Chapter 5: Chakra and Rock Lee

After dinner, Natsuro returned to his room and took out the book related to chakra extraction, beginning to read. To be honest, he had never studied so diligently in his previous life.

He already had a basic understanding of chakra. However, he didn't know the exact method of extracting it. He had previously asked his mother to teach him, but unfortunately, she said that while she could still use chakra, she had returned most of her knowledge to her former instructors. She also advised against extracting chakra before the age of six, as it could have some impact on the body.

He had thought about chakra a lot. Chakra is a combination of physical energy and spiritual energy. Extracting chakra inevitably affects the body.

Spiritual energy determines the amount of chakra that can be extracted at once, while physical energy determines the total amount of chakra one can have. Only when physical energy is extracted and combined with spiritual energy can it be used as chakra.

In Natsuro's view, physical energy is influenced by physical fitness and bloodline. Physical fitness can be improved through training, but the bloodline is mostly fixed.

Ordinary people have a low bloodline coefficient, so they need a high level of physical fitness to have a sufficient amount of chakra. However, certain bloodlines, like the Uzumaki clan, have a very high coefficient, so they don't need to be exceptionally physically fit to possess a large amount of chakra.

Moreover, bloodline affects not only the amount of chakra but also the speed of recovery. However, this is not a major concern, as battles are often decided in just a few moves, so recovery speed doesn't have a significant impact on a single fight.

He had previously wondered if there were any treasures in this world that could enhance one's bloodline coefficient. After thinking it over, he realized that there wasn't much he could do. Hashirama cells? He wasn't keen on becoming a half-human, half-monster. He'd rather try to control a tailed beast, but even that didn't align with his goals.

Afterall he wanted to grow to the peak of his abilities as a human. Even if other forms were stronger, he preferred to remain human. So whether it was turning into a monstrous form or becoming a jinchuriki, it didn't fit with his goals.

As he read for a while, Natsuro felt that his food had digested, so he closed the book.

"Mom, I'm going out."

"Come back early, and stay safe."

Shinai was already used to him going out every day. She thought he would take a break from his usual routine after starting school today, but he still insisted on going out.

But he wasn't going out to play. Since chakra is based on one's physical condition, he decided not to slack off. To avoid the risk of running out of chakra after using just a few jutsu in the future, He had begun to commit to his training regimen.

He'd estimated that despite his consistent training, his current physical condition was only equivalent to that of an ordinary second-year student.

However, recently he noticed that although his training intensity hadn't changed, his body felt better, likely due to his age. So, he thought it might be time to increase his training volume.

Considering this, he knew he had to experiment to find the right balance. He wanted to push his limits without overexerting himself. After all, his body was still that of a six-year-old, and he needed to ensure he had enough energy for growth. It was important not to sacrifice long-term gains for short-term improvements.

However, he could push himself a bit more occasionally, just to test his limits.

This wasn't too difficult for Natsuro, likely due to his strong soul. But the last time he pushed himself too far, his body felt drained for days afterward. Since then, he had avoided reaching that level of exhaustion.

But now, he felt like it might be worth trying again. So he silently made his way to a secluded training ground, where, as expected, someone was already there.

It was none other than Rock Lee. He had become very familiar with him by now. Every time he came to train, Lee was already hard at work. And when he finished, Lee was still going strong.

Yes, this was Rock Lee—the hardworking genius, marvelling at Lee's endurance. While he believed his own theoretical potential might be higher, that was assuming unlimited growth time. In reality, the human growth period is limited, and he wasn't sure if he could reach his theoretical limit before that time ran out.

So, while theory is one thing, reality is another. And for now, Natsuro didn't see himself surpassing Lee in physical endurance, nor did he have any desire to. After all, he had witnessed Lee's relentless effort firsthand.

"Oh, Natsuro, you're half an hour late today. You need to do extra training!" Lee's eyes lit up when he saw him. Although he was used to training alone, having a partner made him even happier.

"Sure." Natsuro agreed, having already decided to push his limits today. A few extra sets might not be enough.

Lee was surprised by his response. In the past, he had never agreed to extra training. Lee's eyes seemed to ignite with passion.

"Oh, you actually agreed! This is what youth is all about! I've decided—I'm going to reward myself with a few extra sets today too!"

Natsuro couldn't help but feel a bit embarrassed. Even though he had seen this reaction from Lee many times before, he still found it a bit over the top.

And so, today's training began. He took his position on the other side of the training ground. Although they trained in the same area, he and Lee had different methods.

He believed that since his body was still growing, he shouldn't engage in overly intense training. He preferred to do lower-intensity exercises over a longer period to accumulate gains gradually.

Time passed, and even though the intensity wasn't high, Natsuro was soon out of breath. However, he hadn't yet reached his goal for the day. His body was nearing its current limit, but mentally he felt he could push a bit further.

Lee, watching from the side, was moved to tears. This was truly the spirit of youth!

In Lee's eyes, Natsuro's movements suddenly became more fluid. Lee recognized this feeling well—he experienced it often. This was what youth was all about!

This time, Lee really did shed tears of emotion.

"Finally made it," Natsuro muttered to himself, realizing that his limits were even higher than he had expected. In fact, this wasn't his true limit, just the upper threshold his body could handle at the moment.

After training for a while longer, he said goodbye to Lee and left, his steps heavy with exhaustion. Although his body was tired, his mind was still sharp. He decided to read some more when he got home, aiming to learn how to extract chakra as soon as possible.

The next day, he was surprised to find that he felt fine. Was his body improving that much? So, he decided to push his limits again.

However, by the third day, he'd hit a wall. His body was constantly fatigued, so he could only manage basic exercises. It seemed that while he could push himself, he couldn't do it continuously. This was the interval Natsuro needed to figure out.

With a sigh, he acknowledged that the path to physical training and chakra accumulation would be a long one.