When Hisame's chakra tried to fuse with the bone marrow in the innermost layers of his skeleton, the chakra within the body of Haru exploded.
It was as if his chakra was conscious, and it conveyed feelings of anger, anxiety and frustration that deeply unsettled Haru's mood.
Of course the chakra of the white haired boy was not sentient. Rather, it was a way for his body to tell him that it felt bullied and endangered by the intrusive endeavour of his mother.
And the feeling was not pleasant. Seconds passed, and as his discomfort increased so did his chakra rage out.
"Tame your bones, son."
Haru was stunned for a heartbeat. His body ache and discomfort made him lose himself for a while. Indeed, he knew what to do.
Circulating his chakra through his internal meridian network, Haru gently repelled Hisame's chakra who cooperated tacitly. As he recalled the way the peculiar energy stored within his bone marrow bust out previously, he decided to inject his meridian's chakra inside his bones.
Every single bit of discomfort that he felt previously disappeared instantly. Instead, Haru felt an unprecedented feeling of warmth that rapidly intensified throughout his body.
It was as if he had taken large sip of burning hot chocolate in a state of hypothermia.
This mysterious energy that slept within his bone marrow that repelled his mother's chakra so vehemently was now embracing his, connecting his meridians to bones one by one, forming an extended network which now encompassed his whole skeleton as well.
This evolution triggered an all out reaction that brought tremendous changes to his body.
His physique, which was already exceptional in its own right and brimming with vitality, was now undergoing an unprecedented increase in cells activity, nourished by the overflowing chakra of his bone marrow. His muscles became more compact, stronger, and he had the odd feeling that they were now in some way different.
"The feelings you experience now are normal, Haru." explained his mom, who anticipated his puzzlement. "The awakening of the Shikotsumyaku does take the yang physique of our bloodline to the next level."
"Not only will your chakra usher in an explosive growth for the next few days due to the rise of the yang attribute of your body, but your regenerative factor will also rise threefold in order to handle the constant tearing of your flesh. Actually, the body is smarter than you think. Did you notice ?"
Haru had a vague idea but he wasn't sure so he asked. "I'm not sure, something feels fundamentally different about my flesh. What is it ?"
"You see, although our healing factor is high, it would be quite cumbersome for a Shikotsumyaku user to regenerate torn muscles, veins and meridians in the middle of a fight." She explained, and Haru agreed as it was something he has long been puzzled about.
"The awakening of the Shikotsumyaku also comes with the natural capability to displace our flesh and internal organs to some degree to avoid tearing it up. For example if you want to create a bone weapon with the your arm's humerus, only your skin will actually be torn up. Convenient isn't it ?"
It wasn't until now that Haru realised how insanely good this Kekkei Genkai actually was.
Had the extracted bones truly torn the user's flesh, then even though their healing factor would have negated any injuries within a few minutes it would have brought major problems of internal chakra flow disruptions or weakening muscle efforts amidst of a high intensity battle.
I would have been indeed quite inconvenient, to say the least.
"This ability is sometimes called the Nikutai no Henka. I would not have been injust to call it a Kekkei Genkai of its own if it wasn't tied to the Shikotsumyaku." Taught Hisame patiently. "Its instinctive use for the Shikotsumyaku is only the tip of the iceberg. The warriors who mastered this ability to an advanced degree can even shift their organs at will, avoiding damages from strikes that should have been lethal. When its paired with the healing factor of the highest level this body is considered the semi-immortal physique. Those who have achieved it in the clan can be counted on one hand."
It wasn't hard for Haru to understand why the clan paid so much attention to this Kekkei Genkai in particular now. It could be said that when properly developped its power was at least comparable to a Mangekyō Sharingan.
If the high level evolutions of of the Byakugan were not considered, it could be considered the best out of their two regular blood limits by far. It was the true foundation of their clan's power.
Of course if somehow someone like Byakuya managed to develop his pupils further, the story would be different.
But what was the likeliness of such a thing happening ?
Haru stood up under his mom's gaze, and without saying a word a bone spike emerged from his fingertip. A rare joyful smile took shape on his face with the realisation that he truly awakened the valuable Kekkei Genkai, one that would surely revamp his fighting style from the ground and take his power to heights no other kids of his age and even older had reached.
Hisame, who was still sitting on the ground in front of him, had a small grin as well. She was proud, knowing that when the other main family elders would come to know of his talent in the upcoming public battles of the academy, Haru would earn their household a lot of face. It was far from the days of relative infamy they still endured not so long ago.
"Alright your body is still in a transitory period so we'll wait for a few days before beginning proper training." Explained his mom. "In the meantime you will practice genshu and meditation. As your yang attribute strengthen it's also equally important that you stimulate your ton attribute as well to maximise the growth of your chakra."
This made perfect sense, as chakra was a mixture of yin and yang releases at the fundamental level.
Haru nodded, and replied. "Hm do you have any genshu technique to teach me, mom ? They haven't taught us anything yet but basic theoretical knowledge at the academy."
"Oh…" The white haired woman was a bit surprised, and then frown for a while. "That's going to be a problem. The practice of genshu has prerequisites. You will need to master some yin release chakra control exercices, and it might be too late to begin genshu practice by then."
