The air in the classrooms had gained a tangible density, the quiet hum of study replaced by a high-frequency buzz of anticipation. The aftermath of the previous night's exchange with Riku had resonated through the student body like an unexpected seismic event. Kai didn't just feel watched; he felt measured. Every glance was a data point, every whisper a comment field in his personal threat matrix.
He found the scrutiny draining. Emotional friction, he noted, was a colossal waste of energy. To counteract it, he sought the one place where chaos yielded to order: the vast, dimly lit library stacks. He didn't seek escape, but acceleration.
He was hunched over a heavy textbook on classical mechanics, his mind tracing the elegant formulas governing the universe. He was hunting for a concept that could serve as the foundation for his Systematic Style, Mark II. The Rotational Algorithm was efficient, but it was just a specialized tool. He needed a general theorem—a fundamental truth he could leverage.
He paused on a section about Conservation of Momentum. The principle was simple: total momentum remains constant in a closed system. But a fight wasn't a closed system; it was two systems violently colliding. The key, then, wasn't to preserve his own momentum, but to force the exchange of the opponent's momentum into directions that destabilized them.
Kai traced the formula for impulse, J=F⋅Δt, where J is impulse, F is average force, and Δt is the contact time. The Rotational Algorithm had maximized F instantly. The Mark II, he realized, needed to maximize the effective Δt at the point of contact to translate kinetic energy into a rotational impulse.
Maximize impulse, minimize exposure. That was the new directive.
Just as the pieces of the theoretical puzzle clicked into place, the light above him dimmed. A heavy shadow fell over the page, eclipsing the elegance of the textbook.
"Looking for the cheat codes, transfer student?"
Kai closed the book slowly, marking the page with a clean slip of paper. He looked up at Juro. A 2nd-year renowned for his immovable physique, Juro was nicknamed "The Anchor." He wasn't one of the sleek, fast-moving lieutenants Kai had faced yesterday, but a tower of brute strength, his martial art based purely on generating overwhelming mass and force.
Juro stood outside Riku's immediate circle, but his motivation was clear: use the rising tension to secure his own reputation. Kai was the perfect stepping stone.
"This corner of the library is reserved for theory," Kai replied calmly, rising to his full height. "If you're looking for application, the dojo is two floors down."
Juro's expression hardened. "The application starts now. You're a calculation waiting to be nullified, transfer student. I'll prove that brute force still breaks elegant formulas."
Juro didn't wait for an answer. He turned sharply and walked toward the rarely used storage room adjacent to the dojo—a narrow, cluttered space that offered no room for complicated footwork, forcing close-quarters, high-risk engagement. Kai followed, his mind instantly shifting from passive study to active threat assessment.
The Unexpected Challenger
The storage room smelled of disinfectant and old leather. The walls, lined with discarded equipment and spare mats, narrowed the fighting space to a dangerous corridor. Juro spun to face him, his stance solid as a foundation.
Kai's systems went live. Threat Level: High. Juro's immense mass translated to high inertia. Evading Juro's momentum would require excessive energy; neutralizing it would require a fundamental system overwrite.
Juro initiated the attack with a powerful, straightforward right cross. It was a simple strike, but the sheer force behind it was staggering. Kai's internal sensors estimated the power output at 150 units—more than enough to shatter a standard block.
Kai didn't block. He executed a Micro-Shift Evasion, a controlled back-step of precisely 3 cm while rotating his upper body 15 degrees away from the impact vector. The punch sliced through the air, the wind of the blow barely missing his ear.
Juro's Range and Power: Confirmed. Strike Velocity: Medium. Recovery Time: Slow (due to mass transfer).
Kai saw his opportunity in the brief pause as Juro attempted to recall his massive arm. He utilized a lightning-fast feint, testing Juro's reaction time. Juro's response was sluggish, confirming that his size, while an asset in power, was a devastating liability in speed.
Juro roared, frustrated by the evasion. He switched to a sustained, power-focused assault, driving forward with heavy, piston-like blows. Kai maintained his defensive shell, absorbing minor impacts on heavily muscled areas while always ensuring his center of mass remained stable.
He calculated Juro's movement pattern: highly aggressive, relying entirely on maximizing forward momentum. The flaw was consistent: Juro's stability was nonexistent during the peak of his heavy swings, leaving his core vulnerable to sudden lateral force.
