As Orochimaru's final words faded into the wind, Ren Uchiha's serpentine pupils constricted.
Pure natural energy... can be used directly?
But how was that possible? For a human shinobi to master Senjutsu, the only established path was to achieve a perfect trinity of Physical Energy, Mental Energy, and Natural Energy to refine Senjutsu Chakra—and thus enter Sage Mode.
This was a fundamental law of the shinobi world, etched into the very foundations of Ninjutsu.
Under such ironclad rules, Orochimaru was telling him that even this could be broken? But how?
Ren ground his teeth, his gaze shifting to the wall of snakes above him. It groaned and shuddered under the relentless bombardment of wind blades, the sound of impact echoing like a hammer on an anvil. It was clear this barrier wouldn't hold for long.
His mind raced at a frantic speed, desperately scouring his memories of the manga and anime from his previous life. He searched for an answer, a hint, a hidden mechanic—but nothing came to mind.
Then, Orochimaru's parting words echoed in his soul once more.
'Follow your body—and find the answer.'
Those words acted like a beacon of light in the darkness. Ren snapped his head up.
He suddenly remembered the very beginning. When Orochimaru had first bitten him, injecting the Cursed Seal of Heaven... how had he survived? Back then, he had neither consciousness nor chakra; his situation had been far worse than it was now. How had he consumed the violent natural energy flooding his veins then?
Ren's eyes widened as he looked at his own broken body. If there was a technique capable of taming such savage, raw power, then it could only be—
Forbidden Jutsu: Body Incarnation!
The technique that burned life force itself, and could even use the power of a Tailed Beast as a substitute fuel!
In that moment, a door to a new world swung open for Ren. Using his Sharingan, he focused intently on the violent, surging natural energy of Ryuchi Cave that was currently twisting his flesh and bones.
He took a sharp breath, held it, and forcefully activated Body Incarnation.
In a flash, the jagged black markings that had covered half his body—and were threatening to consume him entirely—began to writhe and contort.
Then, they retreated.
The markings shrank back, receding toward his neck. The raw, violent natural energy was intercepted by the Forbidden Jutsu, captured, and thrown into the furnace of his life force to be refined into a brand-new power!
Like a roaring diesel engine, the process began:
Grind. Impact. Ignite. Compress. Explode!
BOOM!
Ren's heart began to beat at a rhythm far beyond that of a normal human. Hot blood surged through his veins, and a relentless tide of vitality erupted like spring bamboo after a rain, beginning the rapid repair of his exhausted body.
Wounds closed. Flesh was revitalized. A steady stream of his own chakra was refined and immediately fed back into the Body Incarnation cycle.
Ren surged upward, pushed by the sheer pressure of his erupting chakra until he stood straight once more. His severed right arm began to sprout flesh and bone with a terrifying speed, reconstructing itself up to the elbow in a mere blink of an eye.
But that seemed to be the limit. The black markings of the Cursed Seal had fully retreated to his neck, returning to their original "Cursed Flower" form. Even the serpentine mutations on his body began to fade.
The Cursed Seal was still drawing natural energy from the air to serve as fuel, but the speed had noticeably slowed down.
"Not enough... it's not nearly enough!"
Ren gripped his incandescent blade, staring at the chakra flow within him while gritting his teeth.
Refining the Cursed Seal's power provided the chakra needed to maintain the Forbidden Jutsu and heal himself, but it was also forcing his body back into its normal human state. At this critical junction, Ren didn't just need high-speed regeneration.
He needed combat power.
Even if he had to become a demonic serpent—even if he had to pay a massive price for those inhuman abilities like infrared sensing, scale armor, and serpentine speed—it would be worth it!
He couldn't let Ebizo escape. If that old man got away, then the sacrifices of Shinichi Uchiha, Shisui, Akichi, Otsu, and Ryuma Aburame would all be for nothing!
However...
As if in response to the desperate wish in Ren's heart, the Cursed Seal on his neck suddenly flared with light!
The world spun.
When Ren opened his eyes again, he found himself within a deep, cavernous snake den. In the distance, the rhythmic thrum of a wooden fish drum echoed through the gloom. Through the heavy darkness, he could make out the silhouette of a temple so vast its boundaries were lost to the horizon.
Suddenly, a colossal, jade-green snake—whose head alone was large enough to crush the cavern walls—slithered out of the dark.
As Ren watched in bewilderment, the snake's massive body writhed and shifted, transforming before his eyes into a beautiful young woman.
She wore a long white robe and a golden crown topped with a shimmering orb. She possessed a dignity and grace that felt like pure jade. Ren blinked, unsure of what was happening, when the woman's voice—cool yet solemn—rang out.
"The new summoner of Ryuchi Cave!"
"Do you wish to obtain power that transcends humanity—power that transcends all?!"
Ren looked up at the woman, realization dawning on him. Tagitsuhime? One of the high-ranking guardians of Ryuchi Cave and a direct confidante of the White Snake Sage.
Was he reverse-summoned? Or was he caught in her illusion that could turn a barren wasteland into a Ryuchi Cave castle? And what was going on with this Cursed Seal? For Sasuke, it was a power-up tool, but for Ren, it felt like it had turned into a passive "Summon Assistance" skill.
But hearing her question, Ren didn't hesitate for a single second. He looked at her with an urgent, sharp gaze.
"Give it to me!"
"I don't care about the risks! If it's power, give it all to me!"
Tagitsuhime stared at the youth. Her gentle eyes suddenly shifted into vertical, golden snake pupils, locking onto Ren's Sharingan—which, despite the Cursed Seal receding, still maintained its serpentine slit form.
A flicker of shock crossed her face. Someone who can perfectly integrate natural energy within a human body...
In thousands of years, such a feat was unheard of. Recalling the White Snake Sage's orders, Tagitsuhime suppressed her inner tremors and slowly produced a green cat's eye stone from her robes.
She narrowed her eyes, her tongue flickering out to lick her lips with a hiss. Her youthful disguise shifted, revealing the true form of a Ryuchi Cave serpent beneath. Her nose flattened, and her mouth split into a gaping, blood-red maw.
In the boundless darkness, she stared at Ren and let out a cold, chilling laugh.
"Heh... heh... heh..."
"Then come and take it."
She held up the green stone, which emitted a haunting green glow in the dark. Then, her emotionless voice thundered through the depths of Ryuchi Cave:
"You have only one chance, human—"
"Either become a Sage of Ryuchi Cave,"
"Or die!"