Kaien Shiba  

"No, Kukaku, I believe Captain Ailin speaks sense." Kaien Shiba rested his hand gently on his sister's head, his voice a soothing murmur. "Compared to the Shinigami of the Seireitei, our Shiba clan's legacy has fallen behind."

He continued, "Remember Lady Yoruichi?"

"Oh? That woman?" Kukaku's nose wrinkled at the mention of the dark-skinned woman.

Despite being of similar age and descending from the Five Great Noble Houses, Kukaku always found herself soundly defeated whenever she sparred with Yoruichi Shihōin. Worse, she couldn't even gauge how much effort Yoruichi exerted during their matches.

"Yes," Kaien affirmed with a nod. "Kukaku, in terms of talent, I believe you are no less than Lady Yoruichi."

"However, Lady Yoruichi has inherited the complete legacy of the Shihōin clan, while our Shiba clan... by our generation, even the Kidō incantations are incomplete..."

A shadow of worry crossed his face. "If we don't seek change, the Shiba clan will truly decline in our hands..."

Hope flickered in his eyes. "As Captain Ailin said, our Shiba clan isn't without foundation in the Seireitei. With Uncle Isshin as the Captain of the 10th Division, any difficulties I encounter in the Seireitei can surely be resolved with his strength and status."

"With access to the Seireitei's training resources, I'm confident I can reach captain-level strength within a century."

A determined glint appeared in his eyes. "By then, with my influence and Uncle Isshin's, we can restore the Shiba clan to its former glory and reclaim what we've lost!"

"But brother, if those people discover your talent, they won't simply watch the Shiba clan rise again," Kukaku countered, her voice laced with concern.

Despite the enticing future Kaien described, her family's safety remained her top priority. "The dangers you'll face will be far greater than you imagine."

"But Kukaku..." Kaien's voice softened. "If I don't face these dangers, will you? Or Ganju? Or the next generation of the Shiba clan?"

"This is the best time," he insisted. "If we miss this opportunity, how long will it take for the Shiba clan to return to the Seireitei?"

Kaien's gaze turned distant. "I know our clan's ancestral teachings urge us not to return to the Seireitei but to expose the sins of the Five Great Houses and bring them to justice..."

He looked at his sister with unwavering resolve. "But all of that requires the Shiba clan to possess both strength and influence."

"Otherwise, even if we reveal their crimes, who would believe us?"

Kaien held back one final thought, echoing Captain Ailin's words. Without strength, the Shiba clan, burdened by generations of resentment towards the Five Great Houses, would never be allowed to rise again. Any sign of their resurgence would be met with swift and brutal suppression from the other noble houses.

...

After spending most of the night in discussion, Kaien finally convinced Kukaku to allow him to enter the Seireitei and become a Shinigami.

To protect the main house from retaliation during Kaien's absence, Kukaku took Ganju and relocated. Without her guidance, not even Kaien could find their new residence.

...

Ailin's plan to search for promising "children" in the Rukongai was cut short. He couldn't possibly explore every district within a few days.

His plans were further interrupted by the arrival of Nanao Ise.

Haruko, delighted to reunite with Nanao after a long time, spent hours catching up with her.

Once they had finished reminiscing, Ailin took Nanao to Urahara's abandoned underground base. After all, it was the most suitable location for Kidō training.

...

"Wow..." Nanao's jaw dropped as she beheld the underground base for the first time. She never imagined such a place existed within the Seireitei.

Seeing her expression, even Ailin couldn't help but grin with pride. He finally understood why Kisuke Urahara enjoyed observing people's reactions when he brought them to his secret base.

Creating something so awe-inspiring was indeed addictive.

"So, what do you think? Pretty impressive, right?" Ailin gestured towards the ceiling. "It took me almost half a night to create this sky, and it looks almost identical to the real one outside of Soul Society."

"Wow, Uncle Ailin, you're amazing!" Nanao's eyes sparkled with admiration.