Haru frowned too. If there was something that he was truly mindful of, it was the growth of his chakra reserves. It was of paramount importance to anyone who sought to reach the heights of his ancestors and the level of the Ōtsutsuki race.
Following the current trend of the growth of his chakra, he expected his chakra reserves to grow to about thirty to thirty-five gans by the end of the week.
This would make his reserves comparable to someone like Akihiko, a decent sophomore student of the main family.
Such an outstanding growth was far superior to the average effect of Hamura's meditation technique, which increased his chakra by twenty to thirty percents in the early stages.
Compared to the fifty to seventy percents increase brought by the awakening of the Dead Bone Pulse, it was truly inferior.
Although it was a one time improvement that did not seem so significant at first, increasing his reserves by not ten gans and a half, it was of utmost relevance in the eyes of Haru.
The growth of chakra followed the rules of compounding. For Haru who has been taught in the ways of modern mathematics in his previous life, the ten gan difference of today meant that in a few years that gap could widen to hundreds or even thousands of gans.
Every additional gan that he could get now was not something that he could afford to pass by.
For a while, both Haru and Hisame were silent, pondering about possible solutions. Observing her mother's incredible amount of chakra with his Byakugan, the towering volume of her nearly two thousand gans blinded his sight with its brightness.
It was even a fair bit bigger than his father's, who barely crossed the one thousand gans mark. It was an amount that Haru estimated to be a bit bigger than Naruto's during the Shippuden period.
As his retina became slowly overwhelmed with his mother's chakra radiance, his eyes began to secrete moisture in an attempt to shield them from the harmful phenomenon.
Noticing that her son's eyes were beginning to tear up, Hisame admonished. "Don't look at at people too much with your immature Byakugan. Your optical nerves are still weak and can't withstand the sight of grade-3 warriors chakra and above. You should know this."
"I couldn't help it, sorry." Haru apologised, a bit depressed. "I think… I might have an idea. Isn't sensing a yin release technique ? I might as well just practice that."
"You're right, that's a bright idea Haru." Hisame smiled happily. "I didn't know that you had picked up the sensing skill. Most students of the main family neglect it."
"I've just read the skill scroll's introduction for now." He clarified. He still had yet to actually practice it. "By the way, I've been invited by the matriarch to attend to her daughter's birthday party. Do you have any ideas for a suitable gift ?"
…
"When is it ?"
"Well… We should have about an hour or two left, maybe ?" Haru answered, a bit unsure himself.
Hisame smacked her son on the head angrily. "And why am I hearing about this only now ? You dummy !"
"Aye I know, I'm sorry." Haru apologised, unapologetic. He wasn't happy. "Why are you hitting me ? It's no big deal."
"No big deal ? Do you think making a fool of yourself among the most reputable people of the village is no big deal ?" Retorted Hisame sarcastically. "I'll handle your gift. You smell. Go wash yourself and make yourself presentable. You have an hour."
"Alright."
During the awakening of the Dead Bone Pulse many bodily impurities were excreted out of his skin pores. He was indeed a bit dirty.
Jumping inside a warm bath, Haru washed himself clean before closing his eyes, meditating.
The scroll's instructions for the practice of the sensing skill came to his mind. It wasn't a difficult skill to learn in Haru's opinion, quite the opposite in fact as it would have not been suitable for branch children to practice otherwise.
But there was however a major factor that made practitioners of sensing unequal from the very beginning.
Talent and affinity towards yin release.
The sensing skill worked by releasing a yin chakra field in the surroundings. Yin chakra was formless, and was ineffective on its own if one attempted to create physical chakra constructs and most ninshu techniques.
But the chakra field which allowed the user to comprehend his environment mentally was a prime example of the unique capabilities of yin release.
Following the manual he memorised, instead of directly merging his mental and physical energies in his chakra system he focused solely his mental energy behind his forehead. As the concentration rose steadily, a small headache began to bother Haru.
A short while later, when the little headache became almost a painful feeling, Haru paused.
Normally when one would awaken sensory abilities for the first time, the higher the concentration of yin release chakra at this step the better the initial range of the sensor would be.
The capability to endure that yin release energy concentration was what defined one's sensory talent. Average initial ranges spanned from a few meters at the lowest to thirty to forty meters, and even fifty meters for the most gifted sensors wasn't that uncommon.
On the other hand, forcefully keeping the yin release energy build up ongoing in spite of the pain wasn't the smartest move there was either. Cerebral injuries were at stakes if one turned out to be unable to manage this substantial amount of energy during the release phase that came next.
Even though Haru didn't care much about sensing abilities with his Byakugan, he was determined to excavate his potential without neglect in all areas.
So after a short pause, the bathing white haired boy resumed his yin release concentration efforts.
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It's one AM here, I quite sure there are some mistakes out there as I published it on the spot.
Sorry there has been quite a mouthful of technical yapping yet again, I'll try to introduce the rest of these infos shortly so the story could advance faster in the future.
Shoutout to DaoistIJnsc, Romance_guy and Roger_Burgess who didn't relent in their stony support !
Love you guys :D Keep it up.