fundamental level.

For example, most of them could unleash a powerful gust of wind using the Wind Release: Great Breakthrough Jutsu.

That was the fundamental form of the Jutsu. Even if they spent more chakra and improved their wind nature affinity, they could only release a more powerful gust of wind, covering a larger area.

But that was not how Seimei did it. Once he mastered the Jutsu to LV5, he began adjusting the ratio of Yin and Yang aspects of the chakra and the Jutsu.

He actively took control of the Yin aspect of the chakra to form hidden wind blades within the gusts of wind of the Wind Release: Great Breakthrough Jutsu.

Seimei even used the Yin aspect to make the coverage of the Jutsu either wider or narrower.

After all, Yin Release was the energy that could shape things and give shape to things out of nothingness. It was like creating a hollow vessel without energy and life.

Then he used the Yang aspect of the chakra to actively supply the hollow vessels with energy.

In the case of the Great Breakthrough Jutsu, the Yang aspect of the chakra gave the wind blades formed inside the gusts of wind the power to become sharper, faster, and deadlier.

By pouring the additional Yang energy he took from the chakra, he could also make the original gusts of wind fiercer.

It was this ability to modify the ratio of Yin and Yang energy of the chakra and use those energies to actively modify the essence of the Jutsu on a fundamental level that made it easier for Seimei to develop new Ninjutsu with precise control and shape transformation capabilities.

Of course, doing such modifications needed him to use twice and even thrice the amount of chakra than usual for the same Ninjutsu.

Then again, doing these things improved his Yin and Yang Release affinities greatly [A/N 1].

Now, Seimei just needed to grind his ability to modify the ratio of Yin and Yang energy in his chakra to a point where doing it becomes an almost instinctive thing for him.

Once he could achieve that, he would be infinitely closer to stepping into the rank of the Kages.

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[A/N 1: Seimei had it easier because he was born with Yin and Yang Release affinities.

Most ninjas needed to develop these non-standard affinities from scratch if they wanted to achieve the same feat.

However, Yin and Yang were incredibly elusive. So, most didn't bother with it. Who would want to grind for decades only to develop these elusive affinities?

Most wouldn't.]

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