"Ordinary Ninjutsu involves using the internal energy of the body—combining one's physical and spiritual energy to create 'Chakra,' which then serves as the energy source for the technique."
"Whereas Sage Art, on this foundation, introduces and harnesses a third type of energy existing in the external natural world, between heaven and earth, which is what we call 'Natural Energy.'"
"The special Chakra produced by utilizing these three energies is what we previously referred to as 'Sage Art Chakra,' and the techniques or moves performed with this Chakra are known as 'Sage Art.'"
"Doing so can greatly enhance previously used Ninjutsu, Genjutsu, and even Taijutsu…"
Senju Mori sat cross-legged on the ground, quietly listening to various explanations about Sage Art. The voice came from a giant slug, more than ten times larger than a Tailed Beast, with a body length of several hundred meters.
This was a unique sight only found within this secret realm; even Senju Hashirama, whose Chakra reserves were unparalleled in the Ninja World, could not fully summon the Sage of Shikkotsu Forest's true form to the outside world.
Looking across the entire history of the Ninja World, perhaps only the Six Paths Sage, who once served as the Ten-Tails' Jinchuriki, could possess such immense power.
After finishing his affairs in Uzushiogakure, Senju Mori returned to Konoha and eagerly began his training in Sage Mode.
During a time when research into Hashirama Cells and other projects were unlikely to make progress in the short term, learning Sage Mode and mastering Sage Art was undoubtedly his most effective way to improve his personal strength.
Through the Reverse Summoning Jutsu performed by the Sage of Shikkotsu Forest, Senju Mori quickly arrived at one of the three great summoning holy lands, a special natural secret realm known as "Shikkotsu Forest."
The air here was so viscous it seemed to drip water, and each breath was permeated with an ancient life force and a faint sourness.
As far as the eye could see were impossibly large animal skeletons. Senju Mori was unsure of their specific origin; perhaps they were ancient giant beasts drawn by the abundant Natural Energy.
But after their deaths, the remaining bones formed pale, mountain-like structures, making up the fundamental framework of this world.
Warm, steaming spring pools were scattered throughout, forming countless waterfalls of various sizes due to elevation differences, bringing subtle sounds as decoration to this tranquil world.
What appeared to be a beautiful, ethereal scene, however, contained deadly dangers.
The liquid forming the waterfalls and pools was not ordinary clear water, but an acidic liquid containing dense Natural Energy, appearing in a faint pale yellow color.
Should any foreign creature fall into it, it would be dissolved into stark white bones in an extremely short time.
Occasionally, bubbles would rise from the bottom of the pool, releasing a thin mist with slight corrosive properties when they burst.
In the distance, there was a lush forest.
Compared to the bone-white forest and pale yellow acid pools, it exuded a different kind of vitality and vigor.
But in reality, it was a special type of fungus that only grew in this secret realm, emitting a unique green phosphorescence. When stepped on, it would slightly sink and generate a soft ripple.
And at the center of all this was the impossibly large true form of the Sage of Shikkotsu Forest.
It lay quietly prostrate, its eyes at the tips of its two tentacles looking down. Its body, covered in blue and white patterns, pulsed rhythmically, like the constantly beating heart of this world.
Its very existence was like a part of the earth itself, emanating Sage Art Chakra as vast as the ocean and full of warmth, making Senju Mori deeply feel his own insignificance.
"Lord Mori, please now use the mucus I secrete to sense and try to absorb the Natural Energy from the outside world."
As a renowned place of inheritance in the Ninja World, among the three great summoning holy lands that are the primary instructors of Sage Art, Shikkotsu Forest could be said to have the best service attitude.
The Sage of Shikkotsu Forest spoke very politely, and her voice was pleasant, with an ethereal and otherworldly feeling.
Although he had long understood this giant slug and knew that she had a habit of addressing her contractors as "Lord."
But when this mountain-sized creature truly appeared before him, speaking in a gentle voice completely disproportionate to her size, and calling him "Lord Mori,"
Senju Mori still felt a strong sense of incongruity.
The Sage of Shikkotsu Forest is an extremely unique life form in the entire Ninja World. She was born in an era before Ōtsutsuki Kaguya's arrival and has lived for over a thousand years.
It is no exaggeration to say that her existence is even more ancient than the ancestors of the Senju Clan.
At this moment, Senju Mori was bare-chested, and a small slug, only a palm's width, slowly crawled on his body, its cold and soft body continuously secreting transparent mucus.
Senju Mori silently closed his eyes, fully sensing the Natural Energy permeating the surrounding air.
Initially, his perception only encompassed a chaotic darkness and the flow of his own Chakra.
But with the aid of that miraculous mucus, the "truth" of the world gradually unfolded before his "eyes"—countless tiny, living-like specks of light floated in the air; these were the ubiquitous Natural Energy.
The earth beneath his feet, the surrounding acid and fungi, and even the entire internal space of Shikkotsu Forest, all emitted a powerful and prolonged life pulsation, like a giant breathing organism.
Shikkotsu Forest was already a special secret realm with an extremely dense natural environment. With the help of the slug's mucus, a peculiar sensation arose, and Senju Mori felt as if countless "air currents" were rushing towards him.
As these "air currents" surged into Senju Mori's body, strange patterns began to rapidly spread across his face, his eyes gradually bulged, and his skin subtly began to turn transparent… Just as practicing Sage Art at Mount Myōboku results in toad-like features, and practicing Sage Art at Ryūchi Cave causes snake corneas to grow.
The Natural Energy absorbed through Shikkotsu Forest's method also caused Senju Mori's body to transform in the direction of a slug.
However, this unusual physical change quickly disappeared.
The Sage of Shikkotsu Forest's ethereal voice resonated once more, carrying a reassuring tone.
"Excessive absorption of Natural Energy will cause the body to mutate, gradually stiffen, and eventually become a part of Shikkotsu Forest."
"But please do not worry, my clones will ensure your safety and absorb any excess Natural Energy in a timely manner."
"Next, please try to guide this absorbed Natural Energy within your body and mix it with your spiritual energy and physical energy, achieving a precise 1:1:1 balance to create Sage Art Chakra…"