"Hehe, of course," Ailin chuckled, feeling even more smug. "But if you train hard with me, Nanao, you'll be able to do this one day too."

He knew Nanao possessed exceptional talent for Kidō. In the Thousand-Year Blood War, she even managed to temporarily halt Haschwalth's advance with a barrier.

"Yes!" Nanao nodded vigorously. If she couldn't achieve this level under Uncle Ailin's guidance, she might as well give up and avoid tarnishing his reputation as a mentor.

Ailin was pleased to see her confidence. Reishi responded to one's will. Without self-belief, even with immense spiritual pressure, one's strength would remain underwhelming.

The most prominent example of this was Ichigo Kurosaki, the protagonist of the Shinigami world. When he had a clear goal, such as saving Rukia, Ishida, Orihime, Chad, the residents of Hueco Mundo, or the people of the Seireitei, Ichigo could unleash his full potential.

However, once his goals were achieved, Ichigo, although still strong, lost that sense of unwavering determination.

Even Aizen had pointed this out during their first encounter after Ichigo returned from Hueco Mundo. Ichigo held no personal grudge against Aizen, and his attacks lacked killing intent.

Before the Thousand-Year Blood War, when Ichigo and his friends faced a group of Hollows, merely Gillians, Ichigo resorted to using Bankai and Getsuga Tenshō.

Byakuya Kuchiki, too, had been affected by his inner conflict during his first fight with Bankai Ichigo, ultimately leading to his defeat.

...

"Nanao, as your Ise family has guarded the sacred 'Eight Mirror Sword' for generations, your Zanpakuto, in a way, is the 'Eight Mirror Sword' itself," Ailin explained.

"However, due to its loss, you've become a Shinigami akin to the Kidō Corps, unable to wield a Zanpakuto."

"Despite this, you must still learn some basic swordsmanship. After all, who knows when your family's heirloom might suddenly reappear, right?"

"Yes." Although Shunsui Kyoraku often reminded Nanao to focus on living her own life and avoid using the Ise clan's heirloom, as the sole survivor of her family, Nanao couldn't bear the thought of letting the Ise clan fade into obscurity.

She would avenge her parents.

She would also recover the Eight Mirror Sword.

"Our training will prioritize Kidō, with Shunpo as a secondary focus, and swordsmanship as the least important. What do you think?" Ailin asked.

"I'll follow your arrangements, Uncle Ailin."

Ailin nodded. Nanao wasn't a prodigy with independent thinking like Gin Ichimaru, nor did she possess the combat intelligence to adapt and improvise like Byakuya Kuchiki.

She was more like a diligent student who relied on memorizing countless exam questions and solving them through experience, somewhat rigid in her approach.

Therefore, Ailin planned to start by having Nanao master all the Kidō spells within her current reiatsu capacity.

Then, through combat training, he would help her apply those Kidō techniques with proficiency.

Ailin believed that under his personalized training, tailored to their individual styles, Nanao would be able to find perfect solutions to any challenge she encountered in the future.

To improve her adaptability and survival rate, Shunpo training was also essential for Nanao.

...

"Hey, did you hear? Apparently, another prodigy has emerged in the Shin'ō Academy this year..."

"They say he already possesses fifth-level spiritual pressure upon enrollment."

"Yes, I heard his name is Kaien Shiba?"

"Shiba? I wonder if he's related to Captain Shiba of the 10th Division..."

"I'm so envious."

Fifth-level spiritual pressure was equivalent to the level of a seated officer within the Gotei 13. It was practically the limit for ordinary Shinigami, a level many struggled to achieve.

The minimum requirement to join the Gotei 13 was tenth-level spiritual pressure.

Seventh-level and above were considered "elite Shinigami."

With fifth-level spiritual pressure and a successfully nurtured Zanpakuto, one could easily reach the rank of a seated officer.

Fourth-level was sufficient to serve as a vice-captain in any division.

Third-level and above marked the realm of captains.

Kaien Shiba's enrollment had undoubtedly caused ripples within the otherwise peaceful Soul Society.