Naraku Sora carefully observed their expressions.
To his surprise, Shihōin Chika remained entirely unmoved. He maintained a calm and composed demeanor from beginning to end, perfectly fitting his former identity as the Commander-in-Chief of the Onmitsukidō.
Zenjōji Uhin had been a bit excited at first, but after a few seconds of thought, he regained his composure and let out a heavy sigh.
Ōtogawa Furūki reacted similarly.
On the other hand, Saitō Furōfushi couldn't stay calm at all. Her eyes widened as she reached through the iron bars and shouted, "Kid, do you really have a way?"
Katori Batsu'unsai pursed her lips and said nothing, but she looked at Naraku Sora with a face full of expectation, seemingly waiting for him to continue.
Naraku Sora nodded. "There is definitely a way, but it still needs to be verified."
Hearing this, Saitō frowned. "What? I thought you could do it right now."
"Let me make this clear in advance. If it's a method that harms you or requires you to pay some sort of price, it's best not to bring it up."
"After all, we don't belong to this era."
Katori Batsu'unsai nodded and said earnestly, "We already owe you enough, Lord Naraku. We don't need you to sacrifice anything else for us."
Neither of them had a bashful personality; they spoke whatever came to mind.
Shihōin Chika was the same. He looked completely at ease, seemingly not taking Naraku Sora's previous words to heart.
"Kid, I know what you mean."
"In this era, I've seen many young people who are much stronger than we were back then. They are working hard to push the Soul Society forward."
"For example, that Mr. Urahara who always has dark circles under his eyes, and Mr. Kurotsuchi who looks gloomy and dangerous all day."
"The fields they excel in are different from ours—scientific research, forbidden domains..."
"Perhaps with the help of such talents, you really could help us restore our living bodies, but that's not what I want."
"I'm tired of my past life, and now it's time to part ways."
"Sometimes, death isn't the end, but the beginning of a new journey."
"I'm still looking forward to a future full of changes..."
Ōtogawa nodded and added, "Actually, when I first heard your words just now, I was quite excited."
"But thinking about it carefully, I feel it's unnecessary."
"In the current Soul Society, other than Lord Genryūsai and Senior Unohana, there is no one I am familiar with anymore."
"And the future belongs to you young people."
Zenjōji Uhin grinned, stopping just short of saying, "Me too."
"However, Furōfushi and Batsu'unsai are different from us."
"Those two are true geniuses who were thrust onto the battlefield to crusade against the Quincies before they could even enjoy life."
"They were sent packing to Hell before they could experience anything."
"So, if you really have a way, Lord Naraku, you might want to consider them first."
"As for us, we'll stick to what we said before."
At this point, the faces of the three men were filled with relief, showing not a hint of nostalgia for the present.
Naraku Sora raised an eyebrow.
To be honest, perhaps because he hadn't lived as long, he couldn't empathize with their feelings at all.
However, since this was the decision of Shihōin Chika and the others, he would choose to respect it.
"By the way, should we go say goodbye to Old Man Yama?" Chika seemed to suddenly think of something and turned to the two beside him.
"Let's go. If we leave without saying goodbye, Lord Genryūsai will be very sad."
"Huh? Does that god of slaughter even have such emotions? I remember he was the one who killed me back then, slicing off half my head with a single strike."
"..."
Watching the three men joke around, Katori Batsu'unsai frowned beside them, seemingly beginning to hesitate about her own choice.
Saitō Furōfushi, on the other hand, was completely unaffected. She just clamored for Naraku Sora to open the cell door so she could go out and ruthlessly beat up Komamura Sajin and the others.
*As a senior, one must mercilessly bully their juniors!*
Shihōin Chika and the others left Shino Prison and headed to Squad 1 to bid farewell to Yamamoto, while Naraku Sora quietly slipped away to Squad 5.
Familiar with the route, he avoided the patrolling squad members and headed straight for the lieutenant's independent courtyard.
"Sōsuke, hurry up and help me."
Under Aizen's astonished gaze, Naraku Sora detailed the Rinne Tensei Technique he had painstakingly comprehended.
This was originally an exclusive forbidden jutsu belonging only to Rinnegan possessors. Now, after being localized and improved by his peerless wisdom, it had become a type of Kidō.
Because its effects were so heaven-defying, it could easily be classified as Ura Kidō.
Naraku Sora had once seen Ichibē Hyōsube cast Ura Kidō. He could only say that its power was absolutely astonishing, and its operational logic seemed fundamentally different from the Kidō system of the Soul Society.
He had later specifically asked Tenjirō Kirinji about it, and the answer he received was that only the Zero Division could learn and master Ura Kidō.
Other Soul Reapers, lacking the Oken constructed from the Spirit King's power, wouldn't be able to cast it even if they learned it.
Listening to Naraku Sora's description, Aizen didn't pay much attention at first. But as the in-depth explanation of Rinne Tensei continued, a clear look of surprise appeared on his face.
"A forbidden Kidō that reverses life and death?"
"And you're telling me you comprehended this by accident?"
Naraku Sora nodded with an honest expression.
Looking at this guy's face, Aizen suddenly felt the urge to let his blood pressure spike.
Although he didn't know exactly how Sora had comprehended it, he knew Naraku Sora very well.
