Four months later.
The early morning air over the training ground was still crisp. Sengoku arrived at his usual secluded spot, his eyes systematically sweeping the perimeter. Only after confirming he was entirely alone did he reach into his oversized ninja pouch.
He pulled out a crude, heavy iron sphere roughly the size of a handball. Its surface was a patchwork of rough metal plates, welded together with obvious amateurish difficulty. It looked like scrap, but it represented four months of grueling labor and the total depletion of his meager savings. It was one of four working prototypes he had managed to construct.
He called it the Hover Drone. The name carried his vision of a weapon that could float silently, reposition on a whim, and deliver a fatal, unexpected strike.
The reality, however, was still severely lacking.
Sengoku placed the drone gently on the sand. He raised his hands, focusing his chakra. Ten thin, pale-blue chakra threads extended from his fingertips, seamlessly sinking into the crude metal shell to interface with the internal mechanics.
'Rise.'
The iron sphere shuddered. Lifting off the ground, it wobbled briefly before stabilizing in the air, hovering precisely one and a half meters above the sand.
Sengoku locked his gaze on a half-buried, dead tree stump twenty meters away. With a subtle manipulation of his fingers, the Hover Drone slowly rotated in the air, aligning its heavily perforated front end with the target.
His index finger twitched sharply.
Click.
The internal spring mechanism snapped. A dense, high-pitched whistling instantly tore through the quiet morning.
Thwack-thwack-thwack!
Twenty thin steel senbon erupted from the sphere in a highly concentrated, fan-shaped spread. The vast majority of the needles slammed deep into the dead wood, clustered tightly together in the center of the stump.
But the moment the volley ended, the hovering iron sphere went completely dead. Bereft of ammunition, it became useless weight. Sengoku severed the chakra threads, and the hollow shell plummeted to the sand with a dull thud.
Sengoku didn't celebrate. He walked over to the stump, meticulously extracting his reusable senbon from the wood, before returning to pick up the fallen iron shell.
The lethality was acceptable. The clustered spread was dense enough to guarantee a hit, and if coated in poison, a single needle breaking the skin was all it took.
But the flaw was glaring.
"Single-use," Sengoku muttered, his voice heavy with frustration.
It was a fatal bottleneck. In a life-or-death battle, no enemy would give him the several minutes required to manually reload the firing chambers. Furthermore, his physical stamina and non-existent budget meant he couldn't simply carry a massive swarm of fifty drones to compensate.
The design had to evolve.
As Sengoku stood frozen in the sand, staring down at the empty metal husk and trying to mentally restructure the internal mechanics, a voice suddenly broke the silence.
"A very ingenious concept."
The voice was mild and completely unthreatening, yet it caused Sengoku's heart to hammer against his ribs. He had checked the perimeter. He hadn't sensed anyone.
He spun around instantly, slipping into a defensive stance.
Standing a few paces away was a young man, perhaps around twenty years old. He wore the standard flak jacket of a Sunagakure Jonin, but his aura was entirely out of place for the brutal village. He exuded a calm, grounded presence. His eyes held a mix of genuine curiosity and deep appreciation.
Crucially, the Jonin wasn't looking at Sengoku; his gaze was locked onto the crude iron sphere in the boy's hands.
"Using chakra threads not just as a mechanical trigger, but to achieve stable, mid-air suspension… the thought process is incredibly unique," the young man said smoothly, taking a few steps forward as if discussing the weather. "However, once it expends its payload, it becomes dead weight. Have you not considered a way to extend its operational lifespan in the field?"
Sengoku's eyes narrowed. This stranger had deconstructed his entire design and identified its fatal flaw from a single glance.
Seeing Sengoku's intense, guarded reaction, a flash of surprise crossed the young man's face, quickly melting into an apologetic smile.
"My apologies, I didn't mean to startle you. I was merely passing by, and my attention was caught by your… novel little creation." His eyes remained fixed on the Hover Drone, burning with the pure, unadulterated fascination of a craftsman.
"Who are you?" Sengoku asked, his tone carefully neutral but laced with underlying caution. A Jonin with such a mild temperament was a glaring anomaly in the Hidden Sand.
"Monzaemon," the man replied simply. He said it without arrogance, yet carried an undeniable, quiet confidence. His attention snapped right back to the iron ball. "Did you build this yourself?"
Sengoku's mind raced. Denying it was pointless; the Jonin had already watched him test it. Furthermore, someone with this level of mechanical insight could be a valuable resource. Lying would only close off a potential avenue of knowledge.
He gave a curt nod. "Yes. It's a prototype I've been experimenting with."
"Suspension via chakra threads, aiming for maximized lethality in a single burst… a fascinating approach." Monzaemon analyzed the core philosophy of the weapon without an ounce of judgment, offering only objective critique. "But the drawback is severe."
The words perfectly echoed Sengoku's own grim assessment. Sengoku remained silent, but the subtle tightening of his grip on the metal shell confirmed the Jonin's deduction.
"The path you are attempting to walk is highly unorthodox," Monzaemon continued, finally looking up to meet Sengoku's eyes. "Miniaturization and extreme specialization. To compensate for the lack of traditional puppet utility, you will need a terrifying level of control precision, or an immense amount of time to refine the design to make it viable. It will not be easy."
He paused, his expression turning thoughtful as he offered a crucial piece of guidance.
"Perhaps you should adjust your perspective. Don't solely focus your engineering on perfecting the launch mechanism." Monzaemon smiled faintly. "Why not first consider… retrieval?"
"Retrieval?" Sengoku echoed instinctively.
Seeing the spark of sudden realization ignite in the boy's eyes, Monzaemon's smile widened slightly. He offered no further explanation.
With a polite, acknowledging nod, the young Jonin turned and walked away, leaving Sengoku alone with his thoughts.