Orochimaru

The cold, damp underground passage was permeated with the scent of preservatives and the distinct, musky odor of serpents. Uchiha Sakuya moved like a phantom, walking silently through this labyrinth belonging to the mad scientist. His Eighty Gods Mirror had long since seen through every mechanism, trap, and illusionary disguise, precisely guiding him toward the laboratory in the deepest reaches.

The laboratory door slid open automatically, as if it had long anticipated his arrival.

The room was filled with various containers holding specimens and complex instruments. A pale-skinned figure with long, disheveled hair stood with his back to the door, focused on concocting a purple reagent, his long tongue subconsciously licking the corner of his mouth.

"An uninvited guest... how rare." Orochimaru's voice was hoarse and magnetic. He did not turn around, seemingly unsurprised by Sakuya's arrival. "And, you come bearing such... interesting eyes."

Sakuya stopped, his gaze beneath the bandages sweeping coldly across the laboratory before finally landing on Orochimaru's back. "You knew I would come."

"Hehehe..." Orochimaru let out a low laugh and slowly turned around. Those golden snake-like pupils examined Sakuya with keen interest, especially the eyes that emitted an extraordinary aura even while hidden. "An orphan of the Uchiha clan, possessing a Mangekyo form that even I have never seen, causing such a stir in the ninja world recently... how could I not sense such a research subject delivering himself to my doorstep?"

His gaze was greedy and burning, as if he were looking at a perfect work of art.

"I need your knowledge." Sakuya went straight to the point, skipping any pleasantries.

"Oh? That is hardly the attitude of someone asking for a favor." Orochimaru smiled playfully. "And why should I help someone who might bring me immense trouble? Konoha has been watching me quite closely, after all."

"Because you cannot refuse." Sakuya's voice remained flat. "You crave knowledge, you crave to explore the ultimate secrets of ninjutsu, and you crave to transcend the cycle of life and death. And I can provide you with unprecedented 'materials' and 'possibilities'."

He raised his hand slightly, chakra flowing at his fingertips. "For instance, this..."

The next moment, to Orochimaru's astonishment, another "Orochimaru" slowly condensed from the shadows beside Sakuya! Whether it was his appearance, his aura, or even the subtle fluctuations of his chakra, he was almost identical to the original!

"Is this... the ability of the Eighty Gods Mirror? To be able to replicate to such a degree!" Orochimaru's golden pupils flared with extreme excitement and a desire to study. "To even simulate my own cellular information and chakra frequency... incredible! Simply incredible!"

Sakuya manipulated the Wood Release clone (which combined replicated cellular technology with the essence of illusion), and the "fake Orochimaru" even mimicked the original's demeanor, letting out a hoarse laugh.

"A perfect 'substitute' that can attract all attention and bear all risks for you," Sakuya said calmly. "And the real you can escape Konoha's surveillance and head to an absolutely safe place to study everything you desire to your heart's content. There, you will find a complete copy of the Book of Sealing, the latest data on the Tailed Beasts, and even... cell samples of 'Him'."

Every condition he threw out struck precisely at Orochimaru's greatest desires: a free research environment, top-tier research materials, and the opportunity to shake off surveillance.

The playfulness on Orochimaru's face was gradually replaced by a genuine, fanatical interest. He looked at Sakuya as if he were looking at an endless treasure trove.

"Truly... an offer one cannot refuse." Orochimaru's long tongue licked his lips again. "Then, what is the price? What do you need me to do for you?"

"Tailed Beasts." Sakuya spat out the two words. "I need the power of the Tailed Beasts. But not in a way that requires killing the Jinchuriki."

He stared at Orochimaru and stated his ultimate goal: "I want you to find, or rather, develop a method—a technique capable of separating the Tailed Beast from within a Jinchuriki completely, or at least extracting the vast majority of its power and chakra, without taking the host's life."

Orochimaru's golden pupils narrowed slightly. "Oh? That is an interesting topic. To seize a symbiont without killing the host... this involves life energy, soul contracts, and the ultimate reversal of sealing techniques... it is highly challenging." His eyes flashed with excitement; this was undoubtedly a problem that could satisfy his desire for research to the fullest.

"You can do it." Sakuya's tone carried an unquestionable certainty. "You are the only one who might be able to."

"Hehehe... I am held in such high regard, it seems." Orochimaru laughed. "It appears I have no reason to refuse. Then, happy to be working with you, Uchiha Sakuya-kun."

"Follow me." Sakuya turned around.

He left the "fake Orochimaru" in the laboratory to create the illusion of continued research. Meanwhile, the real Orochimaru, filled with irrepressible curiosity and excitement, followed Sakuya and vanished instantly through a pre-prepared space-time technique (derived from Obito or replicated and improved).

The next moment, they appeared in a more secretive, massive underground base that combined technology with sealing techniques—the very stronghold of Sakuya and Obito.

Orochimaru greedily breathed in the air here, which was filled with the scents of various powerful and rare energies, his golden pupils brimming with delight.

"Then, let us begin work." Sakuya's cold voice echoed through the empty hall. "I need an answer as soon as possible. As for the materials..."

His gaze swept toward a direction deep within the base that was heavily sealed.

"...they will be here soon." He was referring to the temporarily sealed Nadeshiko Haku, who carried the Three-Tails' chakra, and the Seven-Tails Jinchuriki, Fu, whose condition had already stabilized.

A dangerous transaction and partnership, concerning the fate of the Tailed Beasts and their Jinchuriki, was officially reached in this hidden corner. The mad scientist of the ninja world and the true ghost of vengeance had come together for the sake of their respective goals.