The academy bell rang, signaling the start of the morning session. Sengoku took his usual seat in the back row by the window, his fingers tapping rhythmically against the wooden desk. His mind was entirely focused on analyzing the physical changes he had experienced during his early morning tests.
Sunada Shun strode into the classroom, the deep scar across his face catching the harsh morning light. He hung a detailed diagram of the human meridian system on the blackboard and tapped the pressure points located at the soles of the feet.
Today's lecture was the foundational theory of the Body Flicker Technique—Shunshin.
"When erupting chakra from the soles of your feet, frequency is more important than volume," Sunada explained, his voice as dry and steady as ever. "Three rapid, successive bursts conserve more chakra and generate significantly greater propulsion than a single, prolonged blast."
Sengoku listened with absolute focus. Thanks to his enhanced intellect, the mechanical logic of the technique instantly clicked into place.
During the afternoon practical class in the training ground, Sunada demonstrated the technique. While the other students watched the blur of the instructor's movement, Sengoku stared intently at Sunada's feet, carefully observing the precise, three-pulse chakra fluctuation with every step.
"Group up. Free sparring," Sunada announced.
Araki Ryo immediately walked over, his eyes scrutinizing Sengoku. "Let's go. Again." He dropped into a standard taijutsu stance, planting his feet firmly in the sand. His demeanor was noticeably more aggressive than usual.
The first clash happened in a flash. Araki launched a probing straight punch aimed at Sengoku's ribs. Sengoku casually raised his arm to block.
The expected heavy impact never came. Sengoku's arm caught the strike like an iron bar, absorbing the kinetic force flawlessly without even a tremor.
Araki's brow furrowed. He immediately shifted his weight and swept his left leg low, aiming to take out Sengoku's footing. Sengoku simply took a half-step back and drove his own right leg forward to meet the sweep.
Thud.
Bone met bone. Araki stumbled backward, his eyes widening in shock. "Your strength..." he started, quickly cutting himself off as he reset his stance.
Sengoku said nothing. He was treating the spar as a live-fire calibration test, actively adjusting to the output of his newly enhanced muscles.
Changing tactics, Araki began to circle, his footwork erratic as he unleashed a flurry of strikes from multiple angles.
"Too slow!" Araki yelled, suddenly accelerating. He chopped a vicious knife-hand toward the side of Sengoku's neck.
Sengoku tilted his head, letting the strike breeze past. His body moved faster than he had even anticipated. Simultaneously, his left hand deflected Araki's arm while his right hand locked onto the boy's wrist. Pivoting on his heel, Sengoku executed a flawless shoulder throw, slamming Araki hard into the sand.
Araki grunted, quickly rolling back to his feet. He glanced away, clearly embarrassed, and cleared his throat loudly. "I slipped. Guess I need to stop holding back."
A visible aura of chakra flared around Araki as he launched himself forward again. His attacks became a frantic storm of blows.
As Araki spun into a high, sweeping kick, Sengoku noticed the boy's center of gravity tilt a fraction too far forward. In the past, Sengoku could see these flaws but lacked the physical speed and strength to exploit them, forcing him to remain on the defensive.
Not anymore.
Instead of stepping back, Sengoku darted inside the guard. He snapped a precise kick directly into the side of Araki's supporting knee. The moment Araki lost his balance and pitched forward, Sengoku slipped smoothly behind him, resting the cold, blunt edge of a training kunai against his throat.
"Halt." Sunada materialized at the edge of the ring, his expression completely blank as he jotted something down on his clipboard. "Next pair."
Araki stepped back, panting heavily as he dropped his stance. He stared at Sengoku for a long moment. "You're completely different today."
Sengoku quietly holstered his kunai. The new strength point hadn't just given him more hitting power; it had granted him total control over the rhythm of the fight.
When the dismissal bell rang, Araki rubbed his bruised arm and leaned in close. "Seriously, what's going on with you? Did you figure out some secret training method?"
Sengoku paused his packing and looked the boy dead in the eye. "I attribute it entirely to my peerless talent and relentless daily training. Five hundred pushups, five hundred squats, five hundred shuriken throws, and five hundred chakra control exercises. It is simply the basics."
Araki's eye twitched. "I could maybe buy the physical stuff, but five hundred chakra control exercises?! Do you think I'm an idiot?"
