Katsuyu's massive form shifted faintly, sending shallow tremors across the ground. Her voice rolled through the mist, patient, dry, and faintly amused.
"So, he really lives after all..." She murmured. "I suppose proper congratulations are in order then, red-haired human... However, your species honestly does have a habit of surviving things you shouldn't, just look at Ryusei, for example."
Ryusei crossed his arms, half-smirking. "You sound almost proud, Katsuyu. But then again, since he's your legitimate newest follower, maybe it's time you pass down some techniques as his teacher. He's part of your lineage now, after all."
Her enormous eye tentacles blinked once, the movement deliberate and slow.
"Techniques?" she echoed. "You know me, Ryusei. I don't hand out scrolls or fancy doctrines like those other two overgrown menageries. And considering the number of survivors, in the past, you can count on with your one or two hands, there isn't much of a sample size to build from anyway." Her tone turned faintly amused, like she was scolding a child for asking something obvious.
"If he wants to learn, he'll do it the same way he survived that pool, by adapting. Shikkotsu doesn't teach. It offers only potential, nothing more."
Ryusei let out a quiet sigh, his tone carrying that familiar teasing edge again.
"Still as lazy as ever…" he said with a faint grin. "But you could at least point us in some useful directions. You know yourself and your powers and essence better than anyone else, after all, at least. And you know I'm planning my own attempt in a few months, perhaps already, and I'd rather have a clearer idea of what there is to gain before I start dissolving then. You also know how I am; I like taking old attributes, especially anything involving my favorite slug, and turning them into something new, stronger, and even more useful. However, creativity takes time, so do us both a favor and give me a little head start."
A ripple of faint amusement rolled through the basin. "Very well," Katsuyu said.
"You've probably already noticed it yourself with that eye of yours, at least to some extent, so don't pretend otherwise, Ryusei..." Katsuyu said, her calm voice carrying that deep, resonant weight.
"But fine, I'll lay it out for you clearly once this time. So listen closely and ask questions, both of you, because I'm not a teacher and I won't repeat myself."
"His 'passive', 'baseline' body has already been rewritten to an extent as you saw, even without entering or holding active Sage Mode. That's what makes Shikkotsu different from the others. It doesn't lend power, it remakes you. It reshapes the body so it always contains its essence, allowing you to enter that state more easily and remain in it far longer. And that's only part of it, since there are other traits and attributes unique to this place alone in both active and passive states to a different degree. All of it, in some way, comes from, and is possible thanks to what this land has absorbed over centuries, too, the echoes, remnants, and lingering essence of every being that failed before."
"So then," Ryusei said, his tone half-curious, half-practical, "I already know what the usual, 'universal' Sage Mode buffs look like, but what about yours? What exactly are the unique traits of your region, its natural energy, and its... philosophy, so to speak? What do we actually gain from it, both passively and when it's fully active? Or is it the same power, just amplified during activation?"
"First, you need to understand..." Katsuyu began, her tone slow and heavy, like something ancient reminding children of simple facts, "that your structure doesn't just toughen, it rebuilds itself inside those black pools. It becomes something closer to my own. That's where the new traits take root. More fluid. More adaptive. You already have a decent idea of what that means, Ryusei, you've been using my power long enough to guess it before I even say it now."
"Every cell becomes capable of altering itself freely," Katsuyu said. "Your body can liquefy, reform, divide, merge, replicate, conceal, or disperse damage without ever truly breaking. How far that goes depends on your grasp of my philosophy, your finesse on those specific paths, and how much chakra or natural energy you channel, especially when you enter active Sage Mode."
Ryusei was genuinely impressed then; this was far beyond anything he had fully anticipated. Even if much of it sounded "auxiliary," he knew that in the right hands, his hands, it could become monumental, and "the sky was the limit". And this was no less of a game-changer for him than all Eight Gates. Not to mention how well that kind of arsenal could go with his current abilities.
Therefore, a faint, almost greedy grin immediately curved his lips as he said again, "So, for example, Nagato could become practically indestructible from now on, just like you are, at least to some degree, only with enough training, mastery, and exploration? Since, of course, you've had a few thousand years of refinement ahead of people like us, and this is your own essence we're talking about, so to speak, we won't get there and become like you completely; we are not the same 'category' objectively. But, still very convenient, to say the least."
