He thought so inwardly, but soon her composure returned. Katsuyu's voice steadied, calm again, though the air around them rippled faintly as she spoke.
"Even if it's truly Hagoromo himself you're going against," she said, "then I still can't proactively side with you in this form. He's still a creation of the human current, born of this world's flow. To act against that would mean acting against my own very nature."
Ryusei nodded quietly.
He had expected as much.
He understood right away what she meant.
Just like before, she didn't mind him using her fragments in battle or fleeing here if he had to, even against them.
But even if Hagoromo himself stood against him, she would also never directly interfere.
Not in her true form. Not even if that same ancient being was the one threatening his life.
Because, to her, he was still a being originating from the same mortal world as Ryusei, only from a much earlier age.
And she had long ago chosen never to interfere in that realm, perhaps not even by choice, but because the very design of her creation forbade it, woven into the laws that defined what she was.
Ryusei had realized it long ago: no matter how much of his ever-growing chakra reserves he poured into the contract, even when he could've theoretically summoned something far greater over time, she always capped what crossed over.
The versions that appeared were powerful, yes, but they never carried the same overwhelming natural energy or awe-inspiring presence that radiated from her true form.
It fit her nature perfectly: distant, unwilling to interfere, yet faintly curious and quietly passing fragments of herself into the world, as if to leave a trace without ever truly stepping into the conflict.
"But," she continued, and her tone deepened slightly, carrying rare firmness,
"I can still draw lines. If that old toad interferes directly against you in the future... then it becomes my concern. I'll warn him once. If he ignores that…"
Ryusei blinked at that, slightly caught off guard. "You'd actually go that far?"
She hummed lowly, a vibration passing through the ground beneath them.
"You forget, Ryusei. The three of us—the Toad, the Snake, and I—aren't gods. We're reflections of what this world values. His domain is balance, the serpent's is ambition and metamorphosis, and mine… is endurance through change. I don't resist what comes; I adapt until it fits. You're an anomaly this world hasn't learned to accept yet—so I will. That's my nature. And if he takes issue with that, then he takes issue with me."
She paused, the mist pulsing faintly around her. "So survive this trial, and I'll make sure that meddling frog never lays a shadow on you. Consider it my version of balance."
Ryusei stared at her for a moment, a small laugh escaping before he could stop it. "You're serious," he said quietly. "I don't know whether to be impressed or terrified. What happened to the lazy shut-in who only moved when begged?"
Her feelers twitched, faintly annoyed. "Even slugs have pride. Don't make me regret the sentiment."
He smiled faintly, shaking his head. Internally, though, he couldn't help wondering how exactly she planned to "warn" Gamamaru, and since when this giant, introverted otaku of nature had such sudden bursts of passion. Still, in his own dry way, he felt grateful.
"Then I'll make sure to live through this," he said lightly. "Wouldn't want you to waste that rare burst of motivation."
Katsuyu exhaled through the mist, her tone dry again. "Good. Because I don't give those out often."
Ryusei nodded, with a grin, and soon stopped at the edge of the basin without any further delay or fear.
The air had grown heavier here, thick enough to feel on his skin, humming faintly against his nerves.
He let out a slow breath, piece by piece, everything came off, his flak vest, boots, shirt, until nothing remained but the fabric around his waist.
The mist clung tighter now, reacting to the chakra pulsing under his skin.
Katsuyu's massive eye watched him in silence, the weight of it like a verdict.
Ryusei stepped forward.
The first contact burned.
The black water hissed where it met his foot, bubbles rising in slow, lazy bursts.
He didn't flinch.
He just kept walking.
Each step sank deeper, the acid licking higher, dissolving dead skin and pulling faint wisps of chakra from his body.
The heat was sharp but clean, like a blade scraping away everything that didn't belong.
He closed his eye briefly, listening to the faint echo of Katsuyu's pulse through the ground.
"Alright," he murmured quietly, more to himself than to her. "Let's see if nature's ready for me this time."
