Ashina tilted his head slightly, his tone carrying curiosity.
"So then let's put the Gates to the side, they are obviously not something you can touch any time soon… So wouldn't you want to learn a proper taijutsu form? There are countless schools, countless disciplines in this world. Even the art of fists and movement has its structures. Surely one of them could serve you."
Kimimaro only gave a thin grin in reply.
He raised his right hand, palm up, and let his chakra flow.
Slowly, deliberately, a pale sliver of sharpened ivory broke through the flesh, a bone spike unfurling from within like a blade sliding from a sheath.
He twirled his wrist lazily, the narrow weapon cutting the air with a faint hiss.
"That's my problem," he said dryly. "This body came with something… special. Something my clan decided made me a monster. They locked me away, afraid of me, until I slipped out not long ago."
He swung the bone lazily, almost playfully, with that faint grin still on his lips.
"So you see, old man, no kata, no traditional taijutsu form will ever fit me. I'll have to build my own way of fighting. Guess what this is, if you can."
Ashina's soul-flame flickered as he watched.
His first reaction was silence, then a low hum.
"…A bone… weapon? No… not a weapon. Your own skeleton? Pulled out at will?" His tone sharpened, shifting from shock to fascination. "So it is kekkei genkai. Not earth release. Not any mutation of medical chakra. Something I've never once seen in my life."
He paused, as if weighing the implications.
"To twist your own body like that, and yet remain standing without collapse… that means your tissues, your marrow, your very chakra coils are reforged into something unnatural. Not mere adaptation. Inherited. A bloodline limit, then."
Kimimaro smirked faintly, rolling the bone spike back into his palm until it slid away, and skin sealed over smooth once more.
"Exactly. A gift so rare my clan feared it. They called it a curse, a madness. Locked me in a cell instead of teaching me. But I see it for what it is. Power. And power doesn't bow to kata or tradition."
Ashina let out a low, almost grudging chuckle.
"…You may be right. Whatever that is, no textbook taijutsu form would serve it. Only a man willing to carve his own path could wield such a grotesque gift. Perhaps, boy, it suits you more than you realize."
Kimimaro let the grin fade, his voice turning sharper, deliberate.
"Actually, this is the reason I crossed the sea at all. Why did I come here, despite my age? Why I gambled on these ruins."
Ashina's eyes, dim and spectral, narrowed with interest. "Your bones… and the Uzumaki? What kind of connection could there be?"
Kimimaro flexed his palm, and another spike of ivory slid free, longer this time, glinting in the dying light.
He didn't stop there.
He turned his wrist, and another bud of bone pressed under his skin at the forearm, threatening to pierce out.
His tone stayed calm, casual.
"I can make more than small spikes. I can tear out ribs, a spine, even my whole forearm into blades. I could make weapons ten times larger, harder, sharper, multiplied. My estimates say that I can. But…" His eyes shifted, the grin thinning. "There are risks. I know it."
Ashina, who had walked the earth for more than a century and lingered in spirit for two more decades, immediately guessed something.
"…Your body may heal in the short term, yes. I saw it, no blood spilled, the wound sealed instantly around the spike. That means your flesh is designed to accommodate such tearing naturally, to repair itself as you pull bone after bone. But no matter how well the body patches, what of the long term? You are afraid of what toll that will exact, boy?"
Kimimaro's eyes were half-lidded. His tone was cool. "That is exactly what I fear."
He tapped the bone once, then let it withdraw back into his skin seamlessly.
"I've always been cautious. Any unnatural gift like this… there's always a price. This is shinobi life, isn't it? Every forbidden power takes something in exchange. You gain, and you pay. That's the balance. I've always wondered what price this one demands."
Ashina gave a dry, grim hum. "Smart boy. You are right. And I think I know. The more you injure yourself, the more your body is forced to create. But every time the body replaces what it loses, something of the original essence goes with it. Piece by piece, the foundation crumbles. You make new material, but lose the old truth of yourself. A slow decay."
Kimimaro's pupils tightened, his mind snapping into sharp focus.
'That's it,' he thought. 'That's the disease. That's why the original me rotted from inside.'
For the first time since transmigrating, he heard words that matched his own past-life theory.
The ancient patriarch, without ever hearing of modern biology, had described telomeres and cellular attrition as if he knew it firsthand.
Kimimaro almost shivered.
Yes. The more your cells divide, the more data is lost.
The more "errors" creep in.
Shortened telomeres.
Lost information.
Breakdown hidden deep.
The original Kimimaro had butchered his own body constantly.
Tearing out bones again and again for Orochimaru's orders.
Strapping himself in grotesque inner bone armor.
Even pulling out his entire spine.
He had been killing his own cells with every performance.
No wonder his body collapsed before he ever reached twenty.
Kimimaro clenched his fist.
'That was the truth. The fool killed himself in installments.'
And it wasn't just him.
His mind jumped to others.
'This was exactly why Hashirama died relatively young, too. Not age. Not poison. Not enemy blades. He simply overused his legendary regeneration. In that battle with Madara, and all his life, he burned through himself until nothing was left. Regeneration isn't free. It eats lifespan.'
His thoughts quickened, sharp and cold.
'Tsunade proved it, too. Her constant regeneration shortened her life until she was an old crone under the disguise of fake youth jutsu. She traded years of life for each scar healed.'
Regeneration isn't life force.
They're opposites.
Life force is longevity.
Regeneration is patchwork.
Uzumaki lived long because of their life force, not their healing.
Senju were similar, their bodies robust, their chakra vast.
