Aizen had seen biological-type Zanpakuto before, but this was indeed the first time he had heard of such a method.
Generally speaking, the Shikai of a Soul Reaper's Zanpakuto primarily focused on combat abilities. Even if a small number were meant for support, they wouldn't exist on such a microscopic level...
To think that his former experimental subject had been eliminated in such a manner...
'It really goes round and round, only to circle back to you... Number Seventy-Eight...' Aizen muttered inwardly.
"Reishi insects?" Toshiro Hitsugaya, who was listening to the story from the side, also revealed a curious expression.
Rangiku Matsumoto felt a chill run down her spine, as she wasn't very fond of bugs. "I never expected Miss Kocho's Shikai to have this kind of ability..."
"Yeah," Kaien said, bitterly recalling the strange sensation inside his body that night. "Those insects can burrow in along the Spirit Ribbon, acting like scavengers to accurately identify and devour the parasitic remnants of a Hollow."
Aizen took a sip of the tea in his hand and smiled. "Miss Kocho is indeed a rare genius. To be able to control Reishi insects with such precision, I'm afraid even the Department of Research and Development would be interested."
"Captain Aizen must be joking. I don't think Miss Kocho would like being stared at by those mad scientists," Kaien said, waving his hand with a laugh.
Aizen smiled faintly. "I misspoke..."
Next, Aizen, Kaien Shiba, and Toshiro Hitsugaya discussed some topics regarding squad management, specifically mentioning cross-departmental cooperation, and briefly drafted a few proposals.
After leaving the Tenth Division barracks, Aizen walked alone on a quiet path.
The gentle smile on his face had not disappeared, but the eyes hidden behind his glasses gave off a chilling sensation.
Metastacia was the name of the experimental subject he had meticulously cultivated, a pioneer creation meant to test Hollowfication.
According to his calculations, that kind of parasitism should have been irreversible...
Back then, he had been puzzled. For the Fourth Division's medical level to actually cure this mutation... This had once made him doubt the results of his experiment.
"Time truly is a complex subject, Number Seventy-Eight," he muttered to himself. "The little butterfly you brought back, the wings she flaps are forming a storm in my world..."
"So today... the two girls Miss Kocho sent to the Shin'o Academy, are they also guests from another world like her...?"
Aizen took out a neatly folded letter from his chest pocket.
It was the annual schedule of this year's courses sent by the Shin'o Academy to all instructors.
Aizen looked at the few lectures assigned to him, his eyes flickering.
"I happen to have nothing going on. I should hold a few more open lectures."
The summer passed by in a flash.
Although the original plan was to train for about a month, in reality, to strive for perfection, Asuka had been sweating it out for a full three months.
The underground training ground of the Urahara Shop.
The air here was taking on an almost viscous texture due to the recent continuous, high-intensity Spiritual Pressure battles.
Over these ninety days, Asuka had experienced more than just physical torment.
From initially being toyed with by Yoruichi like a teased kitten, to gradually being able to catch a glimpse of that black afterimage, and finally to today...
His transformation was astonishing.
This change was not an explosive increase in his total Spiritual Pressure, but rather it becoming more condensed.
At this moment, Asuka stood quietly in the center of the sandy terrain.
He was shirtless, every inch of his muscles like tempered steel that had been rigorously forged and refined, his lines smooth and full of explosive power.
In his eyes, the anxiety and gloom born from losing his power had completely vanished.
A steadiness like the deep waters of an ancient pool was suppressing his sharp edge.
He simply stood there, his breathing imperceptible, the Spiritual Pressure around him tightly contracted within three inches of his skin.
He was waiting.
Swoosh--!!
A lightning-fast black shadow struck, so quick it created a visual disconnect.
Almost at the exact same moment, Yoruichi appeared to Asuka's back left.
A slender palm, yet containing the force of a thunderbolt, struck down abruptly, aiming straight for the vital acupoint on the back of Asuka's neck!
According to the script from three months ago, Asuka should have been directly flipped over by this strike, then sent rolling across the ground a few times.
But now, things had changed.
Asuka's ankle subtly twisted at a minute angle. In the split second before the wind of the palm touched his skin, his entire body slid three inches to the side in a manner that defied inertia.
"Hmm?" Yoruichi let out a soft sound of surprise, but her offensive did not fade.
Her right hand smoothly shifted from a palm into a hook, grabbing toward Asuka's shoulder once more.
"Tsurigaki," Asuka said flatly.
He dropped his shoulders and sank his elbows, his left hand shooting out like lightning to accurately block the inside of Yoruichi's wrist.