Then he stepped fully with his feet in.
The pool would swallow him whole soon, in a few seconds.
But he knew what came next. He was as prepared as anyone could be.
He had talked about it with Katsuyu many times over, studied it himself, watched Nagato endure it, and spent months preparing for this exact moment.
And he already believed that some of his long-built strengths gave him an edge over Nagato, more than enough, at least, to make success feel within reach.
But first, he admitted that to survive here, strength alone meant nothing.
The body couldn't overpower nature; it had to surrender to it.
The trick wasn't to resist but to let go completely, to dissolve piece by piece until what remained could rebuild itself through stillness.
That was the real meaning of the Slug Sage's path.
Using his own powers here, vibrations, boiling pressure, the inner gates, and even any deliberate chakra enhancement would be suicide.
Any attempt to fight back or exert will only speed up the corrosion.
The more one resisted, the faster the pool consumed.
Only the raw, unguarded body could endure this place.
That was why he'd spent the last few months perfecting his baseline physique, something he'd already been fortunately purposfully shaping for years, ever since the day he first woke up in this body.
Additionally, immense chakra reserves were essential, a vast well of life force just to withstand the corrosion.
Without it, even touching the black water would trigger instant cellular collapse. Thankfully, he also had it.
His strength here had to come from what he was, not what he wielded.
The black water punished interference.
It demanded a body that could adapt on its own, the way Katsuyu's tissue did, semi-fluid, self-healing, endlessly conductive to chakra.
The goal wasn't to endure the acid but to become part of its logic, to mirror its nature until the distinction vanished.
Most failed long before that.
The acid didn't just dissolve flesh, it devoured identity.
The forest didn't kill intruders directly; it absorbed them, piece by piece, memory by memory, until only echoes remained.
And those echoes never truly died.
They lingered in the pool's depths, whispering through every drop, hundreds of fragmented consciousnesses pressing against whoever entered.
Each one was a lesson in pain, screams, sensations, flashes of dying thoughts, assaulting the intruder's mind in waves.
To survive, one had to stay lucid enough to absorb those imprints without being replaced by them.
The body had to adapt, the mind had to accept, and the soul had to remain still.
Success here meant temporary self-erasure, trusting that you could dissolve and still remember who you were when it was over.
Fortunately, Ryusei's inner core, as well, his soul, spiritual power, willpower, and sheer tolerance for pain, was already tempered far beyond ordinary limits.
Another requirement, luckily, was quietly met.
The line between merging with nature and becoming nature vanished quickly once inside.
Only those who could find their center again after losing it completely would rise back up.
Ryusei had prepared for this part most of all.
His meditation training since transmigration had sharpened the balance between surrender and control.
His chakra reserves, already monstrous, would fuel his survival; his control, honed to precision, would prevent rejection.
However, through his research and experience, he already understood the precise kind of chakra control required here.
Too little control, and the acid would consume him instantly.
Too rigid, and natural energy would rebound, tearing him apart from within.
The balance required micro-adjustment in every heartbeat, yielding, absorbing, stabilizing, and reforming in rhythm with the forest's own pulse. His single Byakugan, in fact, could prove very invaluable here.
Every breath, every chakra thread, had to move with the same rhythm that beat beneath the earth.
That was why he came here, to match that rhythm, to stop being separate from it.
Ryusei gradually stepped deeper, the black liquid climbing past his knees, his waist, then his chest.
The first touch burned, not the sharp pain of heat, but a slow, seeping ache that sank straight into the bone.
His chakra stirred instinctively to defend him, but he forced it still, keeping his breathing steady.
He matched his pulse to the forest's rhythm, guiding every cell to yield, not resist.
The acid gnawed at his skin, his chakra coils trembled, and his vision blurred under waves of foreign memories pressing in.
Faces, screams, sensations of dying, echoes of countless others who'd failed before him.
He let them pass through.
Every instinct screamed to fight back, but he kept still, focused, adjusting the flow of chakra with microscopic precision.
