The Ten-Year Battle, Once Again  

Sōsuke Aizen had lived up to Shinji Hirako's expectations. Within a few years, he had manifested his Zanpakutō, mastered its initial release, and become the lieutenant of the 5th Division.

Shunsui Kyōraku narrowed his eyes. It seemed that it was around the time Aizen had publicly revealed his mastery of Shikai that Shinigami, and even students at the Shin'ō Academy, began showcasing their Zanpakutō abilities more openly.

As for Ailin, the captain of the 11th Division… Shunsui couldn't quite understand him.

For decades, Ailin had kept a low profile. Shunsui hadn't noticed anything that set him apart from the most ordinary Shinigami.

Like Aizen, Ailin's rise to power had been sudden. However, while Aizen had been directly promoted to lieutenant by Hirako, Ailin had earned his position as lieutenant of the 2nd Division by defeating Marenoshin Ōmaeda in front of over two hundred Shinigami, including the captain.

Later, Ailin had met the eldest daughter of the Kuchiki Clan by chance. While escorting her home one evening, he had encountered Ginrei Kuchiki and Koga.

In the end, Ailin had successfully resolved Koga's rebellion and become Ginrei's son-in-law. A year later, he had been appointed as the captain of the 6th Division…

Aizen and Ailin…

Ailin had told Shunsui that Aizen was the mastermind lurking within the Soul Society. While Aizen hadn't explicitly revealed his intentions, his actions, both overt and covert, seemed to be directed against Ailin.

Their conflict had seemingly drawn the entire Soul Society into its web.

Although both Aizen and Ailin had been quiet in recent decades, Shunsui didn't believe their rivalry had truly ended.

The current peace was likely just a temporary lull, a period of preparation for their next clash, a clash that would undoubtedly shake the Soul Society to its core.

Perhaps even Captain-Commander Yamamoto wouldn't be able to quell the storm.

In recent years, Aizen still visited the Shin'ō Academy two or three times a year to answer students' questions and demonstrate his Zanpakutō abilities. Shunsui occasionally met with him there.

However, Ailin rarely left the Kuchiki Manor. Unless Shunsui invited him for drinks, Ailin spent most of his time at home. This made it difficult for Shunsui to learn more about him.

Even the Onmitsukidō couldn't gather much information within the heavily guarded estate of a prominent noble clan.

So, Shunsui had decided to indirectly learn about Ailin through the person who had the most contact with him - Rukia Kuchiki.

Shunsui remembered Rukia for two reasons.

First, she bore a striking resemblance to Byakuya's late wife, Hisana Kuchiki. According to Shunsui's investigation, Rukia was Hisana's younger sister.

Second, Shunsui had been present when Ailin had taken Rukia as his disciple. He had even served as a witness.

Shunsui believed that Rukia might hold the key to understanding Ailin.

Coincidentally, his good friend, Jūshirō Ukitake, had told him that Byakuya had requested him to recruit Rukia into the 13th Division as an ordinary Shinigami.

Shunsui sensed that something was amiss.

With Ailin's teaching abilities, Rukia couldn't possibly remain an ordinary Shinigami.

Even if she wasn't as talented as Hitsugaya, after six years of training, she should have at least reached the level of an elite Shinigami. In a few years, she would likely become a seated officer, perhaps even a lieutenant.

Why would Byakuya want her to remain an ordinary Shinigami?

Could it be that Byakuya sensed something about Ailin's intentions and was trying to suppress Rukia's growth to challenge Ailin's authority?

Intrigued, Shunsui had come to observe Rukia.

Upon seeing her, his suspicions deepened.

Rukia possessed a fifth-level spiritual pressure.

It was a level that could easily place her within the top ten seated officers.

If her Zanpakutō ability was strong enough, with a fifth-level spiritual pressure, she could even become a lieutenant.

Moreover, Rukia was still in her prime. Within a few years, her spiritual pressure would likely rise to the fourth level, solidifying her qualifications for lieutenant.

Why would Byakuya insist on her remaining an "ordinary Shinigami?"

