Before long, Ryou was holding a child-sized scroll, reading it with great interest.
This was the Uchiha Clan's Fire Release archives, likely taken by Madara when he left; it contained many high-level Fire Release Ninjutsu.
The elemental Ninjutsu Ryou knew were all C-rank introductory techniques, such as Fire Release: Great Fireball Technique, Phoenix Sage Fire Technique, and the Small Fireball Technique.
As for Lightning Release, he knew Earth Flash.
Other basic techniques like the Clone Jutsu and Transformation Jutsu weren't even worth mentioning.
Ryou looked at a Fire Release technique called Great Fire Annihilation. This was Madara's signature Fire Release; in his hands, a B-rank Ninjutsu was released with the power of a forbidden jutsu.
Just as Ryou finished memorizing Great Fire Annihilation, Black Zetsu took the Uchiha Clan Fire Release scroll away.
"What are you doing? What are you doing?"
Black Zetsu's voice lacked even a hint of emotion: "You still need to develop a rejuvenation technique for Lord Madara. Don't waste all your time on Ninjutsu."
He had to meet today's performance quota first, or else he'd be electrocuted.
Helpless, Ryou looked at Ryūzetsu, who was curled up in a corner, looking somewhat lost.
Although Ryūzetsu was the same age as Itachi, Itachi was a Ninja who had been to the battlefield and seen blood.
For a young girl like Ryūzetsu to be captured and brought to this dark, terrifying underground space without crying showed that her mental fortitude was already up to standard.
Ryou walked over: "Ryūzetsu, tell me about your Dragon Life Reincarnation technique."
"..."
Ryūzetsu glanced at Ryou and remained silent.
Ryou put on a fierce expression and took off his rogue ninja headband to show her: "Hmph! See this? This is a rogue ninja headband."
"I am Konoha's SSS-rank rogue ninja, the ultimate killer, Uchiha Ryou."
Ryūzetsu looked at Ryou's headband. From up close, the scratch on the headband looked like it had been drawn on, and the color was even fading.
Ryou noticed this small flaw too and pulled out a pen to redraw it.
He put it back on: "Back in the day, I held a kitchen knife in each hand and hacked my way from the Konoha gate all the way to the Hokage's Office. I hacked back and forth for three days and three nights; it was a river of blood!"
"But I just kept swinging, my hands never stopping, and I didn't even blink once!"
Ryūzetsu wondered if his eyes would get dry from not blinking for so long.
Although she had just become a Ninja, she knew that the highest rank for a rogue ninja was S-rank; there was no such thing as SSS-rank.
Ryou threatened: "If you know what's good for you, hand over your forbidden jutsu, or I'll slaughter your entire Village!"
"..."
Ryūzetsu remained silent, staring intently at the ground.
Kusagakure might be small, but it was as resilient as grass; Ryūzetsu's teacher had taught her that lesson.
Tobi was tired of hitting him, so Obito could finally catch his breath. But he forced himself to stand up and cursed at Ryou: "You bastard Ryou, threatening such a small child, are you even human?"
Ryou ignored Obito. Seeing that Ryūzetsu wasn't intimidated, he sneered: "A tough nut to crack, I see."
"Hmph, it seems Kusagakure is such a small Village that you haven't heard of the terror of Ryou."
"The Sage of Six Paths was born a thousand years before me, was he afraid of me, or was it a case of 'two kings never meeting'?"
"Hashirama and Uchiha Madara were born before me, was it the 'clumsy bird flying first,' or were they avoiding my brilliance?"
As Ryou spoke, he specifically glanced back. Seeing that Madara was sleeping like an incompetent husband, he felt relieved.
"When I close my eyes, the world goes dark; when I open them, it's dawn. Ryūzetsu, I ask you, are you afraid?"
「・_・?」
Black and White Zetsu, standing beside Madara, were stunned by Ryou's eccentric behavior.
White Zetsu asked the more cultured Black Zetsu: "What is he doing?"
Black Zetsu was also puzzled: "I don't know! Scaring a kid, I guess?"
Unable to scare Ryūzetsu, Ryou directly hugged her leg and began to beg: "Please, Ryūzetsu, teach me your forbidden jutsu quickly, or we're all going to die."
