The taste of victory over Sasuke's fireball was ash in Renji's mouth now. Not because it didn't work – it had worked beautifully – but because of the agonizing slowness. Twenty seconds. An eternity in combat. A liability. The memory of the searing heat grazing his skin, the desperate dives, the jeers before the final success… it fueled a new kind of obsession.
He needed speed. Raw, brutal processing speed for his Pulse Sense. Three seconds. That was the impossible benchmark he'd set. Analyze, isolate resonance, strike. Three seconds.
The training grounds became his crucible. While others practiced flashy clones or elemental manipulation under Iruka's watchful eye, Renji stood apart. He'd face a simple wooden target dummy, or a hanging leaf, or later, a reluctantly volunteered Naruto throwing predictable kunai.
He'd close his eyes, blocking out the shouts, the thuds, the rustling leaves. Inside, a storm raged. Chakra, that ephemeral energy he'd learned to quantify and manipulate like voltage or frequency, churned within his coils. He'd push it out, not in a blast, but in a focused, rapidly oscillating cone – his Pulse Sense scan. The feedback was a cacophony: the dense, fibrous resonance of the wood grain; the fluttery, chaotic signature of the leaf; the sharp, metallic ping of the kunai spinning through the air.
The task? Filter the noise. Instantly. Identify the dominant harmonic structure. Hold that frequency in his mind like a tuning fork while simultaneously shaping a matching counter-pulse. It was mental gymnastics on a razor's edge. One moment of lost concentration, and the Pulse Sense would fracture, the feedback dissolving into meaningless static.
"Focus, Renji!" Iruka would call out occasionally, his voice cutting through Renji's internal struggle. "Don't force the chakra flow! Let it resonate naturally!" Renji would grit his teeth. Natural? There was nothing natural about dissecting reality with math while standing in a field. But he'd nod curtly, adjust, try again. Sweat plastered his blond hair to his forehead, stinging his blue eyes.
Progress was glacial. Days bled into weeks. He could analyze the static dummy reliably in ten seconds. The leaf, with its erratic movement, took fifteen. Naruto's kunai? Twenty-five, sometimes more, especially if Naruto added an unpredictable wobble with a gleeful "Believe it!" Renji's knuckles grew white around the kunai he practiced his counter-pulses with. Frustration was a constant companion, a low thrum beneath his focus.
He barely noticed the subtle shifts in the village atmosphere at first. The whispers seemed louder, harsher. Eyes lingered on certain uniforms. An unnatural tension hung in the air, thicker than the summer humidity. Then, one crisp autumn morning, it shattered.
The news hit the academy like a physical blow. Renji, arriving for another grueling session, found the training ground silent. Unnervingly silent. Naruto wasn't bouncing. Kiba wasn't boasting. Sakura and Ino stood close together, pale-faced, eyes red-rimmed. Choji stared at the ground, his snack forgotten. Shikamaru looked more tired than Renji had ever seen him.
Iruka's face was carved from stone. His voice, usually firm but kind, was rough. "Class is suspended today. Go home. Be with your families."
"What happened, Iruka-sensei?" Sakura whispered, her voice trembling.
Iruka closed his eyes for a moment. "There was… an attack. Last night. On the Uchiha compound." He didn't need to say more. The collective intake of breath, the dawning horror, told Renji everything. The Uchiha. Wiped out. He remembered the history – the tension, the distrust. Itachi. Sasuke.
Sasuke.
Renji scanned the group. The brooding Uchiha was conspicuously absent. A cold knot formed in Renji's stomach. The prodigy he'd measured himself against… his entire world just evaporated.
The following days were a blur of hushed voices and drawn curtains. The village mourned, or pretended to, or simply feared. Renji tried to train, but the focus was gone. The resonance frequencies seemed trivial, meaningless noise compared to the echoing silence from the Uchiha district. He saw Sasuke once, briefly, being escorted by stern-looking ANBU. The boy's face was pale, blank, eyes hollow pits staring straight ahead, unseeing. The vibrant, arrogant spark of challenge Renji had seen when testing the fireball jutsu was utterly extinguished, replaced by a chilling emptiness. The change was jarring, a fundamental shift in the world's axis.
Life, or a semblance of it, slowly seeped back into the academy. Sasuke returned, but he wasn't the same. He moved like a ghost, spoke only when absolutely necessary in clipped monosyllables. His eyes, when they met anyone's, held a frozen fury so deep it felt like looking into the void.
Sakura approached him constantly, her voice soft, laden with concern. "Sasuke-kun? Would you like some water?" "Sasuke-kun, did you understand that last technique?" "Sasuke-kun…" Her efforts were met with stone walls, icy dismissals that only seemed to fuel her determination. Ino, ever the rival, adopted a different tactic. Brash, demanding his attention. "Oi, Sasuke! You can't just mope forever! Spar with me!" "Stop ignoring everyone, Uchiha!" Her attempts were met with a withering glare or complete indifference, a rejection that stung visibly despite her proud posture, though Renji caught the flicker of genuine worry beneath her bluster when she thought no one was looking. Her gaze sometimes, almost unconsciously, shifted towards Renji during these moments, a split second of shared, unspoken unease before snapping back to Sasuke or Sakura.
