(28 April, year 54 AK)
As Yuta returned to the desolate training grounds in the morning, he felt a little bit off still, and his mind was still a bit tired due to the three days of non-stop training.
'Screw those pills, I rather make more repetitions of these three days than use those pills again to train non-stop. I had avoided the physical body backlash of the pill by time-traveling, but it still exhausted my mind, and it will take a day or two to fully recover from it, better to train with breaks and a full night sleep than do it non-stop like that, no need to overwork myself to the death.' Yuta thought as he resumed his training.
The hours flew by as Yuta was trying to figure out how to infuse his chakra into the sound. He spent most of his time training, and making small breaks every now and then to go grab something to eat at some food stalls or restaurants, only returning home to sleep, and whenever the third day were coming to an end, Yuta would time-travel back to the 28th of April to repeat the cycle.
In the past, all the futile efforts of infusing chakra into sound were always irritating for Yuta, but now he had fallen into the routine flow and just pushed forward, the irritation he felt before was faded away and only thing that left was the monotonous routine and constant every day's effort while days was continuously passing by.
At first Yuta wanted to count the days he spend inside the time-loop just to keep track, but after he counted thirty days and returned back for eleventh time, he just given up on counting days, instead he paid attention to the steady rate of his spiritual energy and chakra growth, with the current rate, Yuta calculated, it would take about two to three years to catch up to Itachi's and Hikari's chakra reserves.
Yuta thought about Itachi's chakra level, at this point in time with his chakra senses he felt it was slightly stronger than Mamoru's chakra, who Yuta used as the measure for an average Chunin's level of chakra. After comparing this levels to the Genin level of chakra that he concluded before, Yuta tried to summarize it into a numerical value, it was hard to do only based on his senses of chakra alone, but in the end Yuta concluded that a Chunin level of chakra is about ten times of the amount of a Genin.
Based on that theory, Yuta calculated, that his own chakra is about 2G right now, that means it's about two times of the average Genin, based on that, Chunin level is equals 10G or 1C on that scale, Mamoru's chakra equals 1C, and Itachi's and Hikari's chakra both equals about 1.2C or 12G.
'Damn, this is depressing...' Yuta thought as he calculated the supposed numerical values of chakra in the middle of his training, 'During the graduation Itachi's chakra felt slightly weaker, about 1C or 10G, but only after a month it grew to 1.2C, same with Hikari, while my own chakra was about 1.8G back then, and it is about 2G now, after a month of training with Shisui and a month of training in the time-loop.'
'But my chakra level grows not at a constant rate, it actually slightly accelerates over time, if not for that then two or three years won't be nearly enough to catch up to Itachi and Hikari. In simple terms, to grow chakra level from 0.5G to 1G takes almost the same amount of time as from 1G to 2G, in both cases chakra grows two times over, but for the latter it gets two times more in its amount than for the former.'
'Although it's the case right now, I already can feel that this acceleration of chakra growth is slowing down and at some point, it will stop completely. For example, I already could tell that growing my chakra from 2G to 4G will take a while longer than it took me to get from 1G to 2G.'
'To sum it up, while Itachi gained about 2G of the amount of chakra, I gained less than 0.2G in the same amount of time. At moments like this, I almost regret not choosing talent all the way back in the black void...' Yuta thought while continuing his training.
And although Yuta was thinking almost regretfully about not choosing talent over the Time Control, in truth he didn't regret it one bit, he was actually very content with his previous choice, and he was just being a little bitter that he has to work much harder to achieve the same results as more talented individuals like Itachi.
The days flew by with Yuta being unbothered to even count them. At the end of each three-days cycle Yuta's palms were aching severely due to the overuse of chakra during his training, as he was constantly trying to push his chakra through his hands into the air to attach it to the sound wave his clap produces.
But Yuta didn't mind the pain and ignored it completely, as if it wasn't his hands that were hurt at all, and Yuta treated it more like he would treat a health indicator in the video game, ignoring it as something insignificant.
With his time-travels and his body's conditions being reverted all the time to its previous state, at some point, unbeknown to him, Yuta's pain tolerance grew to an unreasonable degree, it happened mostly because he stopped treating his body during the time-loops as something important or something worth caring about. And since that was the case, the pain signals his body was firing into his brain became something insignificant to him and he started to ignore the pain without much effort.
