"At the beginning, you must firmly remember the movements and sensations, and pick up these elements."
"When you open your five senses, recognize the entire shape of your body, down to every blood vessel within."
"This process will be very painful, but once you remember and absorb many things, then delete the unnecessary parts, leaving only what is needed for that action, and seal it away."
"Over time, the blood vessels and muscles within your body will close up, and it will be as simple and quick as opening your eyes."
"Then light will appear, the path will open, your mind will naturally become transparent, and you will be able to see the Transparent World."
"That is a realm that can only be reached after exerting all your effort and struggling painfully."
These words were Tanjiro's father's dying instructions to him, regarding the key to opening the Transparent World.
Uchiha Nagi was in front of a bonfire, performing the Kagura Dance passed down in Tanjiro's family. As he danced, he closed his eyes, trying to feel that Transparent World. Compared to Tanjiro, Uchiha Nagi had a natural advantage; he chose to become a medical Ninja, and had a strong understanding of the human body. It was not strange for the realm of the Transparent World to be connected to the Kagura Dance.
Because the creator of Sun Breathing was born with the Transparent World, just like Hashirama's Sage Body, Sun Breathing itself was a Breathing Technique he created after observing the human body through the Transparent World.
The Transparent World came first, then Sun Breathing.
Therefore, by mastering Sun Breathing to its peak, one can reach the realm of the Transparent World. The Kagura Dance conceals Sun Breathing; by continuously comprehending and adjusting the correct breathing during the dance, one can combine it to use Sun Breathing.
If the Kagura Dance is performed incorrectly, one will only grow more and more tired; conversely, if performed correctly, it will feel effortless.
Tanjiro's father was able to dance all night in the snow with his frail body for this very reason.
"No, it's a little off." Uchiha Nagi stopped after an hour of dancing, wiping the fine sweat from his forehead.
"The Kagura Dance is correct; my copy has no flaws whatsoever. But my breathing is wrong. Everyone has a different physique, a different heart rate, so the breathing used is naturally different. I should use a breathing frequency that adapts to my own body, or one that my body adapts to, to accompany this dance."
Uchiha Nagi thought for a moment, then created ten Shadow Clones. Although Shadow Clones dissipate with even a slightly larger movement when using a Breathing Technique, they are good for accumulating experience. If they dissipate, he can just create more.
Through his research during this period, Uchiha Nagi discovered that Breathing Techniques are actually a kind of Jutsu that uses breathing to enhance sword skills and the body.
And Shadow Clones, which are themselves formed from Chakra, once amplified by a Breathing Technique, find it difficult to maintain their previous stable Chakra, which is why they dissipate as soon as a Breathing Technique is used.
However, even if a Shadow Clone can only use a Breathing Technique once before dissipating, it's still a gain; quantity leads to qualitative change, after all.
Moreover, during this time, Uchiha Nagi's body Chakra began its second development. Normally, after eighteen, Chakra is difficult to increase rapidly, but after activating his Mangekyo, it skyrocketed.
He knew that once an Uchiha activates their Mangekyo, their Chakra would increase wildly and inexplicably, but after receiving white zetsu cells in his arm, it increased even faster.
Especially after his battle with Akaza, Uchiha Nagi estimated that if his Chakra in Konoha was one Kakashi unit, then it later became two. After his all-out battle with Akaza, it has now increased to at least four Kakashi units.
So, his current body energy is roughly equivalent to four Kakashis?
If he were to fight Akaza again, he would be able to sustain himself for longer and have a greater advantage. He was improving every day, while Akaza's progress was slow.
"Caw Mission, caw Mission " Uchiha Nagi's personal crow flew a circle in the sky, then landed on his shoulder. "Hmm?! A mission?" Uchiha Nagi was a little curious; it seemed this was only the second time he had received a mission in so long.
But that's fine; he'll go check it out. He's been training for so long, it's about time to go out and test his effectiveness in actual combat.
With a few leaps, he arrived at another small mountain. The area was covered in wisteria flowers and was Kagaya Ubuyashiki's residence, though his living place was not fixed and changed periodically.
The reason was that Kagaya Ubuyashiki never allowed members of the Demon Slayer Corps to stay and protect him. According to him, if one more demon was eliminated, ordinary people would be safer, and he was useless, so it was not worth having powerful Pillars stay to protect a useless person.
Without knowing the special abilities of the Ubuyashiki family, others might be deeply moved by his words, but Uchiha Nagi knew that this family, besides their generational curse, also possessed a generational ability of partial precognition.
Kagaya Ubuyashiki once said that relying on this precognitive ability, their family had accumulated immense wealth, which allowed them to sustain the vast expenses of the Demon Slayer Corps for so many years.
Because of their partial precognitive ability, Kagaya Ubuyashiki would move his residence as soon as he sensed danger.
"Mr. Ubuyashiki, are you looking for me?" Uchiha Nagi did not address him as 'Master'; he would not be anyone's subordinate.
Kagaya Ubuyashiki didn't mind these formalities. He opened his already blind eyes and smiled, "You've arrived, Nagi-kun. Please sit, this is freshly picked wisteria flower tea."
Uchiha Nagi was not overly formal either. He poured himself a cup and waited for the mission.
"Alas, recently there's been a place where people frequently go missing. I sent swordsmen to investigate, but they all disappeared. Later, Mr. Giyu Tomioka went there but found nothing amiss; the opponent seemed to have hidden."
"Then, as soon as Mr. Giyu Tomioka left, people started disappearing there again."
At this point, Kagaya Ubuyashiki paused and said gravely, "I suspect the opponent has a very powerful Blood Demon Art related to reconnaissance, allowing them to detect Mr. Tomioka in advance. So I'd like to ask you to go, because only you possess unique Ninjutsu that other members do not."
Uchiha Nagi nodded, "Alright, I'll prepare and depart immediately."
"I trouble you, Nagi-kun."
"It's what I should do."
"By the way, after this mission, I'd like to request some time off from you; I have something I need to take care of."
"Of course."
Uchiha Nagi didn't waste much time. He immediately got up to prepare. During this period, he had taken a considerable amount of Ubuyashiki's money for various materials and equipment needed for his research. It was normal to do a favor for someone whose money you've taken.
Whether researching white zetsu cells or demon cells, he needed to purchase many things: medicinal herbs, equipment, nutrient solutions, and so on.
Recently, he added another. Genya's demon-eating constitution. Uchiha Nagi even wondered if, by analyzing Genya's ability to eat demons, he could make immortality a reality without altering his own genes.