Six Months

Natsume trained between the Monkey Geri technique and practicing fuinjutsu constantly without breaking her routine once. A few weeks into her training, Saru had begun watching her after bringing her food from the back mountain. After a month, she was able to complete a hundred laps with chakra alone. Another month after that, she was able to complete a hundred laps with just her physical body.

During this period of time, Natsume ate a lot of food from Mount Kakazan and an awkward situation arose. Her physical growth had sped up because of the nourishment and constant training. She quickly outgrew her formal clothes in three months, and her training clothes in four. When Saru came to bring her a tiger skin kimono matching Enma's, although tacky, accepted it with grace. After that day, Saru wouldn't just watch, he joined in and became Natsume's training partner.

After succeeding in doing a hundred laps with her body, she switched her daily activities to a hundred laps of Monkey Acrobatics, then repeated her formula with Monkey Strength. She discovered that the stones placed around the arena were graded. She tried to lift them with her peak strength without utilizing Monkey Strength but could only lift the first rock slightly. The others were impossible. Saru came over and attempted the same and did a bit better than her.

Monkey Strength focused on explosive power from rest. The image of the old man replayed in her mind. He would turn soft and calm. Then, in an instant, power exploded from every muscle in his body and released a strength higher than normally possible. Unfortunately, even after a month of training, Natsume saw minimal results. She could lift all but the last rock with chakra. On the fifth month, she decided to try her physical body alone and discovered the technique was significantly stronger.

She held the second to last rock up for a whole second and threw it down while heaving a sigh of relief. Natsume figured out where she was wrong at that moment. It was not just about exploding in physical strength, but also in all aspects. Therefore, she stood in front of the last rock and withdrew her presence. Her body went slack, and her chakra was carefully withdrawn.

Then, in an instant, all of her strength exploded simultaneously. Chakra burst out of her tenketsu, her sharingan went straight to three tomoe and her muscles contracted. The stone which she could not lift flew straight into the air for fifteen feet before coming back down with a large bang. Saru became inspired and started mimicking her. Although he couldn't reach the same level of explosiveness as her, he was able to break through his limits and pick up the second to last rock.

At the start of the sixth month, Natsume had finally finished lifting the last rock a hundred times in succession. At this point, she had to change her kimono again. Since she did not have a way to measure herself on the mountain, she could only use Saru as reference. In his normal form when she first arrived, she came up to his chest. Now, she came up to his chin. This distance was about the length of her forearm. Using some simple measurements, she estimated it was around 65 inches tall from around 60 inches. While resting in her cave abode, she turned her attention to the fuinjutsu practice.

…

Over the last 6 months, she had made countless failed products. However, with each failure, she learned something. The fundamentals of fuinjutsu were the formula and the energy source. Since she was capable of sensing Nature energy, it was initially easy for her to switch the source to Nature energy. However, fuinjutsu was ultimately a technique invented with chakra in mind. Also, Orochimaru did not seem to be able to sense Nature energy, so her initial approach was wrong.

After discovering this error, she changed her focus to the formula instead. By keeping chakra as the source, she altered the formula to pull in and seal Nature energy. In the end, the Four Symbols seal and the Eight Trigrams seal came into play once more. Therefore, she decided to focus on recreating the Four Symbols seal since it became her bottleneck in recreating the curse seal. After three months of practice, she finally made a breakthrough.

Through repetition, she was able to stumble upon the right direction. It took her two more months to create a partially functioning seal. However, it couldn't be called the Four Symbols seal anymore. She was not a genius like the future Fourth Hokage, so she could only make a weaker seal for her own uses. However, this failure was an opportunity because the main issue with her seal was that it leaked. Unfortunately, she had run out of chakra paper at that point, so she took a break to focus on completing Monkey Strength.

…

While resting and recollecting, Natsume heard Saru enter her cave abode with more food. She walked over and ate half of the fruits he brought. Her appetite had increased a lot since her daily chakra expenditure was massive. Before, she could barely be considered top-rank due to her Mangekyou Sharingan. However, even without the Sharingan, her chakra had grown past the standard for a top-rank warrior.

The problem was, she did not know how their current ranking system compared to the future shinobi world. Therefore, she did not become complacent with her strength. God-tier shinobi would exist in the future that could destroy a country. Although her chakra levels were high, that was not the only thing needed to be a powerhouse once the ceiling of strength rose. The young jinchuriki in the future had chakra comparable to the leaders of villages yet was unable to beat them in a fight.

"I've been here for six months, Saru." "Ooh-ooh-aaah!" He gave her a thumbs up which always made her smile for some reason. "Hey, do you want to try breaking through to the peak with me?" To this question, he jumped up and down nodding his head. "Alright, lets work hard!"