Kimimaro's grin widened. "So, tell me more about the Yang Release then, old man."
Ashina's spirit let out something between a scoff and a hum.
"Bold brat… Fine. Listen carefully. For once, the Yang Release is not just 'healing chakra' like the various medical shinobi would have you believe."
"Their most common, so-called Mystical Palm is just one crude application, medical Yang chakra, a general mending technique. It patches flesh, restores balance, but that's barely scratching the surface."
"Yang Release is one of the two primal halves of chakra. Remember this: all chakra is born from both spiritual and physical energy at the same time. However, the ratios could vary."
"Yin comes from the spiritual, the shaping power of the mind. Yang comes from the physical, the vitality of the body."
"When the balance tilts more toward one or the other, you create Yin Release or Yang Release and their techniques."
"This is why some clans are more talented in one or another, depending on whether their talents are more physical or spiritual energy type. All kinds of jutsu could come from that."
He let the words settle before continuing.
"Yang is growth. The power to vitalize, to amplify, to give form life. It can mend wounds, invigorate tissue, or even bring the inanimate into motion. So, when you say your bloodline manipulates bone cells, yes, it reeks of Yang Release. So your clan is like mine in general."
Kimimaro's eyes glinted faintly as he listened, focused like a blade.
He laid out some exercises plainly next.
First, breath and circulation.
Drawing chakra in with every inhale, flooding it into the body with every exhale, until it felt like the blood itself thickened with energy.
Then, small tests, pressing chakra into a shallow cut, not to close it instantly, but to strengthen the tissue around it, knitting it together more durable than before.
"Growth isn't speed," Ashina said flatly. "It's endurance."
The next was laughably mundane, nourishing a seed with chakra until it sprouted. "Not forcing it open," Ashina warned, "but feeding it until it chooses to grow. You'll learn restraint that way."
Kimimaro's mouth twitched at that one.
A child with godlike ambition, reduced to babysitting sprouts. Still, he didn't argue.
Then came something more fitting.
Channeling Yang directly into muscle or bone until they felt heavier, denser, like the body itself thickened under the weight.
Releasing, resting, then doing it again.
Permanent change, slowly carved into flesh.
Finally, Ashina spoke of stillness, lying down at night, imagining marrow glowing, cells dividing in rhythm with his chakra.
A visualization, a trick to align the brain with the body's natural cycle.
Ashina's eyes narrowed. "But remember this. Yang is life. Push too far, and it burns you hollow. Even life, in excess, is poison."
Kimimaro listened in silence.
Some of it he dismissed immediately; the seed exercise, for instance, sounded more like a farmer's work than shinobi training.
But when Ashina spoke of densifying bones, Kimimaro's attention sharpened.
That was a direct path forward.
His Dead Bone Pulse wasn't meant to rip his body apart blindly.
It was meant to be refined, built up.
He nodded slowly. "I'll do them all. Even the seed."
His grin sharpened faintly. "But don't expect me to talk kindly to plants."
Ashina huffed through his nose, something halfway between a laugh and a scoff. "Good enough."
But then Ashina added, almost like an afterthought, "In fact, those exercises are just prerequisites. The real purpose is to prepare you to learn medical ninjutsu quickly, and to experiment, on animals if you wish, and eventually even on yourself. Your clan left you nothing, no notes, no manuals, no inheritance. You're on your own regarding bone growth."
"And the most direct, universal application of Yang Release is precisely the most mundane thing people overlook: medical arts. That's why your instinct was correct when you pressed me about it first. So from here on, we'll fold medical training into your daily practice as well."
However, all of a sudden, Ashina's voice carried another spark of realization."…Wait. Of course. Healing bone fractures. That's it."
Kimimaro tilted his head, eyes narrowing slightly.
Ashina went on, almost to himself.
"To heal them, the body accelerates cell division, stacks new material, and strengthens the frame. If I dig into the master scrolls I sealed with myself, I may still have some specialized medical jutsu designed for that exact process. Yes… It's not just mending, but stimulating growth in a controlled way. If we start there, it might suit your case better than anything."