And although Yuta's spiritual energy and chakra is constantly growing, allowing him to output more and more chakra during his training, at the same time his physical energy and the chakra network that are intertwined with his physical body and could be considered partially physical as well – didn't grow at all due to the time-travel reversals of his whole body.
The physical aspect of his chakra network that comes from the physical energy wasn't being trained to withstand the constantly growing amounts of chakra that are being pushed through his hands all the time, and because of that, injuries that his hands were accumulating by the end of each three-days cycle was constantly worsening.
And although the chakra network comes from both, spiritual and physical energies, and it's improving alongside the growing spiritual energy, the physical aspect of it that comes from physical energy didn't improve inside the time-loop, hence the hand injuries, since Yuta's hands wasn't trained to withstand the growing amounts of chakra being pushed through them.
But despite that, Yuta continued to push forward.
The days continued flying by in an established routine.
Then at some point, after another clap of his hands, on the verge of his chakra sensibility, Yuta vaguely felt something unusual, it lasted only for an instant and it felt like a weak flash of chakra that Yuta sensed all around him, but it only lasted for a fraction of a second and disappeared as fast as it appeared, leaving Yuta unsure if he really felt it or not.
'What was that?' Yuta's mind was racing with thoughts, trying to process what happened, he was going through his attempts for a very long time now, and feeling something new during his training had startled him.
Yuta made another clap, but this time he didn't feel anything unusual.
'Just a fluke then?' He thought while feeling dejected, for a moment he thought that he had finally succeeded in his attempts.
Yuta quickly suppressed his negative feelings and instead he briefly went into his mindscape and returned, channeling the calm state of the River of Time back into his body.
Now, being completely calm while the River of Time washed away all his turbulent emotions, Yuta analyzed what happened before, he recalled perfectly the exact way he channeled his chakra through his hands on that particular attempt and the feeling he had with his chakra senses.
While keeping that exact memory fresh in his mind, Yuta tried to replicate it, he clapped his hands once, twice, multiple times, trying his best to replicate it...
After twenty claps or so, Yuta finally felt it again, the weak chakra flash in the air that lasted for a fraction of a second. This time, being fully concentrated and ready, Yuta sensed it more clearly, it wasn't just a chakra flash, it was like a fast moving wave that burst from his hands and instantly flew in all directions.
'No doubt about it, this is it.' Yuta's calm mind was quickly and carefully committing to his memory all the details of how he moved his chakra and what he felt in the process.
After that, Yuta clapped his hands a few more times, and on his third time he felt it again. A few dozen more claps and now he was reproducing the same chakra wave each time without fail.
Yuta continued to clap a bit more, to completely memorize the feeling and to further his understanding of how exactly he was doing it.
After a few minutes, Yuta let go of his calm state and his emotions returned back to him, he was instantly being overwhelmed with excitement.
"I did it, I can't believe I actually did it!" Yuta said loudly in an excited tone.
Only now he finally felt as a huge psychological burden was removed from him, he felt very relieved right now, only now Yuta realized how much this bottleneck had burdened him and how much it was weighting on him that he wasn't able to figure out how to use sound for his genjutsu even after so much time and effort.
Subconsciously, Yuta was starting to feel desperate, and although he was always telling himself that he could do it, after so much time and effort he subconsciously started to doubt himself, only now that he finally did the thing, he felt an extreme sense of relief and accomplishment, he wasn't aware of how much he needed that up until this moment.
'Now that I figured out the hard part, the next steps of actually using the sound in a proper genjutsu will be much easier...' Yuta thought excitedly.
--- AN ---
Initially I thought this time-loop would only take one or two chapters at most, but then I sidetracked by one thing after another, and here we are, two chapters in, and it's not even halfway done. I'll try to sum it all up and end the time-loop without being sidetracked by something else again in the next chapter, but no promises though.
Also, I initially thought that the chakra network is something physical, like blood vessels, and it actually physically exists inside the body, and you could see it if you cut the body open. But after some more research, it seems that it's not the case. Although the network is intertwined with the body and it's limbs and organs, the network itself isn't physical in a sense that it doesn't have any mass and it doesn't actually take physical space inside the body, it's a more spiritual thing than physical, but it's connected to physical things like organs and such.
Thanks to Krishna_Razz, Eyes_Of_The_Void, Loalola, waltersaaron16, Daoistbm0BeO, AdamD4C, 676867 and GokageSensumo for the power stones. We've got more than ever stones during this week - 74, and got into top-192 of the seasonal power ranking, thanks guys!