On Rifu Mountain, Kurotsuki Renya placed two shuttle-shaped metal projectiles in front of him, each weighing about four kilograms.
Renya extended his left hand, and one of the projectiles rose into the air, suspended before his palm. With a surge of reiryoku coursing through his arm, the projectile began to spin rapidly, gathering a magnetic field of condensed spirit particles.
Whoosh—
When the rotation reached its limit, Renya shifted the polarity of the magnetic field. The projectile gained a sudden burst of acceleration and launched forward at frightening speed.
Boom!
A thunderous crack echoed across the mountain as smoke and dust erupted from a distant rock wall.
Renya approached the impact site. A massive crater scarred the rock face, the metal shell buried deep inside. The entry hole was nearly half a meter wide but tapered as it tunneled more than ten meters into the mountain.
The boy's eyes narrowed with satisfaction. If this had been aimed at a target… even hierro could be pierced.
Though the rock wall lacked the density of an Arrancar's skin, the principle was clear—speed and concentrated impact made defense nearly impossible. His tests showed his shots could reach nearly six times the speed of sound. Against a body hardened with hierro-level durability, the result would still be catastrophic.
Even more encouraging, his reiatsu consumption remained minimal. Most of his energy went into forming and stabilizing the magnetic field for acceleration, not sustaining the projectile itself.
Still, the prototype was lacking. The weight of his current shells was only 1.6 kg, much lighter than what the human world's science once experimented with. Renya knew from Soul Society's archives that some advanced human weapons had achieved seven times the speed of sound with ten-kilogram shells. My version is too small-scale…
If he could somehow construct a reishi-based turret—an external focusing device that directly converted reiryoku into a stabilized magnetic field—the results could be devastating.
If all of my spiritual power were converted purely into electromagnetic force through a proper conduit… speeds of over six kilometers per second might be possible. The destructive force could annihilate even an enemy like Aizen—before he fused with the Hōgyoku.
But Renya also knew the limitations. The craftsmanship required was beyond what Seireitei's forges could currently achieve. The necessary materials and engineering precision simply didn't exist yet in the Soul Society.
So, until then, this remains a theoretical weapon. In real combat, the acceleration time creates an opening. An opponent of Captain-level speed could evade before the strike landed.
Renya considered lighter projectiles for faster release, though he knew this would sacrifice power. For now, it was better suited to surprise tactics or containment strategies.
He made a note to design specialized shells—ones carved with grooves and sharpened edges—that could serve as close-combat throwing weapons while doubling as electromagnetic ammunition in battle.
With the test concluded, Renya turned his attention to another technique. He raised his left hand, reiatsu sparking as arcs of electricity converged, condensing into the form of a small bird.
With a flick of his palm, the lightning construct shot forward.
Boom!
The bird detonated against a boulder, scattering debris.
Renya's brow furrowed. Unsatisfied, he focused harder. Blue sparks danced around him until a dozen small thunderbirds took shape, circling him before flying out in rapid succession.
Boom! Boom! Boom!
The explosions tore fresh craters into the rock face, until the mountain wall collapsed into a jagged cave.
"Chidori," Renya muttered. The sound of countless birds chirping filled the air, but unlike the ninjutsu of old legends, his version carried explosive force.
Yet his progress was limited. Even if he poured all his spiritual energy into it, he could only manifest a hundred of the birds at most. Still, it's a start…
A familiar voice called from behind, interrupting his thoughts.
"You brat—messing up the mountain again."
Renya turned with a smile. "Senior Shiba."
Shiba Kaien approached, shaking his head as he inspected the smoking craters. "At this rate, Rifu Mountain's going to collapse. As punishment, you're going to help me with something."
Renya tilted his head curiously. "What task?"
Kaien smirked. "It's about Kuchiki Rukia…"
Renya's eyes sharpened. If it involved Rukia, he would help without hesitation. She was his classmate, his friend—and someone who often bore more than she showed.
Kaien explained that since Rukia had been admitted into the Thirteenth Division under Kuchiki Byakuya's sponsorship, she had faced whispers of favoritism and cold treatment from others. Byakuya's distant indifference had only worsened her isolation.
Kaien wanted Renya to look out for her, encourage her, and ease her burden where he could.
Renya agreed at once. Still, he knew that Rukia's true growth could only come from within. All he could do was support her from the sidelines.
In the days that followed, Renya spent more time with Kaien, sparring and exchanging ideas. Their matches often ended in stalemates—though Renya refrained from drawing his zanpakutō, relying instead on kidō and shunpo. He knew his techniques gave him an advantage, but he also recognized Kaien's natural talent.
Kaien's potential was undeniable. If given forty years, Renya believed he could certainly achieve Bankai.
But that knowledge weighed heavily. Renya remembered Kaien's fate—his wife, and later himself, would be consumed by Metastacia, an event that scarred Rukia for life.
I won't let that happen.
Renya began to consider preventative measures. The Onmitsukidō maintained surveillance squads with authority to track and report suspicious movements. If he could assign discreet monitoring to the Shiba family, he might detect Metastacia's emergence before it struck.
It would not be easy, but Renya resolved to act. With careful observation and timely intervention, he could change the outcome of Kaien's tragic future.
And he would.
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