This ninjutsu could be considered a groundbreaking achievement in Tsunade's research.
However, it came with significant limitations.
First, it required a chakra comparable to that of a Tailed Beast.
Second, the user needed to be proficient in sealing techniques.
Once these two prerequisites were met, the user would wait until the end of their natural lifespan.
Then, by embedding seals into their body and finding a safe place to wait until their Tailed Beast-level chakra was completely exhausted, they could achieve resurrection through the Rebirth from Death Technique.
This process would take a long time—possibly even several years.
The body would return to its peak condition, though all chakras would be depleted.
Moreover, since the technique was still incomplete, its actual success rate was uncertain.
Jiraiya marveled at the contents of the scroll.
"If other elderly ninjas learned of this technique, they would spare no effort to obtain it."
Although most of Konoha's older generation had perished during the Second Shinobi World War, a handful of ancient figures still survived.
They would fight tooth and nail for this technique—it was essentially a second life.
"That's why only the three of us know about it for now."
Despite her reservations about the moral character of these two perverts—one old, one young—Tsunade still trusted them enough to share the secret. She hadn't even dared to tell Orochimaru.
Orochimaru's demeanor had grown increasingly sinister lately, and he had casually mentioned his pursuit of immortality.
Kin glanced around thoughtfully.
"What are you looking at?" Tsunade asked, puzzled.
Kin shook his head. He was merely wary that this technique might attract the attention of Uchiha Madara.
That old monster was still lurking in the shadows.
Tsunade didn't press further. Instead, she said to Kin,
"As the department head, you have the authority to decide what happens to this."
Everything produced by the Research Department ultimately belonged to Kin.
"Lady Tsunade, the decision is yours."
Kin declined. Given the technique's severe drawbacks, he wouldn't use it unless he was on the verge of death.
Nor did he care who else might obtain it.
After all, he already had it.
"Then I'll seal it away for now."
Tsunade nodded. She had no intention of releasing the technique, as it could plunge the shinobi world into chaos.
Konoha, in particular, had the highest number of elderly ninjas.
Though her research on transcending life and death was no less disruptive.
If perfected, it could rewrite the rules of the entire shinobi world.
This technique was merely an accidental byproduct of her studies, not something she valued highly.
Yet, through it, she had touched upon the boundary between life and death.
And the reason she had reached this point—
Tsunade glanced at Kin.
It was all thanks to the materials he had provided.
Just how many treasures were hidden in that mind of his?
She almost wanted to crack it open and see.
None of the three noticed the white figure lurking deep underground, eavesdropping on their conversation.
It muttered to itself,
"After resurrection... can they still poop?"
Kirigakure.
Uchiha Madara studied the contents of the technique in his hand.
"Tsunade, Hashirama's granddaughter... she has talent."
The Rebirth from Death Technique was now in his possession.
As he read through it, he realized this life-and-death reversal technique seemed tailor-made for him.
However, the success rate was far from guaranteed, so Madara wouldn't risk using it unless necessary.
"Madara, will you use this technique?"
Black Zetsu, attached to a White Zetsu, asked.
If Madara could resurrect himself with this technique, the plan to free Kaguya could be accelerated.
"No rush."
Madara shook his head.
Not only was the technique incomplete, but resurrection would also leave him in a weakened state.
If he were to use it, he would wait until it was fully perfected.
"Uchiha Kin... you continue to surprise me."
Without Konoha's Research Department, this technique would never have been born.
"We'll keep waiting."
Until his successor appeared.
Until his life reached its end.
He would bring the world...
Eternal peace.
Nightfall.
Kin sat cross-legged in his underground research lab.
His mind processed the memories of all his shadow clones.
Aside from the flesh clone in the Land of Rain, he had dispelled all research clones in an instant.
It was time to refine the Heavenly Demon Art once more.
The shinobi world's advancements in chakra technology had been steady, and they provided some inspiration for him.
Kumogakure and Iwagakure's improvements to the Basic Internal Energy Technique had nearly elevated it to the level of Chakra Internal Energy.
Though progress was slow due to a lack of direction and methodology, their creative ideas gave Kin plenty to work with.
In terms of ninjutsu development, setting aside the "Golden Finger" ability—
Kin stood at the pinnacle of the pyramid.
Below him were Orochimaru and Tsunade.
The rest of the shinobi world occupied the third tier. To develop the techniques Kin needed, the entire world would need to advance to the second tier.
This new version of the Heavenly Demon Art was entirely Kin's own creation.
"Fusing techniques into techniques."
This was Kin's approach. His combat style had always relied on the Dark Walker Technique to conceal his Wood Release, Flying Thunder God, and Shadow Imitation techniques.
A single technique actually encompassed four different methods.
But this created delays in battle.
His solution was to integrate these techniques into the Dark Walker Technique itself.
It wouldn't drastically increase his power, but it would eliminate his vulnerabilities.
This was what his shadow clones had been researching.
And now, they had succeeded.
"First, the Shadow Imitation Technique."
Within the chakra pathways of Kin's Chakra Internal Energy, the Dark Walker Technique's routes subtly shifted, growing more intricate.
The Shadow Imitation Technique was successfully integrated.
From now on, the Dark Walker Technique would inherently include the effects of Shadow Imitation, eliminating any delay—a critical flaw in combat.
"Next, the Flying Thunder God Technique."
Flying Thunder God was far more complex than Shadow Imitation, but its deep ties to sealing techniques made the process slightly easier.
Soon, the Dark Walker Technique's pathways became even more elaborate.
Beads of sweat formed on Kin's forehead.
Altering these pathways felt like plucking at the tendons of his body.
Two techniques remained.
"Integrate the Six Treasuries Immortal Thief."
"Integrate the Soul Illumination Technique."
Veins bulged on Kin's face. These techniques were inherently complex, and adjusting them required painstaking effort.
The biggest challenge was the Six Treasuries Immortal Thief, a Yang-based technique that clashed violently with the Yin-based Dark Walker Technique.
Yin and Yang chakras are intertwined, repelling and coiling around each other.
Kin's entire body began to tremble.
His vision darkened, and dizziness threatened to overwhelm him.
If he passed out now, all his efforts would be wasted.
He stabbed a kunai into his thigh, using the pain to stay conscious.
The opposing Yin and Yang energies slowly merged.
Finally—
Kin let out a slow exhale.
He raised his arm, now as dark as the night sky.
"A Yin-Yang dual-nature Kekkei Genkai."
"The Heavenly Demon Art."
Kin stood up, and the bright lights around him seemed to dim in his presence.
"Success."
(End of Chapter)