_________ POV Narration_________

After training for a few days, Ken ended up reaching a point where he truly didn't know what else to improve...

His swordsmanship was stagnant, it was unlikely to grow much without some actual 'stimulation' in real fights to the death.

His chakra levels were already as large as he could make them, his young age didn't allow for a lot more than that.

He could keep at it, training his already overtrained body further, hoping to see some results in the long term... But Ken simply felt that he was wasting his time.

After all, he had no guarantee of results down the line. He was already in the best possible shape for an assassin, all he needed was to grow and keep active.

He could try to learn a few more Jutsu, but he didn't really have anything that would be able to help him against the likes of Gyūki and the Raikage, so that would also turn out to be a waste of time...

In the end, he decided to focus on his transformation. After all, it was his trump card. It gave him speed similar to that of A, and it was also the only way he could see himself fighting the Raikage.

But how would he go about developing his transformation anyway? He lacked a basic understanding of what he even was. 

He did know how his body worked though, and he knew how the Scaled Sage Mode manifested itself and under what conditions...

The conditions were: he needed to be out of chakra... Mostly out of chakra anyway.

The point was that the balance between chakra and Nature Energy within his body needed to be tilted towards Nature Energy. If he ran out of Chakra completely he would turn into a statue.

Besides that, he also had a self-made condition... Which was to not attempt to use any Jutsu while in that form.

After all, if he ran out of chakra completely, he'd be left helpless against his enemy. So he needed to balance things perfectly.

Nothing he wasn't used to though... But the entire Scaled Sage Mode felt imperfect to Ken... Impractical even.

Ken was one of the few people that could fight while paying that much attention to the balance between the energies within his body.

Unbeknownst to him, that was the exact reason why so many people had a difficult time becoming sages, and why there were so few of them in the world.

It took quite a bit of concentration especially for Ken, as it was made even worse by the fact that Chakra was being constantly replenished with time.

Meaning that, if Ken wanted to stay in that form he'd have to expel it constantly in order to maintain the supremacy of Nature Energy within his body.

'Is there any way to stop chakra from flowing into my body...?'

In the end, the Blind Assassin ended up asking his retainers.

Akira, the now immortal Third Blade, wasn't able to give him any answer, as he didn't have any formal training as a shinobi.

Tosho, the first blade, did help Ken understand a few more things about the human body. Like the way chakra flowed and that it travelled through different channels throughout the body.

He also remembered to tell Ken about the points where Chakra could leave the body... But even he wasn't able to give many specifics, as his days learning about the basics were long behind him...

In the end, Ken ended up in Saburo's laboratory.

The Second Blade was able to give him a much more thorough explanation of the human body and the chakra network, even drawing an illustration by hand, leaving deep imprints on the paper and allowing Ken to 'read' it.

"Chakra travels through us in these channels, as I'm sure you already know. But it's quite self-contained..."

Ken nodded as he felt the diagram that Saburo had drawn for him. It all made sense, he was able to build an image of the chakra network that was drawn on the paper.

But he also knew that Chakra wasn't just continued within one's body... After all, if that was the case then Shinobi wouldn't be able to practice their jutsu.

"Chakra comes out of the body through various specific points located at key spots throughout the body. These special points are called Tenketsu/Pressure Points, and there are 361 of them in the human body.

They are very small, unseen to the naked eye. About the same size as the tip of a needle."

Saburo filled the diagram of the Chakra network that he had drawn with dots, his hands moved fast as he spoke confidently.

It was clear that he knew the human body by heart, he answered so quickly that it felt as if he didn't even need to think about it.

Ken nodded when hearing that, it was the first time he received such in-depth knowledge about Chakra networks...

"Interesting..." The masked assassin said as he rubbed his chin while feeling the points laid on paper with his other palm.

"Is there any way to stop chakra from flowing to a specific part of the body?"

"... Yes. Chakra flows from the core, which is near the stomach. So stopping the flow to, for example, a limb would be as easy as hitting all the Tenketsu near the shoulders, which would clog them and halt the chakra from travelling to that arm.

There is even a clan able to accurately hit the Tenketsu and disable a shinobi from using chakra..." Saburo answered instantly, remembering how the Dojutsu/Bloodline ability of the Hyuga allowed them to see the Tenketsu of people.

"But don't get any ideas... Even with your speed, it's impossible to hit the Tenketsu of other Shinobi during a fight. The clan I was talking about is just special..."

Saburo was quick to discourage Ken from trying to imitate the Hyuga.

There were many young shinobi that thought themselves special...

They ended up dying while attempting to hit the Tenketsu, thinking that memorizing them on a piece of paper would enable them to hit a moving target in the middle of a warzone...

Saburo knew that Ken was strong, so there wasn't much worry about him dying.

But he thought it would be a waste of time to even try, one needed to hit the Tenketsu with a small chakra scalpel of the same size as the hole.

It needed absolute precision, which was what made it impractical.

But Ken still found it interesting... For different reasons.

"... So, in theory... One should be able to strike the Tenketsu on their own body to halt chakra flow... Correct?"

Saburo blinked a few times while looking at his leader. The very notion of a shinobi disabling himself in combat was strange to hear... But it did make sense for Ken.

'Yeah... He only transformed after depleting his chakra... Maybe it's a prerequisite... Is he looking into ways to partially transform...'

After mulling over a few more thoughts, the researcher looked at his leader and smiled.