Naruto, predictably, was the most direct. "Sasuke! You gotta fight me! You're acting weird!" He'd charge, only to be effortlessly swatted aside or avoided with contemptuous ease. "Shut up, dead last," Sasuke would snarl, the words dripping with a venom that silenced even Naruto for a moment. The raw pain in Naruto's eyes whenever this happened was a stark contrast to his usual boisterousness. He'd scramble up, dust himself off, and glare, a wounded stubbornness replacing his usual grin. "I'll make you fight me for real one day, teme! Believe it!"
Renji observed it all with a detached, analytical coldness that surprised even himself. He saw the trauma in Sasuke's micro-expressions, the tightening around the eyes, the minute tremor in his hands before he clenched them. He saw Sakura's desperate need to fix something unfixable, Ino's frustration masking concern, Naruto's incomprehension translating into clumsy aggression. He understood the dynamics, the psychological pressures. But understanding didn't translate to empathy. It was data. Tragic, disruptive data.
He returned to his training with renewed, almost desperate, intensity. The world outside was messy, violent, illogical. But the resonance frequencies? They obeyed laws. Predictable, immutable laws. Finding the harmonic weakness in a water whip Kurenai-sensei demonstrated took him eighteen seconds. Too slow. A basic earth wall erected by Iruka: fifteen seconds. Progress, but agonizingly insufficient.
He pushed harder. He tried splitting his chakra focus – maintaining the Pulse Sense scan while simultaneously initiating the rudimentary shaping for the counter-frequency. It felt like trying to write two different essays simultaneously while reciting poetry backwards. His chakra control frayed. Headaches became constant companions, throbbing behind his eyes. He'd stumble during spars, his reactions dulled by mental exhaustion.
"Pushing too hard, Renji," Iruka said quietly one afternoon, watching him fail to counter a simple Academy-level genjutsu because his Pulse Sense scan faltered. "Strength isn't just speed. It's endurance. Stability."
Renji just nodded, wiping sweat from his upper lip. Stability was irrelevant if you were dead before you could analyze the killing blow. He needed speed. He saw Sasuke watching him from the edge of the field, that hollow gaze devoid of its former competitive spark. It wasn't a challenge anymore; it was a reminder of consequences. Of what happened when you weren't fast enough, strong enough, prepared enough. The Uchiha massacre wasn't just Sasuke's tragedy; it was a brutal lesson in the cost of vulnerability.
The summer heat returned, thick and oppressive. Cicadas screamed in the trees bordering Training Ground 3. Renji stood alone, facing a practice log. He closed his eyes. Three seconds. He initiated the Pulse Sense. The familiar torrent of data flooded in – the grain, the knots, the moisture content. But instead of trying to process it all at once, he forced a mental division. Priority: Structural integrity. Secondary: Density variations. He ignored the moisture, the surface texture. He narrowed the scan's frequency band, sacrificing breadth for processing speed on the critical data.
The log's resonant frequency snapped into focus. Eleven seconds.
Still too slow. He growled low in his throat, a sound of pure frustration. He tried again. And again. Ten seconds. Nine. Then back to twelve. Inconsistent. Unreliable. His head pounded.
He recalled the fireball. The deep, anchoring hum. How he'd finally locked onto it. How his counter-pulse had been pure, single-frequency, once he knew the target. The analysis was the bottleneck. The emission could be near-instantaneous if he knew what to emit.
A spark. What if… instead of one broad scan, he fired multiple micro-pulses? Each tuned to a specific, narrow band of frequencies? Like a shotgun blast of queries instead of a single, searching beam? He could cover the spectrum faster, parallelizing the search. The chakra control required would be insane – maintaining multiple distinct frequencies simultaneously. But theoretically… it could slash the analysis time.
He opened his eyes, ignoring the throbbing in his temples. A wild, desperate hope flickered. It was madness. It would demand control he didn't yet possess. But it was a path. A way forward through the impossible bottleneck. Years of work stretched ahead, a daunting mountain range of failure and refinement. But the summit – those three seconds – suddenly felt less like a mirage and more like a destination.
He took a deep breath, ignoring the sweat dripping into his eyes, the distant shouts of his classmates, the oppressive weight of the recent past. He closed his eyes again. The cicadas screamed. Inside his mind, he began the agonizing process of splitting his chakra focus, forcing it to vibrate not as one, but as two distinct, dissonant threads. The headache flared white-hot. But he held them. Barely. Two pulses. Two questions sent into the substance of the log. The first step on a much steeper path. He gritted his teeth and pushed.