Ryūzetsu finally reacted: "No, I can't teach you. This is the Village's forbidden jutsu. My teacher told me not to pass it on to anyone else."
Ryou grabbed Obito, and Lightning Release Chakra condensed in his hand, immediately making Obito howl in pain from the shock.
"Ryou, You... $%#..."
"Ryūzetsu, see that! I said I kill without blinking, did you think I was joking with you?"
She was just a little girl, after all, and hadn't completed the full systematic training of a Ninja.
Ryūzetsu was a bit frightened by the way Obito was being tortured, retreating a few steps as she said: "But... my forbidden jutsu is a Kekkei Genkai. My teacher said only I can learn it."
Ryou barked: "I don't care, teach it to me first!"
"O-okay..."
A short while later, Ryou heard the principles of Dragon Life Reincarnation from Ryūzetsu's mouth.
This move was indeed a forbidden jutsu for Kekkei Genkai users. If Ryou wanted to learn it, he would first have to develop the Chimera Technique to version 2.0 and steal Ryūzetsu's Kekkei Genkai.
But this move involved using one's own life to revive a person on the brink of death. He wasn't stupid; why would he give up a precious slot in his Chimera Technique for Dragon Life Reincarnation?
But if he didn't restore Madara's youth, he would die.
While he couldn't learn Dragon Life Reincarnation directly, Ryou could use it as a reference! Dragon Life Reincarnation was a high-level nature transformation of Yang Release.
Life-based Secret Techniques were all nature transformations of Yang Release. Tsunade's Creation Rebirth and Chiyo's One's Own Life Reincarnation were both Yang nature transformations of Chakra.
Ryou's Plunder Rebirth was also Yang Release.
Ryou had previously fused with White Zetsu cells, and his application of Yang Release was becoming increasingly proficient.
With his familiarity with his own forbidden jutsu and the reference from Ryūzetsu's Dragon Life Reincarnation, Ryou could probably develop a 'transferable' version of Plunder Rebirth in two or three weeks.
But doing it too fast wouldn't work. He had to master several high-level Fire Release techniques as soon as possible and get thoroughly familiar with his White Zetsu cells, striving to increase his strength before Madara returned to his peak.
With this plan in mind, Ryou asked Zetsu to get him paper and pen; he was going to start calculating and designing Plunder Rebirth 2.0.
Version 1.0 of Plunder Rebirth focused on absorption; version 2.0 would specialize in release.
That is, giving his own life to someone else, and then absorbing the life of another person himself.
It sounded simple, but overcoming the technical challenges wasn't that easy, much like nuclear fission and nuclear fusion—the splitting and joining of atoms.
But the technical advantage of the former led the latter by over 70 years... Orochimaru was moving towards the Land of Grass with the Reanimated Hiruko.
On the way, Hiruko had already been threatened by Orochimaru into revealing the Chimera Technique.
Version 1.0 of the Chimera Technique could only accommodate one Kekkei Genkai, which didn't mean much to Orochimaru.
Orochimaru was also at a '1.0' stage; he hadn't yet become a complete advocate of bloodline theories, nor had he witnessed the ultimate power of the Mangekyo and Wood Release.
He was still arrogant and self-satisfied with power at the level of the Sannin.
At Orochimaru's level, many Kekkei Genkai users weren't even fit to carry his shoes.
The heads of the Senju, Uchiha, and Hyuga clans in the Village would all be respectful and subservient upon meeting Orochimaru.
Mastering a single Kekkei Genkai was not worth mentioning to Orochimaru.
What Orochimaru truly valued was Plunder Rebirth, which was derived from the Chimera Technique, Ryou's technique for immortality.
Orochimaru had also developed Living Corpse Reincarnation, but it had many limitations.
It had a long cooldown time and required considering the compatibility between the host body and the soul.
Furthermore, he had to bear the soul damage during the reincarnation process and the risk of easy backlash.
It was far inferior to the simple and crude nature of Ryou's forbidden jutsu. Cooldowns? Compatibility? He didn't understand any of that; he just grabbed a living person and refined them instantly.
This was the perfect immortality suited for Orochimaru.