Sengoku unrolled the second scroll.
The contents of Wind Release: Wind Cutter were exponentially more complex than the Great Breakthrough. The diagram detailing the chakra meridian pathways was intricate, demanding that the user compress wind-natured chakra to its absolute limit, shaping it into an invisible, razor-sharp blade.
Sengoku rapidly memorized the convoluted sequence of hand seals and the borderline draconian requirements for chakra control. This jutsu wasn't a simple expulsion of energy; it required gathering force to a hyper-condensed point, meticulously molding its shape, and maintaining that fragile structure during an attack.
He began his first attempt. His hand seals were slow and deliberate, carefully guiding his chakra to flow and compress exactly as the scroll dictated.
He could feel the wind chakra gathering at his fingertips, but wrestling it into the ideal form—a blade as thin as a cicada's wing and sharp enough to cleave stone—was maddeningly difficult.
His first few attempts ended in immediate failure.
His best effort occurred only after completing the hand seals and viciously swiping his arm forward. It produced a sharp whistling sound, slightly more piercing than normal airflow, and left a shallow scratch in the sand. It was a far cry from the lethal, severing blade described in the text.
Subsequent attempts yielded even less; the chakra simply unraveled and dispersed at the critical moment of shaping.
Sengoku stopped his movements and frowned, clearly sensing his bottleneck.
The issue wasn't a lack of chakra reserves, nor was it flawed hand seals. Rather, his fundamental understanding of the wind's inherent "sharpness" was too shallow. More importantly, his current chakra control lacked the microscopic precision required for such advanced shape manipulation.
Forcing himself to practice further would only waste time and drain his reserves to no avail.
Decisively, Sengoku rolled up the Wind Cutter scroll and tucked it away. If his current control was insufficient for the jutsu, his immediate priority was to drastically elevate his foundational shape manipulation.
He had already mastered tree climbing. Water walking was impossible; Sunagakure was a desert, and attempting to practice chakra control on quicksand was practically a death wish.
He needed a method that pushed chakra shape manipulation to its absolute limits.
As he stood in the quiet training ground, he sank into deep thought. Suddenly, a dusty fragment of memory surfaced from the depths of his mind: a scene of a white-haired sage teaching a blonde boy. A swirling water balloon, a tough rubber ball, and finally, a dense, glowing blue sphere of terrifying, concentrated energy resting in the palm of a hand...
'The Rasengan.'
An A-rank, seal-less jutsu. The absolute, unadulterated pinnacle of chakra shape manipulation.
The training process itself was the most rigorous, effective crucible for chakra control ever devised. Furthermore, the three-step training method—the water balloon, the rubber ball, and the final sphere—was perfectly structured. Each step directly targeted the core of his current weakness. Once mastered, it wouldn't just solve his training bottleneck; it would provide him with a devastating trump card.
Sengoku weighed the logistics. Even as impoverished as the Hidden Sand Village was, simple children's toys like balloons and rubber balls had to be available somewhere.
His path forward was set. He secured his ninja pouch and walked out of the training ground, intent on gathering his materials.
Over the next few days, Sengoku used all his free time between academy classes to scour the village's obscure general stores and market stalls. He quietly accumulated exactly what he needed: a handful of thick rubber balls and a small bag of standard balloons.
However, he did not return to the academy training grounds. Instead, he relocated his practice to the absolute privacy of his dilapidated stone house.
He needed total isolation. If a first-year academy student was suddenly caught developing a highly lethal, seal-less A-rank jutsu out of thin air, he wouldn't even have a chance to explain himself. The village Anbu would capture him as a foreign spy before the day was out.
Standing in the center of his sparse living room, Sengoku filled a balloon with water, tied off the neck, and rested it heavily on his palm.
He recalled the core theory: inject chakra into the water inside, but do not let it disperse evenly. Instead, force it to spin chaotically in multiple intersecting directions, creating enough internal centrifugal force to tear the balloon apart from the inside.
The concept was simple; the execution was a nightmare.
During his initial attempts, his chakra either failed to penetrate the water effectively, leaving it stagnant, or he lost focus, allowing the rotational force to leak outward. The latter either launched the balloon off his hand like a projectile or caused premature, localized ruptures that sprayed water all over the room.
Failure followed failure.
Sengoku wiped the cold water from his face with a deadpan expression, grabbed a fresh water balloon, and started again. With every burst, he analyzed his mistakes: the entry angle of his chakra, the initial speed of the rotation, the balance of the internal currents, and the stability of the core.
He repeated the process tirelessly. Soon, the air in the small stone house grew humid, and puddles formed around his feet. The wet slap and pop of bursting balloons echoed for hours.
It wasn't until the twilight of the second day, when his reserve of balloons was nearly depleted, that a breakthrough occurred.
The water balloon resting in his palm suddenly began to churn violently. A low, muffled humming sound emanated from the water as invisible forces dragged and warped the rubber, causing erratic, bulging spikes to push outward against the skin of the balloon.
Pop!
With a sharp crack, the balloon detonated, sending a heavy splash of water in all directions.
Sengoku stared at his empty, dripping palm. He memorized the phantom sensation of perfectly guiding the chaotic, high-speed rotation right up to the point of structural failure. A faint gleam of satisfaction flashed in his eyes.
Step one was complete.
Without pausing to celebrate, he grabbed his remaining balloons and reinforced the muscle memory until the bag was empty. Only then did he reach for one of the thick rubber balls.
The difficulty instantly spiked. The dense rubber possessed a durability that vastly exceeded the fragile balloons. It demanded a significantly stronger, denser, and more stable rotational force to breach.
Sengoku channeled his chakra into the rubber ball.
It vibrated slightly, then went still. No matter how much chakra he pumped into it, he couldn't generate the violent internal rotation necessary to compromise the thick shell. It felt like trying to slice through cured leather with a blunt knife; the force simply couldn't gain purchase.
He realized he needed a higher volume of chakra output, coupled with far more intricate control. He couldn't let the kinetic energy scatter; he had to compress the rotation into a concentrated storm of continuous, localized friction.
Closing his eyes, Sengoku shut out the damp room entirely. He sank his entire consciousness into the sensation against his palm, micro-adjusting the speed, angle, and density of the swirling chakra.
Time slipped by in absolute silence.
Eventually, the heavy rubber ball began to tremble. A high-frequency, wasp-like buzz filled the air. Inside the sphere, an immense pressure was visibly struggling, desperately trying to tear its way out.
Fine beads of sweat broke out across Sengoku's forehead. Maintaining this extreme level of microscopic control placed a massive burden on both his mental stamina and his chakra network. Yet, his hand remained perfectly steady.
The buzzing grew louder, sharper.
Riiip!
The harsh sound of thick fabric tearing broke the tension.
Driven by the invisible, violently spinning chakra, a jagged fissure ripped open from the inside out across the surface of the tough rubber. It hadn't violently exploded into pieces, but the structural integrity was completely destroyed.
Sengoku slowly withdrew his chakra and exhaled a long, heavy breath.
Looking at the torn rubber ball in his hand, he knew the second step was halfway done. The rest was simply a matter of grinding through the process until he could obliterate the ball completely.
As for the third step—condensing, compressing, and stabilizing the rotating chakra sphere perfectly without any physical shell to contain it—that required a level of control he was currently far from achieving.
Moving methodically, Sengoku swept up the rubber scraps and mopped the floor. He ate a simple, cold ration, sat down to refine his depleted chakra, and picked up a fresh rubber ball.
The training continued.