Judging from his expression, this guy wasn't fooling him.
But the more this was true, the more unbelievable it was.
They had known each other for so long, yet Naraku Sora could still pull out something novel.
From Hollowfication to Reishi convergence, from Spirit King candidate to a heaven-defying Bankai, from high-sequence Kidō to self-created Kidō.
Was there anything this guy couldn't do?
Aizen thought carefully.
It seemed he was completely clueless when it came to the field of science?
He shouted about peerless wisdom all day long, but in the end, he couldn't even understand the simplest, most basic Hōgyoku formulas, relying entirely on rote memorization.
*Could it be that the more a person lacks something, the more they emphasize it?*
Aizen raised his eyes and glanced at a certain someone. Naraku Sora grinned, revealing two rows of neat white teeth.
He shook his head, choosing not to dwell on this any longer.
"I have a general understanding of the situation."
"The reason you didn't immediately use Rinne Tensei on Katori Batsu'unsai and the others is that you aren't sure about the potential side effects this Kidō might produce."
"So you wanted me to help you research and reference it."
Naraku Sora smiled. "The one who knows me best is Sōsuke."
Aizen felt somewhat gratified by this.
This guy was much more cautious than before. At the very least, he wasn't reckless enough to experiment directly.
"Let's go to the Department of Research and Development."
"Urahara Kisuke and Kurotsuchi Mayuri also have extraordinary talent in Kidō. In some areas, they might be able to offer appropriate suggestions."
The two left Squad 5 and arrived at the Department of Research and Development.
Inside the laboratory, after listening to Aizen's explanation, Urahara Kisuke looked at the innocent-faced Sora and couldn't help but twitch his eye.
He no longer doubted Naraku Sora's species.
Anything was possible, but he definitely wasn't a normal Soul Reaper.
Independently comprehending such a heaven-defying Kidō was simply impossible for a Soul Reaper.
He seriously suspected this reckless brute was the illegitimate son of the Spirit King.
Or at the very least, the illegitimate son of the Monk Who Calls the Real Name, Ichibē Hyōsube.
Soon, with Kurotsuchi Mayuri's assistance, Naraku Sora successfully wrote down all the key points and details of Rinne Tensei.
The dense handwriting completely filled seventeen A4 pages.
Its complexity made even Aizen sigh with emotion.
This was the most complex Kidō he had ever seen in his life.
Let alone learning it, an ordinary Soul Reaper would probably have to spend decades or even centuries just to understand it.
Looking at the complicated text, Urahara Kisuke wanted to cry but had no tears.
This bastard didn't treat his subordinates like human beings at all. Analyzing a Kidō of this level would make all his hair fall out.
Not to mention, he currently had the task of researching Hell.
This was an assignment handed down by Head Captain Yamamoto, and he didn't dare slack off in the slightest.
*Both master and disciple are absolute monsters!*
*Genryū? Bah!*
Although he grumbled internally, the work still had to be done. Otherwise, who knew where that massive fist would land.
The three of them quickly got into the zone.
Data was continuously entered into the equipment, and things Naraku Sora couldn't understand at all began scrolling across the screens.
Even though Rinne Tensei was a Kidō he had comprehended himself, after being analyzed by the three of them, it turned into completely unfamiliar knowledge.
Just looking at it gave him the illusion that his scalp was itching.
It felt as if something was about to grow out of his brain.
Fortunately, they didn't need to learn Rinne Tensei; they only needed to analyze whether there were any side effects.
The task was relatively simpler.
Yet even so, it still took several days to completely finish.
Aizen looked at the data flashing across the screen and frowned slightly.
"Does such a powerful Kidō merely consume spiritual power?"
"I feel like something isn't right..."
Urahara Kisuke had the same expression.
Completely resurrecting the dead was too horrifying. In his understanding, this was challenging the authority of the gods, far more outrageous than any other research.
Just as the two were conflicted, Kurotsuchi Mayuri stretched his mouth into a very terrifying smile.
"It indeed consumes spiritual power, but the amount might be far greater than you anticipated."
"If my calculations are correct, completely resurrecting a Soul Reaper requires exhausting all of the caster's spiritual power."
Aizen's gaze darkened.
Because the three of them had divided the work, there would be differences in their analyzed results.
But he had never doubted Kurotsuchi Mayuri's abilities from beginning to end.
This was a genius scientist who was not the slightest bit inferior to him and Urahara Kisuke.
"Doesn't that equate to trading a life for a life?"
Urahara Kisuke shook his head. "Other than Lord Naraku, it's impossible for anyone else to learn this Kidō."
"Trading Lord Naraku's life for the lives of the first-generation captains."
"The price is a bit too steep."
Kurotsuchi Mayuri curled his lips in disdain and mocked, "Although I know you're worried about Lord Naraku, could you wipe that smile off your face when you say that?"
"Am I smiling?"
Urahara Kisuke reached up and touched his face.
*Indeed, he was grinning from ear to ear.*
Aizen ignored the two bantering with each other. He calmly organized the research results, preparing to stop a certain someone's foolish behavior.
"Since that's the case, let the dead go where they belong."
"Wait, Mr. Aizen."
Kurotsuchi Mayuri spread his hands, his smile carrying a bit of confidence.
"What if I told you there's a way to resolve the side effects?"
"?"