"Not indestructible, never that..." Katsuyu corrected, her tone carrying that slow, grounded patience of someone who had seen centuries pass. "Resilient. Pain becomes temporary. Damage becomes instruction or even leverage. The body learns from harm instead of suffering it from it, like bamboo that bends but never breaks, and water that yields yet always remains. That must be first."
Nagato immediately got some inspiration and flexed his fingers, faint ripples of pale cyan light moving beneath his skin. "I can feel it..." he murmured. "It's like my body isn't resisting anything anymore. Just calmly absorbing, dispersing… reshaping."
"Exactly," Katsuyu said. "That's the essence of it. Also, even now, those special acids your body gained from the pools work in tandem with your chakra, constantly dissolving and repairing microscopic damage on its own. It's self-healing that needs no seals, no focus, not even awareness. The more you fight, the faster and stronger that cycle becomes."
Ryusei nodded thoughtfully. "So, like Hashirama's highest form of regeneration, even above mine; perfect, automatic recovery with zero shinobi techniques?"
"In a sense," she replied. "But his came from something older, a fusion of this art and another, far deeper lineage. That's why it was so strong. But that is only one aspect. With time, you can refine it, shape the acid's behavior for offense as well. The potential here also lies in how well you innovate from it… not just inherit it."
Ryusei smiled faintly. "Then what about the Sage Mode itself? If all this is just the passive state, I can only imagine what the active one's like. Go on, humor us a little, feed our imagination."
Katsuyu's tone deepened, a low vibration echoing through the air. "Okay, first, when he activates it, the natural energy doesn't coat him; it circulates through him way more. His cells merge temporarily with the surrounding flow, turning him into a living extension of Shikkotsu's network. That's why it lasts longer than any other Sage Mode. It's not borrowed power; it's a homecoming."
Ryusei's eyes narrowed slightly, already calculating. "So, unlike Myōboku's temporary harmony or Ryūchi's aggressive control, this one's about total integration. He doesn't use the energy, he becomes it."
"Precisely," Katsuyu said. "That's why the duration is nearly indefinite, only limited by your own chakra. The body no longer resists or consumes nature; it coexists with it. That also means fewer external markings. The transformation happens fully beneath the skin."
Nagato looked up, faint light reflecting in his golden eyes. "Then what can I do with it the fastest, first in the beginning?"
Ryusei glanced at Nagato, then at the slug, half-grinning when he noticed the faint droop in Katsuyu's massive eyelid.
"The question, Nagato," he said with deliberate amusement, "also isn't about what this gives you, it's what you'll make of it, where you are the most comfortable? Katsuyu's getting pretty bored and lethargic from all of the speaking, so let me save her the trouble."
Katsuyu's low rumble rolled through the ground. "I'm listening, Ryusei. Impress me before I fall asleep."
Ryusei chuckled softly, hands behind his back as his tone grew analytical. "The foundations are simple. Your regeneration now borders on rebirth. You can liquefy parts of your body to evade attacks or reform instantly, or disperse incoming damage across your structure before it ever lands. Your chakra circulation's perfect, no waste, no imbalance. Poisons, chakra corrosion, and even genjutsu interference get filtered out automatically. You've basically become your own cure."
Katsuyu hummed, sounding faintly pleased. "Not bad. You actually paid attention and have great intuition."
"And it doesn't stop there," Ryusei continued. "Your chakra transmission's changed too. I predict that you could eventually share your healing, chakra, and even your senses, with allies through contact, or eventually, through proximity alone. Think of it as being part of Katsuyu's network. You'll feel everyone linked to you, like organs in one body. You should be pretty familiar with such matters already."
Nagato tilted his head. "So… my reach extends even without control?"
"In a way," Katsuyu replied. "Your field of influence becomes alive. Every cell resonates with the world around you. The more natural energy you draw, the wider it spreads. In Sage Mode, that awareness becomes almost planetary. You'll feel every shift in moisture, pressure, and breath. You won't see through eyes anymore, you'll see through everything."
Ryusei's grin deepened. "Its sensory perks are even better than other from the other Sage Regions. Immortality through adaptation. You don't overpower the world, you outlast it until it bends around you."