Kimimaro's expression steadied after hearing that, but there was a rare glimmer in his eyes.
Gratitude. Not the shallow thanks he sometimes offered, but genuine relief about this crucial, eventual early next step for him.
He once again made a silent vow.
Whatever Ashina truly planned for his eventual return, he didn't know yet.
But if the old man ever asked, he would give it his all to find him a suitable vessel.
"All this time I've been groping in the dark, piecing scraps of logic together on my own. And now you tell me… that the answer I was hoping for might already be in your hands, old man."
"I had nothing before this, as you said. No scrolls. Not even any verbal teachings. My clan left me blind, not understanding even their most potent ability."
However, Kimimaro soon grinned again while jokingly saying.
"But, now you're finally speaking my language, old man. Healing bone fractures… to me, that's not treatment. That could be the first step of weapon-forging. You're finally telling me exactly what I wanted to hear the most this entire time."
Ashina almost flinched at the boy's tone.
Gratitude wrapped in a predator's smile at the end.
Yet the ripple it left in his spirit felt strange, goosebumps, pride, something close to the thrill of teaching again.
For a heartbeat, he saw himself not as a failed patriarch chained to a stone, but as a master guiding a disciple.
"Hmph. Don't look so pleased with yourself. This is still only theory," Ashina muttered, trying to bury the flicker of pride.
"But… yes. It seems your instincts were right all along. You were right to come here first."
Kimimaro gave a dry chuckle. "So even the great Ashina Uzumaki admits I was right."
Ashina's face twisted, half-annoyed, half-smiling despite himself. "Insolent brat…"
They spent the rest of the day circling through ideas, Ashina overseeing Kimimaro's first exercises and critiquing his form, while Kimimaro absorbed every word with unnerving focus.
Finally, when the boy slipped away to train in silence, Ashina lingered, feeling something he hadn't in decades.
Kimimaro soon wrapped up the day.
His new schedule was already mapped out in his head.
In no particular order: elemental immersion for water and earth, chakra control drills geared toward ninjutsu, external sensory exercises to sharpen his field, physical conditioning for body and coil density, spiritual energy cultivation through meditation, internal perception for checking his own system, Yin Release exercises for his planned "genjutsu immunity," and, most importantly, Yang Release exercises.
Those, in time, would transition into medical release training, and at the very core of it, the crucial bone-cell generation practices.
His days would be packed to the brim from now on. But that was fine. Better than fine. At least he wouldn't be left to rot in boredom.
Besides, he had something far better than scrolls or teachers from rumor; he had Ashina Uzumaki himself. A Peak Kage, overseeing every step of his growth.
What more could he ask for? In his heart, Kimimaro made a quiet vow: he would repay this old ghost, if he could, somehow, someday. Not with shallow words, but with actions.
Soon, Kimimaro might even ask Ashina to give him a basic introduction to fūinjutsu, at least the fundamentals, before moving on to the wider study of jutsu-shiki.
After all, fūinjutsu was just one branch of that greater discipline.
He was already prepared for it.
Back in that coastal Fire Country town, he had also brazenly stolen some scrolls and ink.
The sooner he began, the better.
In fact, seven years old was probably the perfect age.
He even doubted whether Minato had started as early, since Jiraiya likely didn't teach him until later.
Kimimaro also believed he had an edge that others lacked.
His enhanced mind, sharpened by transmigration, and his knowledge of modern formal sciences from his past life gave him a unique perspective.
To him, fūinjutsu and jutsu-shiki were essentially natural laws, ways of programming chakra, shaping it through rules and systems.
What the shinobi of this world treated as mysterious arts, he understood as models, abstractions, formulas.
Hand seals, for example, were nothing but fast, battlefield-ready jutsu-shiki, mental shortcuts that the brain could be trained to execute instantly.
But in reality, anything could serve as a seal medium, as long as the brain had been conditioned to use it.
For more enduring or powerful effects, one needed preparation, inscribing longer arrays, etching them into paper, metal, or stone.
Chakra was programmable.
Jutsu-shiki was the coding language.
