Yoruichi’s Concern  

"You know very well why you were imprisoned. If I ever discover that you've targeted those I care about again, then I'll personally eliminate you, Aizen… Your soul won't even have the chance to reach Hell!"

Aizen's smile faltered for a moment. Most people in this world were aware of Hell's existence, but few knew its true nature. Aizen, however, was among those few.

The events of Soul Society were recorded within the "Great Spirit Book Gallery," and Aizen, wielding Kyōka Suigetsu, had been a frequent visitor. He had uncovered many of Soul Society's hidden secrets within its archives, including the "Ōken," the key to the Soul King Palace, and the method for its creation.

Hell had been born alongside their world. However, the "god" who had created the Soul Society had abandoned it midway, leaving it incomplete. In that primordial era, chaos reigned. Life and death were intertwined, with no clear boundary between them.

Then, a soul had fallen, transforming into a Hollow. It began to devour other souls, growing stronger with each consumption. Sadly, at that time, neither the souls of the living nor the dead possessed any power to resist its hunger.

If this continued, the Hollow would eventually consume all the souls in existence, transforming the world into a single, massive Hollow.

Perhaps it was the world's instinct for self-preservation, but just as the Hollow had devoured nearly half the souls in existence, a "god" was born—the Soul King.

The Soul King, a manifestation of the world's will, used his Quincy powers to vanquish the Hollow, then with his "Almighty" ability, he created the Human World, Hueco Mundo, and Soul Society, separating life and death.

For a time, they believed the world was complete. However, the founders of the five great noble clans, who had received their power from the Soul King, ultimately betrayed him.

Only after sealing him, transforming him into the linchpin that stabilized their world, did they discover that another realm existed—Hell.

Hell was a reflection of their world, a dark mirror image. Initially, it had been small, an insignificant speck in the grand scheme of existence.

But Hell could grow, fueled by the souls of the wicked.

While its growth was slow, limited by the number of evil souls it could consume, over time, it had become a force to be reckoned with.

Over a million years, Hell had expanded to half the size of Soul Society.

Moreover, to accelerate its growth, Hell's will had subtly influenced the Soul Society, most notably in the "Captain's Funeral" ritual.

The Captain's Funeral was a ceremony performed for those with captain-level spiritual pressure and above. Their reiatsu was so immense that their bodies wouldn't naturally dissolve into reishi particles upon death.

Thus, after a series of rituals, the deceased captain's body would be cremated, allowing their spiritual energy to return to the world.

However, unknown to the Shinigami, the Captain's Funeral didn't actually return the captain's reiatsu to the world. Instead, the ritual served as a conduit, funneling their spiritual energy into Hell.

Even Aizen had been unaware of this secret.

But he knew that Hell represented the world's eventual demise.

One day, Hell would consume all the souls in existence, transforming the world into an extension of itself.

This process was irreversible.

Aizen, with his ambition to become a "god," had never considered the possibility of his own death.

But now, Ailin had reminded him that he was powerless.

Twenty years ago, Aizen had been defeated, his life spared only because of Ailin's whim.

Even now, having achieved the limit of a Shinigami's power, Aizen didn't believe he could defeat Ailin.

If he wanted to stand on equal footing with Ailin, he needed to become stronger.

"Don't worry, Captain Ailin. I don't intend to die before I achieve godhood."

"Tsk…" Ailin clicked his tongue, then opened a spatial portal before Aizen.

"Leave, Captain Aizen. I hope you can fulfill our agreement."

"Of course. Isn't that why you released me?"

…

Ailin woke from his slumber, his hand gently stroking Haruko Kuchiki's hair. He rose from the bed and stepped out into the Kuchiki estate's courtyard.

Gazing at the night sky, his eyes seemed to pierce through the seventy-two barriers separating the Seireitei from the Soul King Palace.

Since awakening to his "sword" essence, Ailin's strength had been growing exponentially.

Now, he couldn't even fathom the extent of his power.

This uncertainty, this inability to gauge his own strength, gnawed at him.

