[Konoha Year 41 – The Temple of the One-Tail]
Sayo mastered the fundamentals of Fūinjutsu with a speed that bordered on the unnatural. The runes and principles that seemed like obscure occultism to others became a systematic architecture under his analogical reasoning. Bunpuku taught him with increasing depth, his mood shifting into a complex blend of pride and a faint, lingering worry about the destiny of a child gifted with such an intellect.
One afternoon, Sayo was using a twig to copy a Composite Sealing Formula into the dust of the temple floor, trying to understand the conversion logic between three intersecting energy nodes.
"Here, the velocity of the energy reflux is too high; it will cause a structural collapse in the main circuit," Bunpuku said softly, leaning over the drawing. "You must integrate a buffering 'Vortex' rune to dissipate the momentum."
Sayo nodded, preparing to modify the sketch.
"Hmph, a Vortex Rune? Inefficient!" Shukaku's signature raspy voice cut through the air. "Why not just use a reverse 'Repulsion' field to bounce the energy back? Simple and crude! You humans love making simple things complicated!"
Sayo paused, his twig hovering over the dust. "A Repulsion field? What kind of rune structure is that? Grandpa Bunpuku hasn't mentioned it."
"Hmph! Your current Sealing Techniques are primitive! So much has been lost!" Shukaku's tone carried a heavy weight of ancient superiority. "In the beginning, the ways we manipulated energy were far more varied than the 'broken baskets' you draw today!"
"The beginning?" Sayo seized on the term. His engineer's mind was always hungry for history—the "legacy data" of the world. "What was it like back then?"
Bunpuku opened his eyes, about to speak, but then sighed and remained silent. He knew that some histories, when told by an eyewitness, carried a weight of truth that no scroll could replicate—even if that witness was a creature of pure malice.
"The beginning?" Shukaku's voice became distant, saturated with a millennium of bitterness. "Back then, this world wasn't the desolate hellhole it is now. Especially this land."
"This area?" Sayo looked out the doorway at the eternal, oppressive yellow sand. "It's been a desert since the dawn of time, hasn't it?"
"Desert?! Bah!" Shukaku grew agitated, the air in the temple growing hot. "Before I was even born, this place wasn't a garden, but it wasn't this! There were trees! There was water! It could have sustained life as well as the territories of the Slug or that old fox, Kurama!"
Sayo was stunned. The Land of Wind... was once fertile?
"Then... what happened?"
"It was that woman!" Shukaku's voice flared with primal rage. "The woman from beyond the heavens—Ōtsutsuki Kaguya!"
The name struck Sayo's mind like a high-voltage discharge. Fragments of half-remembered lore from his past life—thumbnails from videos, snippets of web novels—coalesced. The Progenitor of Chakra. The Final Boss.
"She planted a damned tree in this soil!" Shukaku roared. "That tree was a parasite! It drank the energy of the entire world! The earth withered, the rivers dried up, and the very life force of the planet was stolen to grow a single fruit! This land, our land, was the first to be bled dry!"
Sayo's pupils constricted. Planting a tree... absorbing planetary energy... He recalled the term: The Divine Tree. As an engineer, he visualized it as a massive, biological vacuum, strip-mining the ecosystem of its fundamental energy.
"And then?" Sayo's voice was dry.
"She ate the fruit and became a god! But that only brought more trouble!" Shukaku snorted. "Then came her 'good sons'..."
"The Sage of Six Paths... Hagoromo Ōtsutsuki?" Sayo blurted out.
"Oh? You actually know the old man's name, brat?" Shukaku sounded momentarily surprised. "That's right! The old man and his brother! They fought their mother until the heavens cracked! That was true destruction!"
Shukaku's voice carried a rare note of awe. "I wasn't born until the old man split the Ten-Tails apart, but I heard him speak of it. That battle shattered mountains and caused the continents to sink! This land, already dying because of the tree, was finished off by the shockwaves of their war. The topography was altered, the aquifers were severed, and all that remained was this endless, drifting sand. It was the fault of those 'gods'!"
A heavy silence fell over the temple. Only the flicker of the oil lamp remained, illuminating Sayo's shocked face.
Everything clicked into place. The poverty of Sunagakure, the harshness of the Land of Wind—it wasn't a natural occurrence. It was the environmental scar of a mythological war. The ancestors of chakra hadn't just brought power to the world; they had committed an act of planetary-scale ecocide.
Sayo felt a shiver. The ground beneath him wasn't just sand; it was the ashes of a murdered ecosystem.
Bunpuku finally spoke, his voice weary. "Ashes to ashes, Sayo. The sins of the past have become the grit in our eyes today. What Shukaku says is largely true. This desert is a wound that has never healed."
Sayo looked down at his half-finished seal. Compared to the power that could drain a planet, these runes seemed insignificant. Yet, they were the key to control.
A thought, bold and nearly arrogant, took root in his mind: If the desert was caused by the destructive drainage of energy... could it be reversed through the exquisite, constructive guidance of energy?
It was a dream as vast as the dunes themselves.
Shukaku grumbled a few times and fell into a brooding silence, retreating into the depths of the seal. Sayo, however, remained wired. He looked out at the horizon, his gaze penetrating the rock walls. He was no longer just looking at a village; he was looking at a "broken machine" that spanned a continent.
And he was an engineer.