Yuzuru Uchiha opened his eyes to a withered forest shrouded in miasma.
There was no sign of life anywhere. The ground, swamp-like and stagnant, was littered with white bones.
Even the sky seemed veiled in a layer of gray fog, hazy and indistinct.
"Lord Yuzuru, Lady Tsunade, please follow me."
The small slug perched on Tsunade's shoulder spoke gently.
Yuzuru nodded and withdrew his gaze.
Straight ahead stood a massive cave. Above its entrance, three large green characters were carved into the stone.
Damp Bone Forest.
The cave ran deep, and after walking for a while, the light gradually dimmed.
However, relying on his powerful perception and the vision of his Sharingan, Yuzuru could still clearly make out his surroundings.
The deeper they went, the more beautiful the scenery inside the cave became.
Colorful stalactites and stalagmites intertwined, forming all manner of strange and vivid shapes.
From time to time, a steady "drip, drip" echoed in his ears, while the strong scent of acidic liquid continuously assaulted his nose.
"Lord Yuzuru, the liquid on the ground is acidic. Please be careful."
Hearing the slug's reminder, Yuzuru nodded lightly and casually asked, "Why are there so many bones here?"
The small slug on Tsunade's shoulder immediately explained, "Although Shikkotsu Forest is remote, over the past several thousand years, many people and animals have accidentally wandered here."
"After learning of the power of Senjutsu, they all wanted to master it. But aside from Hashirama Senju, not a single one succeeded. They all died here."
Yuzuru nodded.
Learning Senjutsu required drawing natural energy into the body, which was an extremely dangerous process.
In the original story, when Naruto Uzumaki trained at Mount Myōboku, it was mentioned that failure would result in being turned into a toad statue.
Kabuto Yakushi had even modified his own body into that of a snake just to learn the Sage Arts of Ryūchi Cave.
Judging from this, Shikkotsu Forest's Senjutsu were likely no easier to cultivate.
Walking ahead, Tsunade couldn't help but remind him, "Yuzuru, learning Senjutsu is extremely dangerous. Don't force yourself."
Yuzuru smiled and reached out to hold Tsunade's hand, saying confidently, "Don't worry. I'll be fine."
For others, cultivating Senjutsu might be perilous, but for someone with a Sage Body like his, it shouldn't be too difficult.
After all, if even someone with his physique couldn't succeed, then no one else possibly could.
They walked a bit farther before the space suddenly opened up.
Bright sunlight fell across his face, causing Yuzuru to squint slightly.
Before him stretched a vast, open grassland that extended beyond the horizon.
A gigantic slug, nearly a hundred meters tall, lay sprawled across the grass, its entire body radiating a languid aura.
"Lady Katsuyu."
Tsunade greeted it and briefly introduced Yuzuru.
The Slug Sage spoke gently, "I already know your request. I will now pass on the method of cultivating Shikkotsu Forest's Sage Arts to you."
As it finished speaking, a small slug split off from its body and crawled onto Yuzuru's shoulder.
"Lord Yuzuru, from now on, I will assist you in learning Sage Arts."
Yuzuru clasped his hands toward the Slug Sage. "Thank you."
The Slug Sage replied in a soft voice, "There's no need for thanks. But cultivating Sage Arts is extremely dangerous. If you die, don't blame me."
After speaking, the Slug Sage lay down on the ground and closed its eyes under the sun.
Seeing this, Yuzuru couldn't help but think to himself, 'If the Slug Sage could transform like the White Snake Sage, it would probably be the textbook image of a shut-in woman.'
"Yuzuru, I'll be leaving now. Be careful."
"I know."
After seeing Tsunade off, Yuzuru found a spot at random and sat down cross-legged.
Compared to the shinobi world, the natural energy in Shikkotsu Forest was overwhelmingly denser.
It seemed the three great sacred lands being able to pass down their legacy from the era of Ōtsutsuki Kaguya to the present truly wasn't something to underestimate.
Still, his current strength wasn't enough to dominate everything, so he could only suppress these thoughts and pretend ignorance.
After all, in the original story, although Shikkotsu Forest and Ryūchi Cave had little direct portrayal, Mount Myōboku alone revealed enough.
It could be said that without the forces of Mount Myōboku, represented by the Great Toad Sage, working behind the scenes, Ōtsutsuki Hagoromo and Ōtsutsuki Hamura might not have succeeded in sealing Ōtsutsuki Kaguya at all.
As he was thinking, the small slug's voice sounded by his ear.
"Lord Yuzuru, the most important thing in learning Sage Arts is maintaining a calm and steady mind."
"While absorbing natural energy, you must remain completely focused. If you fail to properly balance natural energy and the chakra within your body, there's a risk of your body exploding."
The small slug went on to explain many precautions regarding the cultivation of Sage Arts.
Among them, the most dangerous stage was absorbing natural energy into the body and fusing it with chakra.
If anything went wrong, even the gods couldn't save you.
"In short, try to first sense the presence of natural energy."
"If you can't even feel it, then no amount of worry will help."
The small slug smiled gently.
Over the years, countless people had wanted to learn Sage Arts.
But most couldn't even sense natural energy, let alone absorb it into their bodies.
Yuzuru nodded slightly and closed his eyes, adjusting his breathing.
Very quickly, streams of energy drifting through the air appeared within his perception.
"So powerful, so vibrant!"
Yuzuru murmured.
Compared to chakra refined within the human body, the natural energy produced by nature was clearly far stronger.
Drawing such power into the body—no wonder it was so dangerous.
Taking a deep breath, Yuzuru cautiously guided the surrounding natural energy into his body.
Before long, he completely relaxed.
His Sage Body absorbed the natural energy without any resistance, and there was no sign of it running out of control inside him.
'As expected of a Sage Body—truly powerful.'
Yuzuru marveled inwardly and began circulating the natural energy through his body according to Shikkotsu Forest's cultivation method.
At the same time, he combined it with his internal chakra in a fixed proportion.
Just like when drawing energy into his body, he encountered no difficulty at this stage either.
Under his powerful mental strength, the creation of senjutsu chakra proceeded flawlessly.
After a while, Yuzuru exhaled a breath of turbid air and slowly opened his eyes.
Seeing him exit his cultivation state so quickly, the small slug immediately comforted him, "Lord Yuzuru, even if you failed, it's alright. Sensing natural energy isn't easy. Many people spend months or even years on it."
"I'll stay by your side and help you sense natural energy."
Hearing this, Yuzuru shook his head. "No. I've already succeeded."
"Eh?!"
The small slug exclaimed in delight. "You sensed natural energy this quickly? Lord Yuzuru, you truly are a once-in-a-millennium genius."
Yuzuru shook his head again. Faint black markings appeared at the corners of his eyes.
"What I mean is… I've already successfully gathered senjutsu chakra."