Shinigami in the Ninja World

The courtyard was in a flurry of activity.

The younger Shinigami were scrambling, while those with more experience remained calm.

As for the captains, they barely reacted.

Losing two captains... compared to some past incidents, it wasn't too severe. However, the nature of this event was different.

A Shinigami colluding with the Hollows—this was unprecedented.

"Naruto," the Captain-Commander appeared with a Shunpo, his expression serious. "On the way here, Shunsui told me about what happened."

"You know the most, so explain it to me properly."

Naruto nodded. "Here?"

"Let's go to the barracks," the Captain-Commander shook his head. "Leave these matters to the lieutenants for now."

"It's better that a human stays out of Soul Society's affairs," the Captain-Commander objected with a stern, rigid expression.

Naruto responded softly, "It's not about involving him; he's already a part of this."

"Aizen's objectives include him."

The Captain-Commander raised an eyebrow, looking Ichigo over. "If that's the case, then bring him along."

The orange-haired boy felt tense.

At the barracks of the 1st Division.

The eleven current captains gathered, along with Ichigo.

"Naruto, what is Aizen's goal?" the Captain-Commander asked.

Naruto replied, "He wants to break the boundary between Shinigami and Hollow. According to him, he seeks to evolve into a higher form of life."

"And he wants to kill the Soul King to become the new ruler."

"Such treasonous ambition!" Sajin Komamura couldn't hold back and shouted.

The Captain-Commander's sharp gaze focused on Ichigo. "And what connection does this boy, this Ryoka, have with Aizen?"

"He seems to be Isshin Shiba's son," the Captain-Commander continued. "Is the Shiba family involved with Aizen?"

Naruto shook his head firmly. "No, this has nothing to do with the Shiba family. It's because of Ichigo's unique nature."

He paused.

"As for the secret of the Soul King, Captain-Commander, you should be aware."

The Captain-Commander nodded.

Naruto glanced around the room, his eyes passing over the other captains. Besides Unohana Retsu, Shunsui Kyōraku, Jūshirō Ukitake, Byakuya Kuchiki, and Mayuri Kurotsuchi, the rest of them seemed confused, clearly unaware of the situation.

"This is a significant matter, so I won't go into too much detail," Naruto took a deep breath. "The existence of the Soul King stabilizes the three worlds."

"And he is controlled by the Five Great Noble Families."

Ichigo froze.

He latched onto a specific word: controlled.

What does that mean...? He also remembered Aizen's parting words, calling him the Keystone.

Was becoming the Soul King not a good thing?

"If Aizen wants to become the ruler, he needs a new king," Naruto continued. "And the candidate he's chosen is Ichigo Kurosaki."

Ichigo shouted in disbelief, "A new king?"

"Me?"

I'm just a normal high school student, decent at studying, with some considerable spiritual power. But beyond that... what makes me so special?

Surely, Uncle Naruto is much stronger than me, right?

"Why him?" the Captain-Commander asked, sharing Ichigo's confusion.

Naruto answered directly, "Because of his power."

"Inside Ichigo, there isn't just the power of a Shinigami—he also has Hollow and Quincy powers."

"He even has the potential to become a Fullbringer."

"He possesses every type of power in this world. Though his abilities may not be fully developed yet, conceptually, he's closer to the Soul King than any of us."

Silence fell over the room.

Some didn't fully grasp the specifics, but they understood the gravity of Ichigo's importance.

Those who did understand wore grave expressions.

"Naruto, you certainly know a lot," the Captain-Commander sighed. "In that case, we'll have to take some precautions with Ichigo..."

Before he could finish speaking, the Captain-Commander turned his head toward the door.

Naruto noticed the presence even earlier—an immense and familiar spiritual pressure was approaching.

The door burst open.

"If you think all Kurosaki needs is protection, you're mistaken," said the intruder with firm resolve. "He needs training. He needs to become stronger."

Everyone turned to look at her.

Soi Fon gritted her teeth. "Yoruichi Shihōin!"

