Naruto: A Century as an Arrancar, Starting Off by Killing the Demi-God

"You can heal my legs?!"

Both Orochimaru and Nagato turned to him, their eyes filled with skepticism.

Uwa had previously mentioned to Deva Path Pain that he wasn't good at medical techniques. If he had been, he wouldn't have gone to such lengths to recruit Orochimaru in the first place.

Now he was saying he could heal them?

Nagato looked unconvinced, as if saying, "Don't try to fool me just because I didn't finish school!"

"Ahem, it's true," Uwa said, clearing his throat and speaking seriously. "Nagato, do I look like someone who would lie to you? I paid a high price to obtain this rare elixir. It can regenerate damaged flesh and restore the body. There's no doubt it will work."

As he spoke, he pulled out a small vial from his item storage.

The liquid inside was milky-white and viscous, not at all like a legitimate medicine.

Orochimaru narrowed his eyes suspiciously.

Uwa coughed again. "Ahem, I can run a chemical analysis to verify its components if that'll make you feel better…"

"No need," Nagato interrupted. "I trust you, Uwa-senpai."

He took the vial without hesitation, popped the cap, and drank the entire contents in one go.

Gulp gulp gulp!

The moment the medicine hit his stomach, Nagato's entire body began to tremble.

Within seconds, his eyes rolled back and white foam began to drip from his mouth.

Orochimaru watched, stunned. "Uwa, are you absolutely sure about this? What if some quack conned you into buying this? I don't care if Nagato's body collapses, but if those Rinnegan are damaged, we're in serious trouble."

"I… I think it's probably fine…" Uwa mumbled, visibly unsure as he watched Nagato's convulsions.

In the world of Soul Reapers, this was definitely meant to be taken orally. But he didn't recall anyone foaming at the mouth…

Wait, did something actually go wrong?!

Just as he stepped forward, worried and ready to intervene, the violent spasms suddenly ceased. Nagato's eyes returned to normal.

"It worked! It actually worked!"

Nagato's voice trembled with emotion as he looked down at his legs. "Uwa-senpai, my legs… they're healed!"

Overcome with excitement, he unstrapped his legs from the metallic restraints.

He began to walk slowly at first, stumbling a bit, but soon picking up pace.

Before long, he was striding confidently across the platform.

"Hahaha! I can walk again!"

He shouted with joy, running across the room like a child set free.

Half an hour later, Nagato finally returned to Uwa's side, eyes glistening with tears.

"Uwa-senpai, I-"

"No need to thank me," Uwa waved him off with a small smile. "Now let Orochimaru check your body and come up with a plan for how we'll restore your life force. You'll need that stability to wield the Rinnegan without side effects."

"Leave that to me," Orochimaru said with a nod.

The vast underground platform was filled with sophisticated instruments.

All of them had been acquired by Obito and Tobi, who'd posed as Root operatives a month ago.

Thanks to Obito's Kamui space, transporting equipment had been ridiculously easy.

Even Uwa's spatial jutsu couldn't compete with that level of convenience.

Following Orochimaru's instructions, Nagato underwent a full-body examination blood tests, urine samples, stool collection… the whole nine yards.

By the end, Nagato looked like a man suffering from severe constipation.

"So? Got anything?" Uwa asked.

"More than one option, actually," Orochimaru rasped, licking his lips thoughtfully. "The first approach is to transplant large quantities of White Zetsu cells. The downside is that it would require significant damage to Nagato's existing tissue, and without enough experimental data, I can't say how many organs we'd need to remove."

"Even though Nagato's a member of the Uzumaki clan, known for their vitality, the Rinnegan still puts too much strain on his body. I suspect even a full-body transplant of White Zetsu cells wouldn't be enough."

"What's the second method?" Uwa asked immediately.

"The second is to transplant Hashirama Senju's cells. But that brings intense rejection symptoms. If Nagato overuses his chakra, those cells could devour him from within. Danzo's right arm was one of my earlier experiments an inferior prototype," Orochimaru explained.

"Nope. Not even considering that one," Uwa said without hesitation.

In the original timeline…

During his fight with Sasuke, Danzo's chakra ran dry and the Hashirama cells began to devour him alive.

Dude almost turned into a literal tree.

Fortunately, Danzo had the presence of mind to sever his own arm.

But even then, he had to sacrifice himself to seal a bridge. What a way to go. (author's note: insert troll face)

"What's the third option?" Uwa asked.

"The third and final method," Orochimaru said, eyes gleaming, "is to transplant primitive Hashirama cells directly into Nagato. These cells devour other cells and rapidly multiply until they replace every cell in the body. But this method is extremely dangerous the success rate is abysmally low."

"How low are we talking?"

Orochimaru raised a finger. "After the First Hokage died, Wood Release vanished. The other great nations grew restless and threatened war. In desperation, Konoha threw everything they had into research."

"They began transplanting Hashirama cells into adult volunteers from the Senju clan. Every single attempt failed. Too many died. The village was forced to seal the jutsu and declare it forbidden."

"Later, I continued the research. I implanted Hashirama cells into sixty newborns. I assumed their cell activity would improve success rates. But even then, the rejection was too intense. One by one, they all died…"

"No," Uwa interrupted, shaking his head. "One child survived."

"That's impossible," Orochimaru frowned. "All sixty of those infants wait… are you talking about that last one? The failure I abandoned?"

"Yes. That boy had an unbreakable will to live. He survived against all odds. Danzo discovered him by chance and raised him in Root. His codename is Kinoe," Uwa explained.

"I see…" Orochimaru muttered.

"Now do you understand? The boy eventually awakened Wood Release. Now, he's no match for the First Hokage, but when it comes to construction work, he's a real asset."

Uwa was just about to make a jab at Yamato's watered-down Wood Release.

Before he could, Orochimaru suddenly clapped his hands, eyes gleaming with excitement.

"It's the will! That's the key to compatibility!"

"…Are we talking about the same thing here?" Uwa blinked.

"The key to surviving a Hashirama transplant has never been about cell activity. It's the subject's unwavering will to live!"

Orochimaru was practically dancing in place, visibly elated.

"The Senju volunteers were motivated by duty to the village. They accepted their fate as sacrifices. But that's just the will to die not the will to survive. Without that, they were doomed to fail!"

He paused, then frowned. "But if that's true… why was Kinoe's Wood Release so weak?"

"Good question," Uwa smiled, encouraging him to think deeper.

"It's bloodline and talent," Orochimaru muttered, his eyes turning bloodshot. "Willpower determines whether you survive the transplant. But talent and bloodline determine the ceiling of your Wood Release."

"Kinoe didn't inherit the Senju bloodline, and his talent was subpar. That's why his Wood Release was weak."

"But Nagato he has both exceptional talent and distant ties to the Senju lineage. If his willpower holds out, not only will his life force skyrocket, he could awaken a form of Wood Release nearly equivalent to the First Hokage himself!"

"And combined with the Rinnegan… Nagato would stand at the absolute summit of the shinobi world!"