And with the right formulas, the results could stretch into the impossible, such as Minato's Flying Raijin, a technique so absurd it almost broke the common sense of this world.
However, Kimimaro hadn't come here with fūinjutsu as his main goal. But it was still one of the most useful tools a shinobi could have, worth picking up as soon as possible.
Seals could be applied to anything, storage, suppression, barriers, explosives, or even something as grand as binding tailed beasts.
And Kimimaro fully intended to one day take some of their 'juicy' chakra for himself. After all, if Nagato and Obito could do it, why couldn't he?
Not to mention, sealing was the only real counter to Edo Tensei.
If Orochimaru or Kabuto began fielding Edo Tensei resurrected armies in the future, a shinobi without fūinjutsu would be helpless.
So, even if he never reached the absurd levels of someone like Minato, it was still an indispensable skill to have in his arsenal.
Still, that wasn't the real reason he had crossed the sea and risked himself at such a young age. The true purpose was Yang Release, the key to solving the flaw of his own bloodline.
A shinobi's path had to be built on their strongest foundation, and for him, that was the Dead Bone Pulse. Shikotsumyaku.
If he didn't solve the sickness tied to it, then everything else was meaningless.
He knew that Sage Body clans had always been gifted in Yang Release.
It was the natural extension of their vast physical energy.
But Toneri's clan had long vanished on the moon, the Kaguya were worthless barbarians, and the Senju self-destructed and now decayed inside dangerous Konoha.
That left only the ruins of Uzushiogakure.
And here, fate had greatly rewarded him.
Not only had he found exactly the key he sought, but he had also stumbled into something far greater.
Ashina himself, with centuries of Uzumaki insight, knowledge, and techniques, firsthand.
A jackpot that not even he could have fully calculated beforehand.
He smirked faintly at the thought.
He also wasn't like those idiotic xianxia protagonists in his past life's webnovels, charging blindly into fights and trouble.
No, his plan was simple and disciplined.
Ideally, he would stay hidden here for years if he had to, to maximize his advantage to the utmost.
Build a base of power, sharpen his edge, and only then step into the wider world, at the right moment.
At the exact point when his canon knowledge of this world's "plot" would give him the maximum return.
Patience first. Timing second. Power third.
As sleep crept over him, another thought took root.
The ultimate evolution of his bloodline.
The form he dreamed of.
The All-Killing Ash Bones.
Perhaps one of the most, if not the most, powerful of the certain-kill techniques ever shown in the original series.
If it connected clean, it started to deteriorate at a molecular level, rapidly disintegrating the victim and reducing their bodies to nothing more than a pile of ash, hence that name.
He wasn't delusional enough to even dream of something like the Tenseigan right now; that was too far, too alien, for him now.
But the Ash Bones felt like a logical peak of the next few years, perhaps.
A natural progression.
Just as the Sharingan could evolve into the Mangekyō, perhaps the Shikotsumyaku could evolve into the feared Ash-Killing Bones.
The logic and all kinds of similarities were there.
It even tied to what he remembered from the canon timeline.
Itachi's illness, for instance.
In truth, was it not the same root cause as his own?
Overuse of lingering Ōtsutsuki genes inside fragile human vessels.
Itachi burned his soul out for Konoha.
The original Kimimaro burned his body out for Orochimaru.
Both were proof.
These bloodlines could evolve, but if abused, they consumed the vessel.
Kimimaro felt that his Yin Release training might be crucial in deciding whether he could awaken the All-Killing Ash Bones in the future.
After all, to the eye, or at least Kimimaro's, its manifestation looked less like pure Yang chakra of the ordinary Dead Bone Pulse and more like a fusion of Yin and Yang together in some fashion, the so-called even more mystical Yin–Yang Release, rather than any ordinary expression of Yang alone.
If he could, he would truly stand among the monsters of this world.
No, more than that, he would become a very unique, lone existence at the top. The pinnacle of the Kaguya bloodline, the one to drag it out of ridicule and into the light of terror.
That was Kimimaro's last thought as his eyes closed.
The ruins around him were silent.
Tomorrow would be the first real step.