"He's still too weak…" Shunsui sighed inwardly.

If he possessed the same level of power as Captain-Commander Yamamoto, things would be much easier.

However, glancing at Ukitake beside him, he felt a sense of reassurance.

Thankfully, with Ukitake's "Mimihagi" power, as long as Ailin and Aizen didn't join forces, any crisis in the Soul Society wouldn't escalate beyond control.

Still, he needed to become stronger.

He couldn't afford to slack off any longer…

Under the eager gazes of the academy students, all eighteen graduates, including Rukia, successfully joined their chosen divisions.

Kira Izuru joined the 4th Division.

Momo Hinamori joined the 5th Division.

Renji Abarai joined the 11th Division.

Rukia, after receiving a personal invitation from Captain Ukitake of the 13th Division and considering both Shunsui's thoughts and Byakuya's wishes, decided to forgo joining the 11th Division. She became an ordinary Shinigami within the 13th Division.

…

"Hey, Ikkaku, where are you all going?"

In the evening, Renji, wiping the sweat from his brow after a day of training, was about to head back to his dormitory when he saw the members of the 11th Division rushing out. Curious, he followed them, catching up to Ikkaku Madarame.

Nearly a year had passed since Renji had joined the 11th Division.

During that year, Ailin had kept his promise, appointing Ikkaku Madarame as Renji's mentor.

Ikkaku and Renji proved to be a good match.

Ikkaku was a self-taught fighter from Rukongai, and Renji, having spent his childhood there, also possessed a wild, relentless fighting style.

Ikkaku's Zanpakutō, Hōzukimaru, could transform into a three-section staff, while Renji's Zabimaru could extend its segments, giving them a certain degree of similarity.

Moreover, Ikkaku was also a battle maniac, relishing combat. He held nothing back while teaching Renji, focusing primarily on practical experience.

Of course, this suited Renji perfectly.

For someone as straightforward as Renji, learning through combat was far more effective than solitary training.

As a result, after only a year of training under Ikkaku, Renji's strength had increased several fold. He was now considered an elite Shinigami within the 11th Division.

After getting to know Renji, Ikkaku found him to be a kindred spirit. He felt that the title "teacher" was too formal and asked Renji to address him as "big brother" instead.

"Oh, Renji. I almost forgot to tell you. Today's the day Captain Zaraki fights Captain Ailin. We're all heading to Rukongai to watch."

"What? Captain Zaraki is fighting Captain Ailin?" Renji exclaimed.

During his year in the 11th Division, he had learned many things, including the fact that to become the captain of the 11th Division, one had to challenge the current captain in front of over two hundred Shinigami.

He had also accompanied Zaraki on several missions, witnessing a glimpse of his captain's true power. Even that glimpse was enough to leave Renji trembling.

Zaraki was the strongest being he had ever encountered.

With his immense reiatsu and overwhelming swordsmanship, Renji couldn't imagine anyone who could match him.

Now, he was going to fight Rukia's teacher.

Renji couldn't help but feel a sense of unease.

With Zaraki's strength, if he killed Ailin, what would Rukia think of him, a subordinate of the man who had slain her teacher?

"Ikkaku, is this fight between Captain Zaraki and Captain Ailin dangerous?" he asked.

"Don't worry, Renji. Captain Zaraki and Captain Ailin fight every ten years. Captain Ailin knows his limits and won't kill Captain Zaraki," Ikkaku reassured him, mistaking Renji's concern for worry about Zaraki's safety.

They had felt the same way at first.

After all, since Ailin rarely involved himself in division affairs, it was Zaraki who led them in battle.

So, while they all knew Ailin was stronger, they felt closer to Zaraki.

Perhaps it was Zaraki's pure desire for combat that drew them to him.

"Huh?" Renji's breath hitched.

What had Ikkaku just said?

Ailin knew his limits and wouldn't kill Zaraki?

Was Ailin that strong?

Renji suddenly remembered that the captain of the 11th Division was, in fact, Ailin.