It's been months since he obtained Hitsugaya's [Child of Kirin].
In these few months, his rate of progress has surpassed the past decades.
He naturally mastered his Zanpakutō's Shikai.
A Zanpakutō's Shikai requires "manifestation" and "Kaigō (Release Call)," while Bankai requires "materialization" and "subjugation."
Manifestation means aligning one's spirit with the Zanpakutō to converse with it.
Although still rudimentary, Yoshio has indeed reached that realm.
Thus, he can wield his Zanpakutō's power!
"Tranquil in three voids, Jigoku Zoku."
That is the release command for his zanpakutō; the ability is simple.
It is—
Exile.
Banish the enemy's spiritual will into the void and cast them into the Lonely Hell!
No one else exists—only the self—enduring endless solitude.
Of course, "nothing exists but oneself" doesn't mean there is literally nothing.
What is loneliness?
There is no absolute definition; everyone experiences it differently.
Therefore, the Lonely Hell has no fixed location, and its torments constantly change.
Some are crushed between towering mountains; some are trapped within rock; some are frozen upon frigid snowy peaks; some sink into pitch-dark abyssal seas; others burn amid raging fire and oil.
In such places, one will forever feel absolute isolation.
That is Jigoku Zoku's power.
So, when Yoshio drove his Zanpakutō into Metastacia's brain, that force of loneliness instantly invaded its spirit.
It has nothing to do with where he physically is; it throws the entire spirit into the Lonely Hell.
Because no matter how many clones Metastacia splits into, there is only one spirit controlling them. Destroy that one spirit, and all clones cease moving.
In that moment, Metastacia's will fell completely into the Lonely Hell woven by Jigoku Zoku—ten years, a hundred, a thousand, ten thousand—it will be bound by "loneliness" forever.
After confirming his Zanpakutō's power had taken effect, Yoshio gently drew the blade out.
The [Black Sun] behind him gradually dissipated. In the process of dealing with this Third Squad Captain, the [Black Sun]'s power had been exhausted.
Even after pouring spiritual pressure into it for so long, it amounted only to a single Captain-class heavy blow…
If Metastacia hadn't forcibly parasitized his body, that [Black Sun] absolutely wouldn't have killed a captain.
"You actually did it."
Aizen praised from the side. "You saved your 'friend.'"
He was becoming more and more interested in Yoshio's abilities.
Back then, Yoshio used a special kidō—a ray with immense penetration and destructive power—to kill Metastacia.
And now, before his eyes, he had again unleashed a special kidō—vast spiritual pressure condensed into a Black Sun, hissing as it burned, devouring and dissolving everything before it.
This is not a power an ordinary shinigami could wield; even for a Captain-class entity, creating such a formidable kidō would be difficult.
"I… I don't want to fight."
Walking past the Third Squad Captain's corpse, Yoshio said, "Every time I draw my sword, I am strangling a living life."
"Every life has value."
"…Didn't expect you to be so kind. Kind people shouldn't befriend hollows."
"No." Yoshio walked to Aizen's side; by now he had sheathed his Zanpakutō.
"It's just that every life I take means one fewer subject to observe."
"Observe?"
"Yeah. Everyone's personality differs; their thoughts differ. Even if next they will 'do this,' why do they do it? Aren't you curious, Captain Aizen?"
"I… I have no interest in observing ants. I only observe those who interest me," Aizen said with a smile.
"Yes." Yoshio looked at Aizen and smiled as well.
"So I'm searching for people who interest me. Everyone has that potential."
"Unfortunately, most people are too boring. Observe for a while and you find that though they seem different, they are actually the same."
"Humans are both complicated and simple. Over time, it becomes exhausting."
After he finished, Yoshio's heart gave a little jolt.
Because at this very moment, Aizen's favorability toward him actually rose a bit.
His favorability had now climbed to thirty, about the same as Nelliel's.
So-called favorability, before sixty, doesn't necessarily signify "friendship."
When you pay special attention to someone and feel that some of what they say makes sense, a certain level of favor naturally arises.
Or put another way, once you pay special attention to someone, "liking" has already begun.
And clearly, what Yoshio just said struck Aizen as interesting—or rather, made him more intrigued by Yoshio—thus raising his favorability to thirty.
But getting Aizen to regard someone as a friend is still extremely difficult.
If not for Aizen's Souls Ability being so compelling to Yoshio, he really wouldn't want to say so much in front of Aizen.
Of course, sometimes it isn't that he wants to talk, but that he has to.
From the moment Aizen set his sights on him, noticed him—he had no choice.
He had to wear this disguise; otherwise, he wouldn't have lived to now.
"Captain Aizen!"
Suddenly, many shinigami voices rang out from not far away, followed by dense footsteps. People emerged from the forest and immediately saw Aizen and Yoshio.
Seeing Tanimoto Toru and the others among the crowd, Yoshio breathed a sigh of relief.
They weren't actually dead.
It wasn't because Aizen held back, but because Yoshio had previously banished Metastacia with Jigoku Zoku, causing the parasitized shinigami attacking them to become useless.
"Ca… Captain?!"
Among the crowd, someone spotted the Third Squad Captain lying on the ground with a Zanpakutō stuck in his head and cried out in shock—it was clearly someone from the Third Division!
"Was… was this done by Captain Aizen?"
"I'm very sorry. The hollow and his soul had fully fused; even I couldn't separate them."
Aizen showed a trace of regret, then said, "After I severely wounded him, he slipped away while I was distracted. By the time I caught up here and found Yoshio, the battle was already over."