"Well... Only if one was to have more than one type of energy in their body..."

Ken smiled underneath his mask at that, as he realized he could use nature energy for that. Well, at least in theory, he still needed to test it.

He asked the scientists to teach him how. Saburo agreed instantly, and the two immediately got to work.

After that, Saburo and Ken spent the rest of the day pointing out the Tenketsu on Ken's body.

Saburo also demonstrated how they would be hit on Ken's body. The concept was that they needed to be clogged with foreign energy in order to be blocked.

First, Saburo clogged the pressure points for Ken's right arm... In the next few seconds, two things happened in succession.

One, his arm bulked up in muscles and transformed, growing scales while his nails grew into sharp claws...

Then, his arm turned to stone, before Ken even had the chance to clench his fist.

Saburo immediately retracted his hand, while Ken just sighed and forced the Tenketsu to open up by manipulating the chakra in his body to rush towards it.

'I was afraid of this... I'll have to look into ways to not fully stop the flow, but only restrict it heavily...'

After the Tenketsu was unclogged, Ken's arm turned to normal, and the Blind Assassin clenched his fist a few times and moved it a bit as he regained feeling in it.

Saburo was a bit surprised to see the arm of his leader turn to stone, but at that point, he knew to expect the unexpected from Ken.

It didn't even shock him to hear that Ken would turn into a statue if he fully ran out of chakra.

In the end, it was up to Ken to find out more about how to properly clog his Tenketsu. Saburo was only able to help him so much at the end of the day.

But he was able to give Ken a bit more information on another subject he had been curious of...

And that subject was Tailed Beasts!

It had taken a backseat in his mind due to Akira's situation, but now that things had settled down, he decided to find out more about them as well...

Needless to say, there wasn't much that Saburo could give Ken in terms of background.

He did help the Blind Assassin with a bit of perspective on how powerful they were...

"Tailed beasts are weapons of mass destruction wielded by the 5 great villages...

There are 9 of them in total, and they were shared with the 5 villages by the First Hokage, who had captured them all at some point...

The beasts are sealed in humans who are called Jinchūriki. They are usually stigmatized and feared even in their own villages.

They were meant to be a deterrent of sorts, but they're just used in wars nowadays. Some nations do protect their Jinchūriki more than others, but that's about it."

That was about the gist of what Saburo knew regarding Tailed Beasts. It wasn't exactly something within his field of study.

Even then, Ken was more than pleased to find out even that much.

Finding out that the Tailed Beasts were basically living nukes did give him quite a bit of perspective...

It was likely that the first Hokage had likely hoped they'd work like Nukes, and stop too many future wars from happening.

But unfortunately, the Tailed Beasts and their Jinchūriki weren't the strongest beings in their respective villages most of the time, so the wars still waged on.

As long as people could benefit from wars, they'd keep happening.

The shinobi were also nothing more than tools, with few exceptions. The true leaders of the 5 Lands were the Daimyō, who always wanted more land and riches. They weren't going to be dissuaded by the Tailed Beasts' existence...

Still, the concept of Jinchūriki greatly intrigued Ken.

'... I should look more into that in the future. Maybe I'll even see about recruiting one if the possibility arises.'

It was more of a pipe dream than anything, but it didn't matter. It wasn't like Ken was going to seek out Jinchūriki...

Although, if they were all mistreated, then it wouldn't be all that difficult to convince them to join the Dark Brotherhood.

'All in due time... For now, I still have a few things I'd like to learn from Saburo..."

"Thank you for all of your help today, Second Blade..." Ken started off by showing his gratitude, and Saburo responded in kind, by nodding and smiling at his leader.

"Of course, it is my duty as one of your Blades." The scientist's smile was still fake.

It didn't matter how much he faked care and compassion to the rest of the Brotherhood, it would never manage to fool someone like Ken. 

He was still not someone that Ken thought of as loyal. But he was still a valuable asset.

"I am still curious about one thing... I won't bother you anymore after that..."

"Oh, I wouldn't dare call it a bother..." Saburo said as he used his expert boot-licking skills. His fake smile did disappear eventually though when sensing the lack of reaction from Ken.

He had forgotten that he didn't need to keep any pretence around the blind Child. There was no fooling him...

"Why exactly are you so interested in immortality?... And why are you researching Genjutsu instead of immortality if it interests you so much?"

Saburo didn't react one bit to Ken's question, his face remaining expressionless before he blinked a few times and raised an eyebrow.

"Well... I thought you wouldn't be one to pry into my research..." The researcher sounded a bit wary, likely unwilling to give Ken all that many details about his research.

"Don't misunderstand my meaning... I by no means want to interfere with your research. I am genuinely curious..." The Blind Leader was quick to calm down the wary scientist.

He was being honest when saying that. After all, normally he wouldn't even care what Saburo was doing with his free time...

"... Very well. I can tell you a bit. It's not like it's going to harm my research in any way...

Say, have you ever heard of the Immortal Hermit?"

____________________________________________________

Hope you liked the chapter! Wasn't able to write much yesterday, went out with some friends and prolly ate something weird, cuz I felt bad for the rest of the day :)) Better now tho

Also, the 'hermit' is gonna be something more original, the Naruto world always seems to have a multitude of ways for ppl to achieve immortality, just felt like exploring some possibilities

If u want to support me look up VeganMaster on Patre_on, you'd also get 4 chapters in advance (or 2 depending on tier)