Katsuyu's massive feelers twitched, her tone slow and deliberate. "That's the essence of my region. The toads seek balance through cooperation. The snakes dominance through evolution. But the slugs in nature, or better said, I, survive through transformation. That's why we endure. The forest doesn't kill what already belongs to it."
Ryusei gave a quiet nod, then added, "As I understood it, your cells now act like fluid conduits. Semi-liquid, chakra-conductive, able to shift density, soft to absorb, solid to strike, liquid to evade. The acid your chakra produces dissolves foreign chakra and toxins automatically, almost like digestion. You adapt faster than you take damage."
Katsuyu interjected, "And with training, you'll divide your body, just like me. Fragments linked by chakra, sharing one will. Destroy one, and it reabsorbs into another. Multiplicative, not disposable."
Ryusei's smirk widened. "So, a proper evolution of clone techniques, without the fragility of shadow clones. Finally."
"Exactly," she replied. "Each piece is you, fully aware, fully capable. That's how I heal armies at once. You'll learn that in time."
Ryusei's tone grew curious again. "And your 'armor' you mentioned to me once before in the passing?"
"That's the slige Sage Slime Armor, I use..." Katsuyu said simply. "A membrane of dense chakra around your body. It blocks or dissolves attacks, even Sage Jutsu. It can absorb impact, store it, and release it back as force. Every strike you take could become a counterattack if you will it. You humans should be able to eventually acess it during the active usage of my region's Sage Mode."
Nagato's fingers twitched slightly, faint ripples moving outward through the mist, trying something else out of the sudden.
Ryusei's Byakugan flickered beneath his patch, tracking every vibration, and eventually saying in surprise. "And you can seemingly even pull natural energy mid-battle to refill stamina, or absorb ninjutsu directly through contact. An organic Preta Path. Good catch, Nagato."
Katsuyu gave a faint hum of approval. "Exactly. But only if you maintain the rhythm. Shikkotsu rejects greed. Take too much, and you dissolve again."
Ryusei nodded slowly, thoughtful. "So it's defensive, adaptive, sensory-based, with near-limitless endurance, but not much in raw destruction."
"Correct," Katsuyu said, her voice softening to something almost fond. "You won't level mountains like the snakes or the toads, or kill with a punch or a roar. But you'll outlive those who try. Nature itself refuses to kill its own creation."
Ryusei laughed quietly, more to himself than her. "And that, I think, is exactly why I like it."
Katsuyu's eye half-closed in amusement. "Of course you do. You've always preferred power that waits instead of shouts."
Nagato looked between them both, his tone faintly wry. "So what you're saying is… we can't die easily anymore."
"Exactly," Ryusei said, eyes glinting faintly. "But we can do far more than just live. Now we reshape what living means."
Katsuyu's rumble deepened again, approving and faintly proud. "Good. Then maybe you'll both soon prove worthy of the name 'Shikkotsu Sage' before the century ends."
Eventually, Ryusei tilted his head slightly, again thoughtful. "Then, if I'm not wrong," he said, "the two main chakra affinities this Sage Mode uniquely operates on, unlike the other ones, should be Yang and Water, right? Yang for vitality, growth, and regeneration… and Water for adaptability, conduction, and acid-based chakra manipulation. Combined, that would work like some organic adaptation, every attack or injury becoming a trigger for evolution or counter instead of damage."
Katsuyu's massive eye blinked once, a faint ripple moving through the ground beneath her. "That's correct. You learn quickly, as always. The fusion of those two is what sustains Shikkotsu's philosophy. Once again, you don't resist the world, you reshape with it."
Ryusei smiled faintly. "Roger that."
Inside, though, his thoughts moved faster.
Already, he was charting new routes, mentally connecting these powers to his old and existing arsenal, already considering possible entirely new technique prototypes unique to the Slug Sage Mode, other hybrid applications, and long-term integration paths.
'Hagoromo, Gamamaru, Konoha… I won't fade quietly,' he thought, a faint grin tugging at his lips.
'I may not have dozens of centuries carved into my being like you do, not even a fraction of your time, but like this slug, I endure.'
'Every bit of pressure you force on me will become my fuel. The more you try to crush me, the stronger I'll grow. That's a promise.'