His Byakugan flared faintly beneath the eyepatch, tracking the movement of energy through every part of his body, letting him see where the acid met his chakra, where resistance risked ignition.
His body shook, then steadied.
The pain didn't fade; it deepened, becoming rhythm instead of agony.
His chakra and the black water began to pulse together, like two hearts syncing in the same beat.
It wasn't easy. It wasn't meant to be.
But even as his skin dissolved and reformed, even as his breath turned ragged and the weight of death pressed closer, Ryusei endured.
Because this place wasn't killing him.
It was remaking him.
Hours passed in silence, broken only by the low pulse of the forest.
The pool had long since swallowed Ryusei whole, leaving no trace of him above the surface.
Only faint vibrations rippled through the black water, matching the steady rhythm of the land itself.
Then, at last, something shifted.
The surface trembled, first gently, then violently, as if rejecting what it could no longer consume.
A low hum built beneath the basin, followed by a burst of pressure that split the stillness apart.
The black liquid erupted upward in a surge of steam and mist, and from it, Ryusei emerged again.
His body gleamed faintly, steam rolling from his skin.
The changes were visible even in the dim light, his frame even denser, movements smoother, every motion precise but fluid, as if gravity itself had softened around him.
His chakra shimmered with a pale blue-green glow, a calm radiance that made the mist itself seem to breathe with him.
There was an otherworldly stillness in him that came from total harmony with the environment.
The forest no longer pushed against him; it moved with him.
Ryusei then entered his new active Slug Sage Mode, letting the forest's natural energy surge through him as he tested the full transformation he acquired for the first time next.
Faint lines of bluish-green light flickered beneath Ryusei's skin, soon tracing through his veins like liquid jade.
His eyes gained a soft, glass-like shimmer, reflecting ripples instead of glow.
The air around him moved in quiet waves, his chakra blending even more seamlessly and completely with the forest's rhythm.
He stood still, calm and steady, looking almost translucent under the mist, a being more fluid than flesh, as if nature itself had decided to keep him.
Katsuyu's immense form shifted from the shadows, her translucent bulk stirring the air.
One enormous eye blinked, glowing faintly.
"So, the human survived after all," she murmured. "And here I thought you'd dissolve into fertilizer like the rest."
Ryusei exhaled, the faintest grin tugging at his lips. "You sound disappointed. Admit it—you were rooting for me a little."
Katsuyu made a sound somewhere between a sigh and a low ripple through the soil. "Rooting? Hardly. I just didn't want to waste the effort of explaining your failure to Tsunade."
He chuckled quietly, rolling his shoulders, still adjusting to the strange weightless strength in his limbs. "Well, tell her the forest liked me. Guess I'm officially part of the scenery now."
"You're part of the mess, more like it," she replied, but her tone had softened. "I'll admit, though, the forest didn't reject you. That's rare."
Ryusei raised a hand, flexing it slowly as faint light pulsed beneath his skin. "It's not rejection if you learn to move like it. I didn't fight it—I listened."
Katsuyu's eye curved faintly, almost amused. "You always talk like someone who thinks he's figured out nature. Give it time; it'll remind you who's in charge."
"Maybe," he said, glancing at her massive form. "But for now, it's letting me borrow the throne."
She hummed quietly, studying him. "You humans never learn. But I'll admit, this one suits you. Not too loud, not too proud… adaptable. You might finally stop being so exhausting to watch."
Ryusei smirked. "Don't lie. You'd miss me."
Her voice vibrated softly through the ground. "You're the most tolerable chaos I've had in centuries. Don't let it go to your head."
He smiled faintly, stepping past her toward the misted clearing.
The pulse of the forest followed his rhythm now, slower, calmer, as if acknowledging its newest creation.
"Don't worry," he said over his shoulder. "I don't plan to dissolve again anytime soon."
"Good," Katsuyu replied, voice low and almost fond. "I'd hate to start liking you."