But only Hashirama had that alien regeneration, tied to his Wood Release and chakra that bound tailed beasts.
That wasn't Senju.
That was something else, some God Tree mutation through Ashura's soul shaping his body.
It made him inhuman.
Kimimaro took a long breath, steady.
'And me. My body also regenerates abnormally well, especially from the damage caused by my own bones from the inside. That's why I can even use this kekkei genkai at all. But the cost is obvious. Every spike, every rib, every grotesque weapon torn from myself, it shaves years away. It hollows me. That's why the original me fell ill. Why he died young. It wasn't a disease, it was slow suicide.'
His emerald eyes narrowed.
'That's why from day one, since I woke in this body, I knew. If I want to live, if I want to rise higher than anyone else, I can't use Dead Bone Pulse recklessly. I need to master it. Restrain it. Turn it into a tool, not a death sentence.'
'Otherwise, I'd just be repeating the same tragedy. And I have no intention of being another fool who dies young, discarded and forgotten.'
Meanwhile, Ashina's voice broke through the quiet like a sharp wave again.
"Wait, this still doesn't explain why you came here of all places. Why the Uzumaki ruins?"
His tone wasn't accusatory, but it was edged with bewilderment.
By now, he already understood what Kimimaro truly sought: a way to use that monstrous gift of his without killing himself young while living in great misery.
But he had no clue what link Uzumaki heritage could have with bone and marrow.
Ashina's eyes narrowed, thinking deeper.
His spiritual aura seemed to churn as he ran through every scrap of his knowledge.
Then, suddenly, his voice snapped in realization.
"Yes… of course! A simple answer: Yang Release! That's it!"
His tone rose, almost triumphant, before it dropped again into a mutter.
"But how did you know the Uzumaki were particularly good at this? No, this is why you pressed me on medical arts before. That's why you emphasized them with such interest. I wondered why a boy like you would fixate on that. Now I see."
Kimimaro's lips curled into a grin, sharp and amused. "Exactly. If I can't afford to tear bones from the inside endlessly, then the solution is simple. I have to make more of them from the outside." He continued, letting his voice flow calmly and confidently.
"I bring out only the smallest amount of 'material', bone spikes, thin as needles. Then I let Yang Release do the rest. I expand them outward, shape them with chakra programming, and refine them into larger and more useful and powerful weapons and techniques. That way, I don't have to destroy myself for raw material. My kekkei genkai manipulates bone cells naturally, that's Yang's domain, obviously. The problem is…"
He paused, expression tightening. "…I've tried. And no matter how I push, it's slow. Too slow. That means I'm missing something, the true essence of Yang Release. I have the bloodline affinity for it, but affinity isn't mastery. I need that accumulated knowledge of your great Uzumaki clan, from hundreds of years, which my own clan and background obviously lacked. Medical ninjutsu is a part of that plan. I could use it to train my Yang Release more naturally."
Ashina's spectral brows furrowed, his mind chewing on the logic.
Kimimaro continued, eyes half-lidded, tone dry but laced with conviction.
"From the beginning, this was the only answer. Use Yang Release to generate new cells externally instead of forcing my body to regenerate them internally, killing me from the inside. More chakra spent, yes. Active work, yes. But no fatal erosion of the original essence."
His palm flexed, and a thin shard of bone pushed through the skin like a needle.
"For example, instead of ripping my entire spine out to make a whip and gambling my life on growing a new one, I make a pinprick opening. Let a sliver of bone surface. Then lace it with Yang Release, sprinkle it with programmed chakra, hand seal or no seal at all, and let it bloom into something far larger."
Kimimaro grinned faintly, eyes glinting green, "Simple. Efficient. Sustainable."
Ashina stared at him for a long while, his voice finally coming low and thoughtful. "…You're a monster, boy. But perhaps a cleverer one than even your own blood could ever imagine."
In fact, Kimimaro had some other questions to ponder in his mind at that point.
Why was it that Ashina could grasp nearly this truth so clearly, yet Kabuto and Orochimaru, two of the most, if not the most, scientifically and medically gifted shinobi of the original series, never seemed to act on it?
The answer was obvious. Of course, they understood it. But they had no idea how to use Kimimaro without burning him out.
So, they chose the simpler path: exploit him as long as possible, then discard him when the body inevitably broke down.
To them, he was a weapon with an expiration date, nothing more.
They may even have believed that if they tried something like Kimimaro's current approach, shaping bones externally through Yang Release training, through medical applications, instead of ripping them out endlessly, he would end up weaker, less deadly in the short term.
So they never told him.
They wanted a tool, not a student.
On top of that, they likely didn't recognize that Kimimaro was himself a Sage Body descendant, naturally gifted in Yang Release, more than most could ever dream.
Or, perhaps they realized all of this only when it was already too late, when his body had deteriorated beyond the point of being a viable vessel for Orochimaru, so at that point, they didn't bother to change anything.
After all, in the original story, Hashirama's death was never openly explained as the consequence of his own overuse of regeneration.
That sort of knowledge lived on the bleeding edge of shinobi medical and research overall understanding. Maybe they weren't even sure.
After all, this world's biological scientific level rarely pushed beneath the basic cellular level, and this fell under that.
Ashina, however, didn't need microscopes or experiments.
He reached the truth through centuries and more of intuition, through patterns learned from watching a thousand years of Uzumaki history, through the kind of insight only sealing arts could give, a field that demanded a mind as sharp as any scientist's.
In his way, Ashina might not be much less brilliant than Kabuto or Orochimaru intellectually.