At the Land of Rivers frontline main camp, the atmosphere was thick with the heavy, cloying scent of oxidized blood, bitter medicinal herbs, and a palpable feeling of "Systemic Exhaustion." The news that the Sandstorm Squad had suffered a "Near-Total Wipeout" did not cause much of a ripple in the village's primary directories. In this massive meat grinder of a war, the deletion of a single squad was a statistically insignificant event. But for Sayo, standing amid the bustling, chaotic camp, it felt like his internal "Network" had been severed. He was the last active node of a shattered process.
Captain Iryō had been moved to the Severely Wounded Partition. His right wrist had undergone emergency "Hardware Reconstruction" by the senior military doctors, saving his life, but the hand and the accompanying ninja career had reached its definitive "End-of-Life" (EOL). Shiori was arranged to rest in the low-priority directory, but the mental trauma was far more difficult to debug than physical wounds. She often woke up screaming from "Uchiha-induced" nightmares, her eyes still reflecting the terrifying scarlet light of the Sharingan.
One dead, two incapacitated. The once high-performance Sandstorm Squad was now a "Corrupted File," with only Sayo remaining at full operational capacity.
However, the Third Great Ninja War was currently hitting its Peak, and Sunagakure had no time for any unit to wallow in a Grief. Within hours of his return, an order was pushed through Elder Chiyo's adjutant.
"Chunin Sayo!" The adjutant's expression was as cold as a system prompt. "Given your demonstrated Medical Ninjutsu capabilities and the current surge in frontline casualties causing an extreme Shortage in the Medical Squad, you are temporarily requisitioned. Report immediately to the Field Hospital for 'Biological Repair' duties! This is a high-priority task. Do not delay!"
The order was a "System Reallocation." Sayo silently accepted the command, his 30-year-old soul, the mind of Logan, understanding the cold logic of the battlefield. He visited the unconscious Iryō one last time, then stood by Shiori's bed. She was staring at the tent ceiling, her mind still struggling with the Genjutsu.
"I'll be back once the repair cycle is complete," he whispered to her, then resolutely turned and walked toward the rear of the camp, where the sounds of suffering were most concentrated.
The Field Hospital was less of a hospital and more of a "Massive Collection Point" for damaged hardware. Tents stretched out toward the horizon, filled with casualties that defied description: severed limbs, chemical burns from Mist toxins, internal organ ruptures from Iwa's Earth Release, and the "Fried Circuits" of those hit by Kumo's lightning. Exhausted Medical Ninjas moved through the rows like overworked processors, their faces showing a "Numbness" born of excessive workload.
A Suna Medical Jonin, his eyes showing signs of "Sleep Deprivation" and his voice a hoarse rasp, simply verified Sayo's "Healing Technique" credentials before assigning him to a tent designated for "Moderate System Damage."
"You know how to run the Healing script, right? Focus on 'Surface Repairs', stopping hemorrhages and stabilizing vital signs. Mark the 'Fatal Errors' and pass them to the senior doctors! Hurry up! Our latency is killing people!" The Jonin spoke with the speed of a high-frequency trader before vanishing into the next tent.
There was no time to adjust, no time for sentimentality. Sayo stripped off his dust-covered combat vest, sanitized his hands with a "Chemical Flush," and immediately threw himself into the work.
He crouched in front of a Chunin whose abdomen had been sliced open by a Konoha Wind Release "Vacuum Wave." A soft, emerald-green light glowed from Sayo's hands, the visual output of the Mystical Palm Technique. His chakra-threads, refined by years of puppet-making and Natural Energy control, acted like microscopic "Soldering Irons," precisely closing blood vessels and re-stitching the cellular matrix.
Initially, he was a little rusty, his "Code" needing a few cycles to warm up. but soon, the calm, ruthless logic of the engineer and the precise chakra-control honed by the Body Tempering Furnace took over. He treated wounds with a "Zero-Tolerance" for error, calculating his chakra consumption with a precision that bordered on the supernatural.
He found that by treating the human body as a "Complex Machine," he could optimize the healing process. He wasn't just "healing"; he was "Patching the Hardware." Day after day, he encountered hundreds of different "Errors":
Sword Wounds: Physical breaches in the chassis.
Poisoning: Malicious chemical injections that corrupted the internal cooling system (blood).
Lightning Burns: Over-voltage damage to the nervous system.
He was no longer just learning theory from the Suna Academy's scrolls. He was placing his hands upon the raw "Source Code" of life. He sensed the texture of every muscle, the "Conductivity" of every meridian, and the "Flow Rate" of every artery. His understanding of human anatomy accumulated at an exponential rate. He witnessed the "Total Deletion" of life in some, and in others, he managed to "Rollback" the damage just before the system crashed for good.
The Field Hospital became his new battlefield, one without the Mirage or the Iron Sand, yet equally demanding.
Only during the extremely rare "Rotation Breaks" could he find a quiet corner to "Defrag" his mind. Physical exhaustion was handled by the Natural Energy already present in his system, but the "Mental Cache" was overflowing with the negativity of the dying. At the same time, he realized a critical "Bottleneck": even with the foundation of the Natural Energy Body Tempering Furnace, he was still limited by his "Proximity to the Source." To stay at 100% capacity, he needed a mobile solution.
A thought began to crystallize in his mind, an engineering "Requirement" that had to be met: Miniaturization.
The original Body Tempering Furnace was a massive metal cylinder, a "Server-Rack" solution. The Natural Energy Furnace back at the village was a "Local Network" solution.
"I need an 'Edge Computing' device," Sayo muttered, pulling out a note-scroll and his drafting pen.
Using the dim light of a flickering oil lamp, he began sketching a new "Hardware Architecture." His goal was a miniature Natural Energy Body Tempering Furnace that could be carried as a "Wearable."
His mind returned to the concept of the "Watch" from his previous life as Logan. The "Dial" could serve as the "Control Interface" and the "Monitoring HUD." The "Case" could integrate a microscopic Spirit Siphoning Seal and a high-density Natural Energy conversion unit using the Sandaime's Iron Sand as a magnetic stabilizer. The "Strap" would act as the "Energy Output Contact Points," continuously and slowly "Broadcasting" Natural Energy into the wearer's radial artery, effectively acting as an "External Battery" that purified fatigue and optimized the biological OS in real-time.
This was an extremely bold "Build," involving the limits of Sealing Technique, Materials Science, and "Micro-Manufacturing." But as Sayo looked at the blueprints, his eyes didn't show exhaustion; they showed the "Challenge Gleam."
"If I can miniaturize the furnace," Sayo thought, his pen flying across the paper, "I won't just be patching my own body. I can create 'Standard Issue' units for the village. I can fix the 'Hardware Gap' between the Sand and the Leaf."
The wailing sounds of the Field Hospital continued to rise and fall in the background, the "Background Noise" of a world at war. But in that quiet corner, under a stack of medical reports, the design for the "Mirage Chrono-Furnace",the first piece of wearable tech in the Ninja World was quietly being compiled.
The "Biological Repair Cycle" was about to move from "Manual Patching" to "Automated Maintenance."