"Believe what you want." Sengoku slung his tool pouch over his shoulder and turned toward his usual isolated corner of the grounds. "I just spend the time you use gossiping on actual training."
Araki opened his mouth to argue, thought better of it, and walked away muttering under his breath.
Once the grounds were completely empty, Sengoku stood alone in the fading light. The sand still radiated the day's heat. He didn't immediately attempt the explosive Shunshin technique; instead, he began his usual warm-up.
Spreading his fingers, a pale-blue chakra thread shot out, perfectly latching onto a kunai buried in a target dozens of meters away. With a gentle flick of his wrist, the kunai sliced through the air and snapped back into his palm. The motion was as natural as breathing.
After completing his thread and throwing exercises, he ate a quick ration and moved to the rock wall. Channeling a steady flow of chakra to his soles, he walked vertically up the five-meter sandstone face and hung upside down from an overhang, completely stable.
As the sky bruised into twilight, Sengoku finally turned his attention to the Shunshin.
He recalled Sunada's exact phrasing: 'When the foot meets the ground, do not release the chakra all at once. Break it into three short pulses.'
Attempt one: Sengoku pushed too much chakra into his foot. The sand beneath him violently exploded into a crater, and the sheer recoil nearly launched him backward on his spine.
Attempt two: His timing was uneven. He stumbled forward a few chaotic steps and lost his balance entirely.
Attempt three: His output was too weak, resulting in a slightly faster-than-average running stride.
He didn't feel a shred of frustration. He simply broke the mechanic down further. He started by isolating his right foot, stepping forward and trying to trigger just two distinct pulses upon contact with the sand.
It struck him that this internal mechanism was remarkably similar to manipulating a chakra thread. Both required absolute rhythm control and precise micro-adjustments in output.
On his tenth attempt, he broke through. The moment his right foot hit the sand, two distinct pulses fired. His body shot forward a meter and a half—nearly double his normal stride length.
"Still not enough," he murmured. Sunada had used three pulses and covered a massive distance effortlessly.
On his twentieth attempt, Sengoku adjusted the distribution of the energy. The first pulse would be soft, acting as a primer to initiate movement. The second would be violent, providing the explosive main thrust. The third would be a short, sharp burst to stabilize his posture upon landing.
He stepped forward.
Boom.
The sand sprayed backward, and Sengoku launched forward like a fired arrow, crossing three meters in the blink of an eye. He wobbled heavily upon landing, but the propulsion was undeniable.
His eyes lit up in the gathering dark. He threw himself into the practice, tweaking the intensity and rhythm of the pulses with every failure. Sometimes he pushed too hard, leaving his feet numb; other times, he mistimed the third pulse and ate sand.
By his thirty-fifth attempt, he could reliably trigger the three-pulse sequence. Every step propelled him three to four meters instantaneously, leaving faint afterimages in the fading light.
However, the drawbacks were glaring. The technique burned through his chakra reserves at a terrifying rate, and he could only travel in a perfectly straight line. Any attempt to turn mid-dash completely shattered his balance.
By the time the sun fully disappeared below the horizon, Sengoku's chakra was tapped out. His leg muscles felt like lead. The training ground was covered in his tracks—a physical record of progress that started as chaotic, stumbling craters and smoothed out into long, precise lines.
He packed his gear and walked home under the starry sky.
Pushing open the heavy stone door, he was greeted by the familiar, dusty smell of his room. He lit the oil lamp and unrolled a new scroll he had acquired, titled Chakra Thread Manipulation.
The yellow light flickered over the parchment as he found the chapter on "Chakra Pulse Micro-control." His fingers traced the desk, absentmindedly mimicking the three-beat rhythm of his new movement technique.
The scroll's theories were far more intricate than Sunada's academy lecture, but the core philosophy aligned perfectly. Puppetry was initially engineered based on the human meridian system. Therefore, the foundational principle of pulsing chakra to achieve hyper-precise mechanical control applied equally to a wooden joint and a human leg.
Sengoku ran through his thread exercises one last time to drain the final dregs of his energy, then blew out the lamp.
Lying in the dark, his mind remained active. He replayed the kinetic feedback of the day—the smooth deflection of Araki's punch, the successful three-pulse dashes, and the jarring failures—drifting into sleep while actively cementing the new muscle memory.