The cave was brilliantly illuminated, as though it contained an entire sky full of stars.
Hayashi looked closer and quickly realized that the "starlight" filling the cavern was actually produced by a single beam of light being refracted repeatedly through countless glass mirrors, making the entire interior as bright as day.
He slowly stepped through the main entrance, and the first thing that caught his eye was a massive stone wall.
Hayashi was instantly captivated by the text engraved across its entire surface.
Walking closer, he reached out and gently touched the stone. After carefully deciphering the writing for a moment, his eyes widened in shock.
"This is... the training method for Yin-Yang Release!"
The so-called Yin-Yang Release encompasses several different concepts, including Yin Release, Yang Release, Yin-Yang Ninjutsu, and most importantly, the Art of Yin-Yang Release itself.
These were entirely different things.
A ninja's chakra consists of seven attributes: Wind, Lightning, Water, Fire, Earth, Yin, and Yang.
Generally, abilities related to the body and chakra vitality fall under the Yang attribute.
The Akimichi Clan's Multi-Size Technique, Medical Ninjutsu, and Hashirama Senju's extraordinary regenerative abilities are all manifestations of Yang Release.
Meanwhile, the Nara Clan's Shadow Possession Jutsu and nearly all Genjutsu belong to Yin Release.
These are collectively known as Yin-Yang Ninjutsu.
Compared to the five elemental nature transformations, Yin and Yang Release are much rarer. Many are secret techniques exclusive to major clans, but they can still be encountered and learned.
The Art of Yin-Yang Release, however, is entirely different.
As its name implies, it is the fusion of Yin and Yang Release, not merely the manipulation of Yin and Yang chakra attributes.
Its most fundamental and terrifying ability is the power to create something from nothing and breathe life into it.
Yin Release represents spiritual energy. Through it, forms can be created from nothingness.
Yang Release represents physical vitality. Through it, life can be bestowed upon those forms.
That is the true Art of Yin-Yang Release.
Back then, the Hagoromo Ōtsutsuki used the Art of Yin-Yang Release to divide the Ten-Tails and create the Tailed Beasts. Later, Naruto Uzumaki also used Yin-Yang Release to recreate Kakashi Hatake's eye.
And its capabilities certainly did not end there.
Techniques infused with Yin-Yang Release also possess the ability to nullify all Ninjutsu. In other words, even an Edo Tensei body would be unable to regenerate after being struck.
In the original timeline, after becoming the Ten-Tails Jinchūriki, Obito Uchiha used a Truth-Seeking Orb empowered by Yin-Yang Release to sever Minato Namikaze's right arm, preventing it from regenerating despite his Edo Tensei state.
Likewise, Madara Uchiha later used a Six Paths Staff to sever Minato's left arm, producing the same effect.
However, this was not an innate property of the Truth-Seeking Orb itself.
It was the power of Yin-Yang Release.
Only the Art of Yin-Yang Release can negate all Ninjutsu.
A Truth-Seeking Orb is fundamentally a high-density sphere of chakra created by combining all seven chakra natures.
In other words, it is primarily a technique based on overwhelming power rather than a special ability.
It can change shape freely, serve both offensive and defensive purposes, be used in close combat or at long range, and even explode with devastating force.
But by itself, it cannot negate all Ninjutsu.
Only when Yin-Yang Release is incorporated into it does it gain the ability to prevent regeneration.
In the original timeline, when Obito had only just become the Ten-Tails Jinchūriki, he had yet to master the finer applications of Yin-Yang Release. At that time, he merely attacked the Third Hokage using Truth-Seeking Orbs, allowing the Third's Edo Tensei body to recover. Even the Second Hokage had managed to grab one with his bare hands.
Later, after Obito fully mastered Yin-Yang Release, Minato's severed arm could no longer regenerate.
Therefore, although Truth-Seeking Orbs were powerful, the true key was always the Art of Yin-Yang Release itself.
Hayashi had absolutely no intention of becoming the Ten-Tails Jinchūriki.
Nor did he want to rely on a temporary blessing from the Six Paths Sage. Such power was fleeting and ultimately borrowed.
Therefore, the complete Art of Yin-Yang Release engraved upon this stone wall represented his only opportunity to truly learn it.
Fortunately, Hayashi possessed near-photographic memory.
Even so, to reinforce his understanding, he carefully copied everything onto a scroll while memorizing each section. Once he finished, he closed his eyes and recited everything repeatedly until it was firmly etched into his mind.
He already possessed chakra from all nine Tailed Beasts.
He also carried Hashirama's cells, effectively inheriting the power of Ashura.
From a certain perspective, the current Hayashi was even stronger than Naruto in Nine-Tails Chakra Mode.
Naturally, he should also be capable of learning the Art of Yin-Yang Release.
After committing everything to memory, Hayashi walked past the stone wall and continued deeper into the cave.
The layout no longer resembled a tomb.
Instead, it felt more like a shrine.
After passing beneath a massive torii gate, a three-story pagoda came into view.
Its architectural style was completely different from that of the current ninja world.
More accurately, it resembled the architecture of thousands of years ago.
Hayashi guessed that Ōtsutsuki Hamura had rebuilt this place based on memories of his former home.
He continued onward, passing the pagoda and several other ancient buildings.
Eventually, a narrow path stretched out before him.
At first glance, it seemed endless.
Hayashi walked slowly until he finally reached the end.
Nine stone steps led up to a transparent crystal coffin.
Inside lay a withered white skeleton.
Was this really the remains of Ōtsutsuki Hamura?
Unlike the Six Paths Sage, Hamura was virtually unknown throughout the ninja world. Yet his strength had never been inferior to Hagoromo's.
Seeing the remains of such an ancient being, even Hayashi felt a strange sense of reverence.
After all, this was an existence from thousands of years ago.
He sighed softly and climbed the steps one at a time, stopping several paces away from the coffin.
In a sense, Hamura was an ancestor of this body.
Hayashi naturally felt a degree of respect toward him.
Besides, he wasn't like Orochimaru, who would immediately start collecting samples the moment he encountered valuable research material.
This corpse had remained here for thousands of years. It had long since fossilized.
If there had still been flesh and blood, Hayashi might have taken a few strands of hair.
But in its current state, he doubted even a complete genome could be extracted.
More importantly, Himeji was outside inheriting the Ōtsutsuki legacy, while Hayashi himself had already obtained the complete Art of Yin-Yang Release.
His gains were already enormous.
Greed had its limits.
Asking for more would simply be shameless.
Still, Hayashi did not leave immediately.
Instead, he observed the crystal coffin from a distance.
Its material was extraordinary.
Even after thousands of years, it remained perfectly transparent without a single blemish.
It was obviously no ordinary object.
In today's ninja world, such material would undoubtedly qualify as an exceptional Ninja Tool.
After all, even ordinary possessions once used by the Six Paths Sage had become treasured artifacts among the great villages.
But Hayashi had no intention of taking it.
He liked maximizing his gains, but he wasn't that shameless.
What truly drew his attention was the symbol beneath the coffin.
A sun intersecting with a moon.
It resembled the powers of Yin and Yang that the Six Paths Sage had once bestowed upon Naruto and Sasuke.
"Should I..."
Just as Hayashi was considering his options, every hair on his body suddenly stood on end.
An overwhelming sense of danger washed over him.
Then, he heard it.
A faint, ethereal voice echoed through the silent tomb.
The problem was that, aside from himself, only Hamura's remains were here.
And skeletons did not speak.
Which meant...
"I am... Ōtsutsuki Kaguya... help... me."
Hayashi immediately turned around and ran.
Kaguya: "..."