[Konoha Year 39 – Two Years after the Outbreak]
Time had not been kind to Sayo's fragile constitution. While other two-year-olds in Sunagakure were beginning to run across the dunes, Sayo remained a prisoner of his own biology. His skin retained a sickly, translucent pallor, and his breathing was a constant, shallow rasp. In the harsh climate of the Land of Wind, a single gust of grit-laden air could send him into a week-long spiral of fever and coughing.
Unable to leave him with neighbors and unwilling to let him out of his sight, Sharyu transformed the Fourth Maintenance Squad's workshop into Sayo's primary world.
The squad operated out of a colossal, vaulted cavern carved into the bedrock of the village. It was a subterranean cathedral of industry, sheltered from the sun and steeped in a unique atmosphere: the sweet, resinous scent of planed cedar, the heavy musk of machine oil, and the sharp, metallic tang of Chakra-Conductive Metal.
In a dry, windless corner of the forge, Sharyu had constructed a "safe zone" for his son. Using discarded but sturdy puppet limbs, he built a waist-high fence, lining the interior with soft blankets and stockpiling fresh water. It was a playpen built by a shinobi—shielded from flying sparks and heavy footfalls, yet offering an unobstructed view of the workshop floor.
For the first few months, Sayo spent most of his time asleep, his body exhausted by the mere act of existing. But as he grew, his waking hours became a silent, obsessive vigil.
His eyes—dark, intelligent, and housing the soul of a thirty-year-old lead engineer—devoured the mechanics of the shinobi world.
The maintenance bay was a hive of frantic activity. Ninja in grease-stained gray coveralls—men and women who were more mechanics than assassins—swarmed over puppets that had been scorched by Fire Style jutsu, snapped by Earth Style, or mangled beyond recognition by Konoha's traps.
Clang! Clang! A heavy hammer reshaped a warped titanium-alloy joint. Screeech— A precision graver skimmed along a Chakra-channel groove, clearing out carbonized residue to restore energy flow. Whirr… A manual lathe spun as a craftsman turned a fresh length of desert ebony into a ball-and-socket shoulder.
The air was a symphony of sawing, filing, and low-intensity technical debates. Sayo watched it all with the predatory focus of a scholar. To the other workers, he was just a sickly child staring blankly at scraps; to Sayo, these were not scraps. They were components of a logical, albeit mystical, system.
He watched an technician clamp a ruined puppet arm to a bench and pry open its casing. Sayo's mind immediately began mapping the internal transmission—the hair-thin Chakra Wires acted as both data cables and fiber-optic actuators. He watched the man use tweezers to splice a severed line until the wooden fingers suddenly twitched with a soft, mechanical click.
His father, Sharyu, was the undisputed master of this domain. His rough, scarred fingers were uncannily steady. By touch alone, he could gauge the micron-level wear on a bearing; with a single glance, he could identify a clog in a Chakra Circuit.
As Sayo observed, the memories of his past life as Liu Yu flooded back with agonizing clarity. He had spent his previous life among CNC blueprints, automated production lines, and PLC logic. His hobby had been the "soul of the machine"—the satisfaction of a perfectly milled part, the curl of a wood shaving, the cold gleam of a steel assembly. His dream had been the ultimate engineering romanticism: a pilotable, bipedal mobile suit. A Gundam.
In his old world, the laws of thermodynamics and energy density had made such a dream impossible. But here?
Chakra... it's essentially a high-density, biologically generated wireless power source, Sayo's mind raced, translating shinobi lore into engineering data. Those etched sealing runes? They're printed circuit boards designed for energy conduction.
He saw a flaw in a gear train: The lubrication is primitive; the desert grit is grinding it down. A double-lip dust seal would solve that in an instant.
He saw a limited range of motion in a leg joint: Why use a simple hinge? A universal joint or a constant-velocity coupling would increase the tactical flexibility by forty percent.
A blazing, manic thrill ignited in his small chest. In his past life, he lacked the "impossible" materials. Here, they had metals that responded to human thought and energy that defied gravity.
Could I... combine my knowledge of automation and mechanical physics with these puppet arts? His gaze drifted to a dark corner of the forge where "Obsolete Models" stood—structures that were mechanically sound but deemed too slow or clunky for modern warfare. To the Suna ninjas, they were trash. To Sayo, they were Mobile Suit Prototypes.
He stretched out a tiny, trembling hand toward the sparks flying from a nearby grinder.
His body was weak, and his start was abysmal. But he was surrounded by machines and the power to move them. In the eyes of the two-year-old Sayo, the light of a visionary engineer finally flickered to life—a light that knew only one goal:
I am going to build a god out of wood and iron.