30. Echolocation

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...

Kushina felt disoriented in the past few days. Rumors were circulating all over the village that Kumo had betrayed Honoha, and the peace treaty was just a ruse to kidnap several heirs of great clans. Hinata, the daughter of the head of the Hyuuga Clan, was abducted by a Kumo Jounin but was rescued by the crippled son of the Hokage...?

It was shocking for Kushina. That day, Himiko stayed overnight at Hinata's, and Naruto saved them from a high-ranking Jounin. It was insane. Himiko said nothing like that happened, Minato thought she must have gotten the days mixed up, and Naruto? He wasn't involved in any fight with enemy Shinobi.

Rumors had it he got a massive wound, from his left arm, across his chest, down to his abdomen. However, she stripped him down, and there was nothing! Not even scars!

Maybe it was motherly or woman's intuition, but she heard a sigh of relief from Minato behind her, and Naruto pretended to be strangely embarrassed and quickly dressed.

Furthermore, Naruto seemed to be slipping from her sight and senses. She knew her son could conceal his presence well, but she was also a Sensor with a powerful sensory ability. Earlier, when Naruto was home and hiding his presence, she could detect him, but now... he's practically invisible to her. Even when he sits next to her, at the same table in the living room as always, she can't detect him. She only sees him with her eyes, but that's it, when she looks away, he disappears from her vision.

Asking him about it, Naruto told her with a wide smile, "Don't worry, Ka-chan, I won't disappear anywhere! I just managed to break through the invisible barrier in my skills and became much better at hiding...!"

Menma had also been suspicious in her eyes lately. Everything seemed to fall into place at once, perfectly synchronized. He had started to address Naruto with more respect and talk about him with admiration. It was still the same "Nii-san" coming out of Menma's mouth, but it sounded as if he was speaking not to a brother but to his teacher or someone he should respect and admire.

Everything had been somehow different lately, maybe just fatigue? Kushina sighed, preparing dinner for her beloved family when they returned home from school or work.

...

For Naruto, the next two months after the events in Kumo had been very fruitful, maybe not as much as it had been at the beginning of his training, but it was a better period developmentally than usual.

The Sleeping Turtle Technique had been a breakthrough in his chakra frequency manipulation training. It was that final click in his head that unlocked some new possibilities for him.

He understood thoroughly how to change the frequency of chakra properly, but not only that. He could now change the frequency of almost everything in his body!

His learning speed had also been increased by training with Shizune. She taught Naruto everything she knew about "sensing and controlling the body." She now had to seek guidance from her own master, Tsunade, and delve into books to teach Naruto something new.

Honestly, Naruto didn't need Shizune anymore. She had been a good teacher before because she had experienced Naruto's training herself, so she had a lot of valuable advice that she had gained through hard work and based on her experiences. However, now she was teaching Naruto something she didn't fully understand herself.

Naruto could now conduct just as good training on his own. Shizune possessed vast medical knowledge, but Naruto also had it, additionally complemented by general scientific knowledge that Shizune didn't possess. However, Naruto's training needed to be supervised by someone, and Naruto himself preferred Shizune to control it rather than Minato sending Anbu or someone else after him. Shizune was also his older sister, whom he even liked and was grateful for all the training she had conducted with him.

Another thing Shizune taught him in the field of "sensing and controlling the body" was echolocation. It helped him quite a bit in learning to change frequencies and accelerated his training by about a month.

Echolocation was used by animals such as bats, shrews, whales, dolphins, or some species of birds. It involves using sounds to navigate the surroundings. By emitting a quiet and short sound at a high frequency, for example, clicking the tongue against the palate or clapping hands, it produces sound waves that bounce off obstacles and return to us as an acoustic echo.

Based on this, by receiving the reflected waves, one can "see" without eyes. A detailed image of the surrounding terrain appears in the mind based on the reflected waves. However, to see further, beyond one "picture" in the head, one must continuously send out more sounds and receive reflected waves from obstacles.

Naruto understood the operation of echolocation within two days. It was quite simple; his mind just had to adapt to receiving the reflected waves and imagining the surrounding terrain.

While training echolocation, Naruto walked with Shizune into the forest, where he had to move with closed eyes and sealed sensory perception. Shizune chuckled a few times as Naruto fell to the ground due to uneven terrain or walked straight into a tree, but he quickly learned, maybe even too quickly, and already half a day later, he was able to roughly "see" some obstacles. At first, Naruto unconsciously relied on his sense of smell and touch, but he quickly gave it up because he knew it was delaying his learning.

After two days, he was able to "see" a detailed image of the surrounding terrain, but they didn't stop there with the training. He still needed to refine this skill to make it more useful.

Usually, people learned echolocation in conjunction with chakra, but Naruto didn't have that option. Chakra allowed for the increase in the speed of sound, so it returned back as an acoustic echo more quickly. Chakra also allowed for a more detailed view of the image and greatly aided in learning; thanks to it, training became half as easy.

