Aizen turned and walked back to the lab table, beginning to organize today's data.
His movements were unhurried, the tip of his pen scratching across the paper with a faint rustling sound.
But his attention was not entirely focused on the notebook.
Behind him, Hasumi Ren's practice continued.
Spiritual pressure gathered in his palm, then dissipated.
Every attempt was smoother than the last; every release was more precise than the one before.
Aizen did not look back.
But his perception constantly enveloped that corner of the room.
Ren looked at the miniature Black Coffin in his hand. As the number of repeated casts increased, his proficiency gradually improved.
Aizen's pen paused slightly.
After the first success, Ren had failed a few times, forming unstable Kido that quickly dissipated in his hand.
But going from occasional failures to stably condensing a Black Coffin in his palm clearly showed that Ren's understanding of this Kido was deepening.
This rate of progress was truly somewhat astonishing.
Unconsciously, Aizen set down his pen.
He turned around and looked at Ren.
The young man stood in the corner of the cave, fine beads of sweat forming on his forehead, his breathing slightly ragged.
But his eyes were bright as he repeatedly attempted to condense the Kido in his hand.
Aizen made no sound.
He simply stood there quietly, his gaze resting on Ren.
Even for him, it had taken a considerable amount of time to train in a Kido of this level.
In the beginning, he had experienced countless failures before he could successfully cast it without an incantation.
And Ren? How long had he been practicing?
Aizen could tell that Ren's proficiency with Incantation Abandonment was not high; he was clearly just at the beginner's stage.
Yet, merely by listening to him break down the structure of Black Coffin once, Ren was able to successfully replicate it.
This... somewhat exceeded the bounds of Aizen's comprehension.
Aizen's gaze lingered on Ren for a long time.
Then, he suddenly spoke.
"Ren."
Hearing this, Ren stopped his movements and turned around.
"Lieutenant Aizen?"
Aizen did not speak immediately.
He just looked at Ren, his gaze profound, as if he were re-evaluating something.
After a moment, he spoke slowly.
"Incantation Abandonment. How long have you been practicing it?"
Ren looked at Aizen, wondering why he was suddenly interested in this.
"Not very long. After studying the theoretical knowledge, I only started practical application a few days ago."
Aizen's brow twitched slightly.
"Only a few days?"
"Yes."
"And Black Coffin? Have you studied it before?"
"You must be joking, Lieutenant Aizen. Today is my first time encountering it."
Aizen fell silent and gave a slight nod.
He turned around and walked back to the lab table.
At this moment, Aizen's state of mind was far less tranquil than his outward appearance suggested.
He recalled his own experiences when he was practicing Incantation Abandonment.
Aizen's understanding of Kido was incredibly deep, and his progress had been rapid—enough to be called a rare prodigy seen only once in a century.
Even the current Grand Kido Chief was hardly someone he held in high regard.
But Ren, who was still practicing in the corner of the cave, was visibly and steadily improving his success rate.
After every failure, he would adjust the flow of his spiritual pressure and correct it in his next attempt.
That speed of adjustment, that control over spiritual pressure, that understanding of spell construction...
It was almost exactly the same as Aizen's own.
Aizen's eyes narrowed slightly.
To have it so deeply engraved in his mind and applied in practice after just one explanation.
Aizen also recalled how Ren's spiritual pressure had suddenly surged under immense pressure earlier.
Looking at it this way, it wasn't just Ren's unique constitution—the coexistence of Soul Reaper and Hollow spiritual pressure—that was worth researching.
Ren's own personal secrets were equally worthy of in-depth observation.
This terrifying learning efficiency...
It was as if his very body was born for the sole purpose of mastering power.
Aizen slowly exhaled a breath.
Then, he raised his head and looked at Ren again.
The corners of Aizen's mouth curled up slightly.
*Interesting.*
He stood up and walked toward Ren.
His pace was slow, every step carrying a leisurely rhythm, as if he were just casually strolling through the cave.
But his gaze remained fixed on Ren.
"Hado #90. It seems you can release it stably now."
He stopped in front of Ren, his tone calm, betraying no emotion.
"Thank you for your guidance, Lieutenant Aizen, but I still have a long way to go."
Aizen did not reply to that.
He simply looked at Ren quietly, his gaze lingering on his face for a moment before shifting away.
"Beyond Hado #90, there are even more advanced destructive spells."
Aizen turned around to face Ren.
"Do you want to learn them?"
Ren nodded without hesitation.
"I do, but... I think I should learn some more fundamental destructive spells right now."
"Even if I learned those high-level spells, with my current amount of spiritual pressure, it would be very difficult to use them as conventional attack methods."
Aizen smiled.
The smile was faint, yet it carried an indescribable meaning.
"Well said."
Aizen raised his hand.
No incantation. No hand seals.
Spiritual pressure gathered in his palm. The power was immense and stable, carrying a heart-palpitating sense of oppression.
"Hado #63: Raikoho. A destructive spell of this level should be quite suitable for you at present."
He waved his hand.
A beam of light shot from his palm, then exploded with a deafening roar, leaving a scorched mark deep within the cave.
Aizen lowered his hand and turned to look at him.
"Did you see that clearly?"
Ren shook his head.
"I saw it clearly, but I don't fully understand it."
Aizen seemed satisfied with his honesty.
Subsequently, Aizen gave Ren a detailed explanation of the essentials of gathering spiritual pressure and guiding the incantation text for Raikoho.
After breaking down the core content and the techniques for Incantation Abandonment, he looked at Ren.
"Give it a try."
Ren took a deep breath and raised his hand.
Spiritual pressure gathered in his palm, thick and stable.
After a few failures and Aizen's corrections on certain details...
Raikoho successfully manifested in Ren's palm.
Blue lightning shot from his hand and exploded with a roar in the distance.
Although the power was far inferior to Aizen's demonstration just now, it was indeed a success.
Aizen stood to the side, saying nothing.
He remained silent for a long time.
Then, he spoke slowly.
"Raikoho. Have you learned it before?"
Ren shook his head.
"No, today is my first time seeing it."
Aizen nodded.
"Not bad."
Then, Aizen pondered for a moment and spoke softly.
"Ren, you are very special."
"To be honest, the things I am teaching you are not, in my eyes, things that can be mastered simply."
"The speed at which you comprehend and master them truly surprises me."
He looked into Ren's eyes.
Ren fell silent.
"You flatter me, Lieutenant Aizen."
"I'm just... relatively good at learning."
Aizen smiled.
"Good at learning?"
He repeated those words, as if savoring their meaning.
Then, he shook his head.
"You are very special, Ren."
"I have seen many talented people, but they all share one common trait: they all eventually hit their limits."
"No matter how high their talent, there is always a ceiling, a limit they cannot surpass."
He paused.
"I am very curious to see where your limit lies."
Ren did not speak; he simply looked at Aizen quietly, his face devoid of any expression.
*This man was even sharper than he had imagined.*
Seeing his silence, Aizen suddenly smiled.
"Relax, there is no need to be afraid."
He turned around and walked back to the lab table.
"Everyone has their own secrets. As long as your secrets do not interfere with our goals, I will not pry."
He picked up the notebook, flipped to the page he had just been writing on, and glanced at it.
Then, he closed the notebook.
"Continue practicing."
He raised his head and looked at Ren.
"I look forward to your progress."