CHAPTER 41

"I already have the basic prerequisites for developing the enhanced Body Replacement Technique. Next, I need to put it to the test."

With at least three more months of training ahead, Uchiha Kiyo had ample time to conduct his research. He had studied the fundamentals of sealing techniques for years, and his dedication had not been in vain. Among the Uchiha clan, he had arguably the most comprehensive understanding of sealing basics, and his serious approach to learning gave him a solid foundation. This was why he had been able to master all basic applications of sealing techniques in just three months.

However, basic sealing techniques were exactly that—basic. Similar to a rudimentary binding seal, even a physically strong individual could break free from them. Yet, Uchiha Kiyo wasn't focused on the immediate effect but rather on how techniques could be layered and combined, much like the small chakra cycles he had previously incorporated into his Earth Release techniques. By understanding these fundamental interactions, he believed that more complex and effective sealing jutsu could be developed.

The process, however, was far from simple. The number of potential combinations was staggering. Simply stacking two techniques together, like "123" and "425," wouldn't necessarily produce a functional result. The correct order might need to be something like "142325." Some sequences allowed for shared symbols, while others required distinct, non-overlapping components. Furthermore, sealing formulas didn't just follow a linear arrangement—they extended across planes and even three-dimensional space, making the process significantly more complex.

The above was merely a simplified analogy for understanding. In reality, no functional sealing jutsu was composed of fewer than ten interwoven components. The sheer number of possible permutations was overwhelming. However, thanks to his solid foundation, Uchiha Kiyo could swiftly eliminate incorrect sequences, and his knowledge of mathematical permutations and combinations from his previous life gave him a distinct advantage over other shinobi.

"First, let's set a small goal—develop a sealing formula capable of temporarily storing chakra in a kunai."

Having set his objective, Uchiha Kiyo resumed his rigorous training regimen.

Each morning, he started with intense physical conditioning. His progress in this area had been notable, and he had reached the point where weighted training was beneficial. He had invested in two sets of weights—10 kg and 20 kg—switching between them based on the intensity of the session. During workouts, he used the 20 kg weights, while he wore the 10 kg weights throughout the day.

With the Self-Cultivation Technique reinforcing his body, Uchiha Kiyo had little concern about overstraining himself, allowing him to push his limits confidently. He wasn't some mindless brute, after all. The weighted training yielded excellent results, and his physical growth had accelerated significantly.

Feeling the rapid improvement in his physical abilities, Uchiha Kiyo was particularly diligent in his training.

"Still, the physical enhancement from exercise lacks that 'evolutionary' sensation that comes with the Self-Cultivation Technique."

Unlike the transformation induced by the Self-Cultivation Technique, which seemed to push his body toward a higher state of being, standard physical training simply strengthened his existing form. But for now, that was sufficient. Since he had yet to fully understand the deeper potential of this "evolutionary" sensation, there was no rush to prioritize it.

His daily schedule was methodically structured. Mornings were dedicated to taijutsu practice. After lunch, he focused on refining his Self-Cultivation Technique. Afternoons were spent on ninjutsu, alternating between learning new jutsu and improving proficiency with existing ones. Once his chakra reserves were depleted, he shifted to studying sealing theories. After dinner, once his chakra had recovered, he would continue developing his sealing techniques.

Orochimaru observed Kiyo's diligent training and, satisfied with his progress, refrained from excessive interference. Instead, the Sannin focused his attention on Nawaki Senju and Sarutobi Shuo.

Sarutobi Shuo was relatively easy to train—he possessed solid talent and a strong foundational knowledge, allowing him to grasp new concepts quickly.

Nawaki Senju, on the other hand, was a different story. Though Uchiha Kiyo had spent years answering his endless "why" questions at the Academy and imparting bits of knowledge, it had only been enough to help him pass his graduation exams. When it came to theoretical knowledge, Nawaki was severely lacking.

And Orochimaru wasn't the type to overlook such a flaw.

Under Orochimaru's strict guidance, Nawaki was forced to study theory extensively every day, undergoing constant assessments to ensure his progress. For someone with little patience for book learning, this was nothing short of a nightmare.

But Orochimaru didn't stop there. Given Nawaki's naturally large chakra reserves, he was subjected to rigorous chakra control exercises. There was no point in possessing vast chakra reserves if they couldn't be effectively utilized. Ideally, he would learn a variety of ninjutsu to capitalize on his chakra pool, but his slow learning pace made that impractical. Instead, he had to refine his chakra control first.

Good chakra control wasn't just beneficial for medical ninjutsu—it played a crucial role in mastering various other techniques. Many jutsu required precise chakra manipulation to be performed efficiently.

As for Nawaki's suffering… there was nothing Uchiha Kiyo could do to help.

This was karma at work. The saying goes, "If you don't study when you're young, you'll regret it when you're older." Though Nawaki wasn't old, the principle still applied—his earlier laziness had led to his current predicament.

…

"If I position this formula here, the technique should flow more smoothly. By integrating barrier techniques, binding seals, and reinforcement seals, I should be able to effectively store chakra, right?"

Uchiha Kiyo carefully inscribed the newly formulated seal onto a standard kunai. Confirming that there were no conflicts within the pattern, he finally exhaled in relief.

Over the past three months, he had meticulously combined basic barrier seals, restraint seals, and enhancement seals into a functional formula. After countless adjustments and refinements, he had finally stabilized the structure. If everything worked as intended, this would serve as the foundation for improving the Body Replacement Technique.

Throughout this process, Uchiha Kiyo had burned through five or six kunai per day. Though they were standard issue, the financial burden was noticeable. To offset these costs, he had been taking on one or two D-rank missions daily for the past three months.

Now that the technique had stabilized and kunai were no longer being destroyed, he could finally breathe easy. Any further losses would have been unsustainable. Even within Konoha, there were only so many D-rank missions available, and the village restricted higher-ranked shinobi from overfarming low-level missions to prevent a drop in task quality.

Uchiha Kiyo placed his right hand over the kunai and slowly channeled chakra into the seal.

"Phew… it's stable. Looks like these three months weren't wasted. The sealing technique successfully stores chakra. Time to test its limits."

He continued injecting chakra into the kunai, pushing the seal to its capacity.

Boom!

The kunai shattered—the seal had reached its threshold and failed.

"So, the limit is about ten units of chakra? No… to ensure stable operation, it's best to keep it at eight."

Uchiha Kiyo analyzed the results.

To be honest, he wasn't entirely satisfied. The Body Replacement Technique consumed roughly half its chakra cost in preparing the substitute, meaning the stored chakra dictated the technique's effective range.

With a maximum of eight units of chakra stored, the substitution distance was inevitably constrained.

At his current level, the technique functioned as follows:

3 meters → 1 unit of chakra

4 meters → 5 units

5 meters → ~15 units

6 meters → ~30 units

10 meters → ~120 units

The further the exchange, the exponentially greater the chakra cost. This diminishing efficiency was the primary reason why space-time ninjutsu was often impractical.

"Oh well, maybe I'm being too demanding. A five-meter range is already useful in combat. It's a decent start, and there's still time for improvement. Maybe adding a few reinforcement seals will help… Yeah, that's worth testing."