Natsuhiko obtained this technique from Mito yesterday and has studied it multiple times. However, what surprised him was that the Yin Seal training method he received was not complete.
It wasn't that Mito was withholding information from him; instead, the Yin Seal itself had always been incomplete.
According to the scroll's records, the Yin Seal, passed down through the generations of the Uzumaki clan, has a very long and ancient history, dating back to the era of the Sage of Six Paths.
Unlike Natsuhiko, who imagined it to be merely a chakra storage technique, the Yin Seal theoretically has many uses and forms a complete system of ninjutsu.
However, similar to the history of the development of the Rune System, the inheritance of the Yin Seal has gone through many disruptions, with parts of it being lost over time.
As a result, the scroll that records the more complete aspects of the Yin Seal only contains two functions: storing chakra and stimulating bodily activity to maintain youthfulness. The other functions have been reduced to mere fragments and are not complete systems.
One thing that caught Natsuhiko's attention was the repeated mention of the term "Hundred Heroes" in the scroll's text.
This term actually refers to those who fully master the Yin Seal, gaining an amount of chakra and combat power equivalent to that of one hundred heroes—something even Jiraiya would find overwhelming.
In fact, this entire system was initially called the "Technique of the Hundred Heroes"!
The diamond-shaped mark formed by the Yin Seal was also known as the "Mark of the Hundred Heroes."
However, due to the loss of many parts of the technique, leaving it with almost only the chakra storage function, it no longer lived up to the name "Hundred Heroes," so it is rarely referred to that way anymore.
It was only when Natsuhiko read this that he finally understood something.
Although Tsunade later developed the Technique of the Hundred Heroes in the Boruto series, Sakura still claims that it is an ancient ninjutsu.
This, of course, isn't Sakura subtly hinting at Tsunade's age.
More likely, Tsunade later developed the Yin Seal from a medical ninjutsu perspective, even inventing the Creation Rebirth, an S-rank medical ninjutsu that greatly enhances the Yin Seal's power in battle.
Confident that she had completed the Yin Seal, Tsunade brought back the name of the Technique of the Hundred Heroes.
However, Tsunade's Technique of the Hundred Heroes is probably still inferior to the original.
Natsuhiko finally understood why Mito had so quickly taught him the Yin Seal, the Uzumaki clan's most precious ninjutsu.
She even went as far as sparring with him beforehand, letting him realise his shortcomings in chakra capacity and thereby increasing the appeal of the Yin Seal.
It seems she wanted to leverage Natsuhiko's unique ideas and strong ninjutsu development abilities to supplement the Yin Seal.
This way, Kushina, who was learning the Yin Seal alongside Natsuhiko, would also greatly benefit.
So, while it may seem like Natsuhiko got the Yin Seal for free, Mito was also getting something out of him.
However, Natsuhiko finds developing his Technique of the Hundred Heroes very appealing, so he has no choice but to take Mito's bait.
After all, even in his early plans, the Yin Seal's "battery" function had an irreplaceable role in his Chakra God project.
In fact, the chakra capacitor Natsuhiko developed was actually a byproduct of his earlier attempts to copy the Yin Seal.
Unfortunately, the chakra stored in the capacitor still undergoes certain changes in nature, making it impossible to inject back into the human body. It can only be used to power rune constructs.
Otherwise, Natsuhiko's chakra deficiency issue would have been resolved long before he learned the Yin Seal.
So, Natsuhiko has been eyeing the Yin Seal for a long time and has already devised a series of application plans for it.
It's like preparing a bunch of dipping sauces, just waiting for the dumplings to be served.
Moreover, the Yin Seal uses rune techniques to automatically and precisely release small amounts of chakra to stimulate cells throughout the body and maintain youthfulness. This method gives Natsuhiko a strong sense of déjà vu.
Because this is very similar to his approach to applying rune ninjutsu through his intelligent brain, both methods break free from the constraints of sealing techniques and use rune techniques to manipulate the body.
The difference is that the intelligent brain's carrier is a chakra metal ball, while the Yin Seal's carrier is the user's body and chakra.
Also, the intelligent brain operates on the chakra provided by Natsuhiko, while the Yin Seal can operate by consuming the stored chakra.
So, learning the Yin Seal not only gives Natsuhiko a backup power source for his intelligent brain but also offers significant insights into how he can further develop its applications.
At the very least, it has given him a new direction for upgrading his chakra-intelligent brain, which had been stagnating for a while.
However, all these things are still castles in the air for now.
Although the Yin Seal ultimately forms a diamond-shaped mark on the forehead, the rune technique needed to create it must be formed throughout the entire body.
So, in addition to sealing techniques, one also needs advanced medical ninjutsu knowledge, a deep understanding of the body's various parts, and the ability to immediately self-repair in case of any mishaps, even to reach the threshold of learning the Yin Seal.
Even Natsuhiko, who is not very knowledgeable in medical ninjutsu, has to start learning from scratch.
Therefore, in the coming days, after giving Kushina a quick review of the Yin Seal, Natsuhiko opened another scroll, summoning a mountain of medical ninjutsu books.
These were the medical ninjutsu materials that Mito had specially prepared for them.
And this was only a part of it...
"..."
The two exchanged a knowing glance, both showing troubled expressions.
...
A few days later, on the training ground of the Ninja Academy.
Obito's first-year Class A was in the middle of a taijutsu lesson.
With the final exams approaching, the class focused more on sparring, which increased the students' combat experience.
After being called out by the teacher, each student would step onto the field to spar in taijutsu with their selected opponent.
"Konoha Whirlwind!"
There was a flash of movement, and a girl appeared in front of a tall boy, landing a powerful mid-air kick that sent him flying.
The swift and decisive action gave the watching students a sense of déjà vu, causing them to glance at Guy, who was nodding approvingly from the side.
Why do Rin's combat moves look more and more like Guy's lately?
Could it be...
The students who didn't know about Natsuhiko's training suit couldn't help but wonder.
But the real question was, why do Obito's combat moves look exactly like Guy's, too?
Could it be...
Is there something strange going on here?
The taijutsu teacher, aware of the inside story, could only feel both gratified and helpless as he praised, "Excellent, Rin. You've made great progress recently. If you keep it up, you should be able to rank in the top five of the class by the finals."
"And the rest of you, learn from Rin!"
Though the taijutsu teacher used Rin as an example to motivate the other students, he knew that Rin's improvement was not something the others could replicate.
Her rapid improvement was primarily due to the training suit developed by that guy Natsuhiko.
Of course, Rin's daily hard work shouldn't be overlooked either.
In simple terms, it was a combination of technology and hard work.
As a result, the taijutsu teacher couldn't help but feel conflicted.
While he was pleased with Rin's progress in taijutsu, knowing that all of it was due to the sealing techniques teacher and not himself made him feel awkward.
He was distraught because he had heard that this training suit would be officially introduced to the school next year.
He was concerned that the training suit would completely replace his role.
Ever since Natsuhiko came to the school, the job of a teacher has become increasingly competitive.
He once thought he would hold this job until retirement, but now he's not so sure...
Shaking off these distracting thoughts, the taijutsu teacher picked up the list and called out the names of the next pair of students to spar.
"Kakashi Hatake versus... Obito Uchiha."
The taijutsu teacher's voice hesitated slightly, and he looked at Obito with a bit of resignation, asking, "Obito, are you going to forfeit this time as well?"
(End of Chapter)
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