He yearned for a worthy opponent, someone who could help him recalibrate his power, to understand where he stood in the grand scheme of existence.

But how many individuals could truly challenge him now?

Aizen, after merging with the Hōgyoku; Ichibei Hyosube, the founder of the Royal Guard; Yhwach, before absorbing the Soul King; Ichigo Kurosaki, wielding his dual-wielded Bankai…

Those four were the only ones he could consider worthy adversaries.

For now, the other three hadn't yet reached their full potential. Only Hyosube could truly test his strength.

However, Ailin wouldn't fight Hyosube until he had defeated Aizen.

He had ranked those four opponents based on their strength.

Aizen, even after fusing with the Hōgyoku, was weaker than Hyosube. Hyosube was weaker than Yhwach before he absorbed the Soul King. Yhwach, before absorbing the Soul King, was weaker than Ichigo Kurosaki with his dual-wielded Bankai.

He only had one chance to defeat each of them.

Ailin feared that once he defeated Hyosube, he might lose interest in battling Aizen, robbing him of the thrill of combat.

He now understood why those villains who had achieved unrivaled power were so keen on nurturing their opponents.

"The dragon slayer eventually becomes the dragon…"

"Am I the dragon now?"

"Will you be the one to slay me, Aizen, or will you become the fuel for my further ascension?"

…

A black cat emerged from a distorted spatial rift, surveying its surroundings. It locked onto a specific direction and sped off, its movements too swift for the human eye to follow.

Fifteen minutes later, the cat arrived at a scene of devastation. Burned houses, a shattered shrine, and the lingering scent of blood—the aftermath of a fierce battle.

"It's… true…" A deep voice rumbled from the cat's throat. Anyone witnessing this would have been terrified.

A talking cat?

However, those who knew this cat wouldn't have been surprised.

It was Yoruichi Shihōin, the former captain of the 2nd Division.

While residing in the World of the Living, Yoruichi had received information through the Shihōin Clan's channels that certain noble families in the Soul Society had launched an attack on the Shiba Clan, dragging Ailin's disciple, Rukia Kuchiki, into their conflict.

Despite her current feline form, Yoruichi couldn't help but sigh. She knew about the feud between the four great noble clans and the Shiba Clan. As the twenty-third head of the Shihōin Clan, she had even uncovered the location of the Shiba Clan's main family.

If her ideals aligned with those of her ancestors, she would have personally led the attack, eradicating the Shiba Clan.

After all, when she had discovered their location, both Kaien and Kukaku Shiba had been mere youths, their strength comparable to that of ordinary Shinigami.

However, having learned of the Shiba Clan's history, Yoruichi had found herself admiring their unwavering dedication to truth and justice.

She had even barged into their home, demanding to be Kukaku's friend.

Though their relationship wasn't particularly close, they could at least be considered "friends."

Now, her own clan had attacked her friend, dragging Ailin's disciple into their conflict. It was giving her a headache.

The thought of Ailin's reaction troubled her even more.

Over the years, Yoruichi and Kisuke Urahara had analyzed Ailin extensively. Based on their century-long friendship, they had concluded that he was both predictable and unpredictable.

Predictable because he cared deeply for those close to him. As long as they were safe, Ailin wouldn't do anything rash.

Unpredictable because of those very same people.

When Haruko's soul had been in jeopardy, Ailin, believing Urahara could help, had sought him out, resorting to threats to ensure her safety.

Now, the Shihōin Clan's assassins had attacked Ailin's disciple. The consequences would be dire.

However, Yoruichi decided to address that problem later. For now, she had to check on her "friend."

Swoosh! Swoosh! Swoosh!

Guided by Kukaku's spiritual pressure, Yoruichi sprinted through the ruins, leaping across rooftops and navigating the debris-strewn streets. She eventually found Kukaku within a partially collapsed shrine.

"Well, well, long time no see, Kukaku."

Yoruichi leaped down from a beam, landing before her friend.

"Haaaa!"

Kukaku's eyes narrowed at the sight of the black cat. She channeled her spiritual pressure, throwing a punch towards Yoruichi.