Targeting the flaw: The Rotational Algorithm - Mark I is the most efficient counter-attack in the current toolbox.
Kai waited for Juro's next over-extended hook, allowing the blow to draw Juro's entire 100 kg mass into a vulnerable rotation.
Applying the Mark I
In that microscopic window of maximum vulnerability, Kai launched his counter.
He executed the 2 cm slide—a subtle friction-leveraging shift of his lead foot. This immediately initiated the spin, maximizing his rotational velocity with minimal internal effort. He was no longer pushing himself; he was leveraging the floor.
As his torso whipped around, he engaged the controlled energy burst—a sharp, synchronized exhalation that locked his core and channeled all accumulated momentum into his extended leg.
From Juro's perspective, Kai simply vanished from his blind spot and reappeared as a blur of motion. The Rotational Algorithm - Mark I was executed perfectly.
The kick connected squarely with Juro's lower abdomen, hitting him with the optimized force of 135 units. The impact was brutal, designed to violently disrupt internal equilibrium.
But Juro, the Anchor, merely stumbled.
He didn't drop. He didn't collapse. He took three heavy, staggering steps back, a grimace of pain contorting his face, but his defensive inertia held. He crashed against a stack of rolled mats, disrupting the room, but he remained on his feet, ready to continue.
Kai's mind flashed red: SYSTEM FAILURE. Expected Result (Disabling Stun) = Actual Result (Stumble).
The flaw was critical. The Rotational Algorithm was highly efficient, but it was designed against average 70 kg opponents whose internal structure would be violently compromised by that kinetic transfer. Against Juro's massive inertia, the force was absorbed and dispersed through sheer density. The Mark I lacked penetration.
Kai realized the kick had been too much of a snap—a high force, short duration strike. To defeat Juro's inertia, he needed to increase the duration of contact time (Δt) to maximize the impulse (J), even if the peak force (F) remained the same.
Juro, seeing Kai frozen for a fraction of a second in analytical shock, seized the opportunity. He lunged forward, not with a precise strike, but with a full-body shoulder charge—a desperate move designed to flatten Kai through pure, overwhelming mass.
Kai had less than half a second to respond.
Flaw and Adaptation
New Variable: Inertia Negation. Immediate solution required.
Kai's mind discarded evasion; the narrow space made an escape too risky. He had to meet the momentum, not dodge it. He needed a Mark II.
He couldn't change his stance or his rotational velocity in time, but he could change the geometry of the impact.
As Juro's shoulder charge closed the distance, Kai didn't initiate another kick. Instead, he executed a rapid, small lateral hop, moving his center of mass just 10 cm to the side of Juro's vector. He then utilized his entire right arm, not for a block, but to receive the momentum through his forearm, using his elbow as a carefully positioned lever point.
This was the Shear Force Adaptation (Mark II).
Instead of fighting the 100 kg forward momentum, Kai converted it. The moment Juro's mass impacted his stationary elbow, Kai didn't resist. He guided Juro's momentum in a rapid, downward arc, simultaneously using his left foot to push against Juro's lead leg.
The action was swift, cold, and devastatingly logical. By turning the linear forward thrust into a rotational downward vector, Kai leveraged Juro's 100 kg mass against itself. The force that Juro intended to apply was now applied to his own center of gravity, violently throwing him off balance.
Juro's eyes widened in confusion a split second before his world inverted. He was no longer charging; he was falling—a massive, uncontrolled 100 kg stone. He impacted the concrete floor with a sickening thud, the wind knocked out of him. He lay still, his massive frame helpless.
Kai stood over him, his breathing steady at 80 BPM. His elbow throbbed, a manageable 2/10 on the pain scale.
The test was complete. Kai glanced at the fitness tracker on his wrist, which he used as a rudimentary sensor log.
Result: Win. New System Flaw Identified: Inertia Negation. Solution: Shear Force Adaptation (Mark II) successful. Note: Optimize contact geometry.
He stepped around Juro's stunned body and walked out of the storage room. The test had not been to defeat Juro; it had been to discover the limitations of his own logic.
Riku was a system unlike any other. Kai had just proven that his own system could evolve instantly under stress. The rivalry was no longer a question of strength, but a complex, high-stakes game of systematic optimization. And Kai was ready for the next round of code.