Using this as the main axis of attack, he not only parried the claw strike but also took advantage of the momentum to throw a punch at Yoruichi, whose center was left wide open!
"Good punch!" Yoruichi laughed loudly.
This move was a Hakuda technique of the Onmitsukido, and now Asuka had already thoroughly mastered it.
But the Flash Master was no ordinary opponent either.
She quickly adjusted her center of gravity, sweeping her long leg up to deliver a heavy kick toward Asuka!
Bang!!
Their fist and leg clashed violently in midair, unexpectedly stirring up a visible ripple of Spiritual Pressure!
At the edge of the training ground, a few figures were watching the confrontation ahead.
Tessai Tsukabishi maintained his usual stern demeanor, adjusting the glasses on the bridge of his nose, his massive body standing tall like an iron tower.
Beside him, Isshin Kurosaki was squatting frivolously on a rock, holding a blade of grass he had gotten from who knows where in his mouth, but his gaze never left Asuka for a moment.
"Mr. Tessai, did you feel it?" Isshin suddenly spoke, his voice uncharacteristically deep. "That kid's 'density'."
"Yes, Shi... Mr. Kurosaki," Tessai gave a slight nod, his voice resonant. "Three months ago, although his Reishi structure was stable, it was like a piece of unforged pig iron. But now... this iron is almost ready to be quenched."
Asuka was using the combat pressure Yoruichi brought him to continuously compress the density of the Spiritual Pressure within his body.
Even though he was also at Fourth-class Spiritual Power, his fourth-class far exceeded that of ordinary people.
Isshin narrowed his eyes. As a former Soul Reaper Captain, his judgment was incredibly sharp. "He is turning his own body into a Zanpakuto... With skills like this, he could even exchange a few blows with Captain Soi Fon..."
And from beginning to end, Kisuke Urahara had not said a single word.
'What do we do about this... We really won't be able to control him anymore...' he thought to himself.
In the center of the battlefield, the two were fiercely exchanging blows within a hair's breadth of each other.
Yoruichi's speed grew faster and faster, her afterimages almost overlapping to form a black storm circle.
Meanwhile, Asuka, situated in the center of the storm, was like a reef by the sea—no matter how the wind and waves battered him, he remained entirely unmoving.
Asuka's perception was pushed to its absolute limit.
He sensed the tremors of Yoruichi's muscles and the flowing trajectory of Reishi in the air.
At first, he had tried this, but because the gap in strength between him and Yoruichi was slightly too large, even with his perception maxed out, he couldn't capture Yoruichi's movements.
But this long-lost sense of clarity was becoming clearer and clearer as his Spiritual Pressure density increased.
"Not enough, I need to be even faster..."
Asuka had no distracting thoughts in his mind, only an ultimate thirst for battle.
Suddenly, Asuka caught a momentary opening.
When Yoruichi performed continuous high-speed movements, in order to maintain her body's balance, the moment her left foot landed would have a split-second more Spiritual Pressure stagnation than her right foot.
This was the opportunity!
Asuka's feet exerted a sudden burst of force, instantly reducing the rubble beneath his feet to powder.
"Ranshiki!"
He did not choose to dodge backward from Yoruichi's incoming barrage of kicks.
Relying on the sharp reflexes brought by his transparent perception, his entire body acted like a drill, forcefully carving into the wind of Yoruichi's kicks.
His speed erupted to the extreme in this instant, even producing a thunderous sound of tearing through the air.
Yoruichi's pupils suddenly contracted.
In her field of vision, Asuka's fist had already transformed into five sharp streams of energy, piercing straight toward her chest.
This was a genuine threat.
In that split second, Yoruichi's bodily instincts bypassed her brain's commands.
Crackle—!!
A trace of golden light, as violent as thunder, flickered faintly on Yoruichi's shoulders.
That was the precursor to the activation of Shunko, her Spiritual Pressure instantly materializing into a fierce wind that enveloped her entire body.
But in the instant the golden light was about to fully erupt, Yoruichi forcefully suppressed the impulse.
In a flash of lightning.
Yoruichi tapped her tiptoe against the empty air, forcibly twisting her center of gravity, and her entire body turned into an arc as she slid back over twenty meters away.
The dust settled.
Yoruichi stood in the distance, her chest heaving slightly.
She looked down at the training uniform on her right arm; a shallow slit had been cut into it at some unknown point.
That was the mark left behind by the wind of Asuka's punch just now.
'To think I was actually pushed to the point of a primal reaction, subconsciously wanting to use my full strength against this brat?' Yoruichi thought, feeling a sense of awe.
In the distance, Asuka still maintained his punching stance.
"Extra meal... three servings of Wagyu beef," he said.
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