However, Naruto had to learn everything without using chakra. Sending out sound, it would return within a fraction of a second, sometimes within a second if the obstacles were far enough, and an image would appear in his mind after another second passed. Naruto desired to shorten this time to the absolute minimum so that echolocation could be used even in combat. This was the first fundamental thing Naruto wanted to improve. The next was changing the frequency of the sound he emitted. Some animals or trained individuals could pick up this sound and anticipate his movements or deceive him during combat. He couldn't allow that, so he tested which frequencies animals and people could hear and transmit. Naruto established several frequencies he wanted to release using echolocation so that no one could hear them. In case, he also tried to learn to receive waves and create an image in his mind, several frequencies at once, or creating a continuous "movie" using several frequencies alternately. It was very exhausting, and receiving several waves at once and "seeing" from them was quite painful. However, the headaches didn't stop him, and he tried to adapt his mind to such work for many hours.

Naruto also concluded that if some animals can communicate through emitted sounds and frequency, he himself can do it too. However, no one he knew among people could practice this with him, so Naruto decided to try communicating with animals.

The speech of less intelligent animals, which are guided only by their instinct, was quite simple. Naruto was able to communicate among them and gather some information like "danger," "hungry," "my territory," "I will kill you," etc. It was a simple and concise communication that he even enjoyed. Less intelligent animals couldn't lie and mostly said only what they thought. Some animals didn't want to talk to him and avoided or fled from him, but it was rare. For each species that he could communicate with through sound and frequency, he had to choose the appropriate frequency to talk to them because sometimes they couldn't pick up some frequencies that he sent to them.

Echolocation could be added to the Sensor skill, and now Naruto has another way to detect other forms of life. He doubted anyone could find a way to hide from echolocation, and even if they somehow destroyed the waves sent to them, it would be quite suspicious, and Naruto could figure it out.

For two months, Naruto mixed frequency change training with echolocation, as well as better understanding and manipulation of heat energy in his body.

He was able to understand heat enough to heal minor injuries and cuts with it. However, the best thing according to him was the ability to ignite his cells and produce fire! It was an uncontrolled flame, but he hoped to control it in the future.

In secret from others, he ignited his cells and endured tremendous pain to learn to control it, but for now, it was too difficult. First, he had to understand and control heat deeper to later move on to fire control.

Another thing, and precisely the opposite of fire, was cold. Naruto could freeze some cells of his body, but then he lost feeling, and he doubted he could control it. If there was such a possibility, it was certainly several times more difficult than fire control.

...

Naruto was currently spending time in his private laboratory, which he took over from Orochimaru. He read all the documents they had acquired over the past few weeks. Due to continuous training, he had no time to look into new information his laboratory discovered about the Chakra Circulatory System and Chakra Cells. And as he expected, nothing significant had progressed.

Naruto clicked his tongue in annoyance and pushed the papers away even further. He had nearsightedness, and it was getting worse. He had to add Chakra to his eyeballs lately to improve his close-range vision. Naruto had strong eye muscles and could see excellently at a distance, but not up close. Nearsightedness is incurable, and there's nothing he can do about it. Maybe if technology and medicine advanced... but that's not happening for another ten years, and by then, he might not be in this world anymore.

"I should probably start wearing glasses, but then my eyes will weaken, and they won't try to maintain their sharpness on their own..." he sighed heavily. Maybe he should start exercising his eyes with Ayurvedic glasses? However, it only strengthens his eyes for long distances; it won't do anything for nearsightedness.

But he probably should start doing that anyway. Sharp long-distance vision would come in handy.

Naruto set aside the documents, there were plenty, but he managed to read them in just a few minutes. His reading speed was enormous. From the previous 4,000 words per minute he was able to read, it changed with experience in speed reading to 9,000, per eye. He could read with both eyes, two pages, one eye per page. It was very useful, especially when he had a bunch of documents to read in the Research and Science Department.

At some point, Naruto also began to wonder if he could comprehend the entire text without reading? Because look at it this way, do you see any landscape, a city, a city gate, people, or anything? Do you have to mentally tell yourself that you see every detail? No, so why should Naruto read? He would just look at the paper, and the text should enter his mind fully understood.

But to do that, he should also learn peripheral vision, so learning to understand text without reading will be suspended for now. Peripheral vision probably belongs somewhat to the field of "feeling and controlling the body." It's an ability that Shinobi can acquire unconsciously during combat or consciously learn due to its immense usefulness. Naruto has already mastered it to some extent, but it's still nothing, and he has a long way to go for further development.

By the way, maybe he can increase his field of vision. An ordinary human sees about 180 degrees around themselves, but maybe there's a way to increase that? Even minimally?