"Even after all these years in the human world, you're still so disrespectful," the Captain-Commander scolded. "Yoruichi, how dare you return here."

Yoruichi smirked playfully, but her expression grew serious when her eyes met Naruto's. She quickly averted her gaze, clearly feeling guilty.

"Why does Ichigo need to become stronger?" Naruto asked.

Yoruichi looked at Soi Fon. "Because of the Arrancar."

"When an Adjuchas evolves into an Arrancar, it reaches captain-level strength."

"If it's a Vasto Lorde that evolves, it will take a captain of my caliber to handle it."

She paused, her tone becoming even more severe. "We don't know how many subordinates Aizen has in Hueco Mundo."

"But given his willingness to use Vasto Lorde as test subjects..."

"I fear the number is not small."

"That's why we need strength."

"Kurosaki has achieved his current power in just a few months. He could quickly reach captain-level strength."

"And like Naruto said, with the different types of power inside him, if he can master them all, he might even surpass that."

The Captain-Commander said nothing, glancing at Ichigo.

The orange-haired boy stood up, speaking resolutely. "I want to become stronger!"

"I want to protect myself!"

Yoruichi's tone softened. "That's why you should leave him to me."

"No," Naruto interrupted her.

Yoruichi froze.

Naruto's voice remained calm, but his spiritual pressure created a barrier between Yoruichi and Ichigo. "You're not trustworthy right now."

The Captain-Commander raised an eyebrow, his gaze sharp as he focused on Yoruichi.

"Come on, Naruto," Yoruichi said with a wry smile, raising her hands. "Why wouldn't we be trustworthy?"

Naruto narrowed his eyes. "Ichigo's very existence..."

"While it was part of Aizen's plan, Kisuke Urahara also had a hand in it, didn't he?"

Yoruichi looked down, unable to refute the truth.

After a long pause, she continued. "It was only through Ichigo's existence that we were able to draw out Aizen."

"And now, entrusting Kurosaki to us is the only reasonable choice."

Yoruichi took a deep breath, playing her last card. "We can help Kurosaki achieve Bankai in the shortest possible time."

"And the other powers inside him..."

"You know, Naruto."

"We can at least help him master the Hollow part."

Naruto's eyes narrowed, deep in thought. "Bankai in the shortest time?"

"Your powers are unique, which is why Urahara didn't offer it to you," Yoruichi nodded.

Mayuri Kurotsuchi tilted his head, curious. "Are you referring to the device known as Tenshintai?"

"That could indeed shorten the time needed to learn Bankai."

"But it's risky."

"If he can't master Bankai during that time, he'll never be able to achieve it."

The Captain-Commander finally spoke. "I may not be fully aware of what you younger ones are involved in."

"But Naruto, you've always been mature and reliable."

"You know this situation best."

"I'll leave the decision of how to handle Kurosaki to you."

With that, he closed his eyes.

Shunsui looked a bit surprised. The old man made a decision like this?

"So, you want to send Ichigo back to the human world?" Naruto asked.

Bankai could be learned in Soul Society, but Yoruichi specifically mentioned mastering Hollow powers, which meant involving Shinji Hirako and the other Vizards. They were still branded as criminals, and the Central 46 hadn't lifted their punishment.

Unable to return to Soul Society, there was only one option left.

Yoruichi nodded.

Naruto lowered his head, thinking for a while before turning to Ichigo. "Can you handle learning Bankai using the Tenshintai?"

"Of course," Ichigo responded without hesitation. "At this point, I'll do whatever it takes."

Naruto continued. "Then that's the plan."

"You'll stay in the Seireitei and train to master Bankai. If you succeed, you'll return to the human world."

"I will personally lead and ensure your safety."

"If you fail to learn Bankai..."

"You'll remain in the Seireitei under our protection. How does that sound?"

This final question wasn't just directed at Ichigo—it was also meant for Yoruichi and the Captain-Commander.

"Let's go with your plan," the Captain-Commander agreed.

Yoruichi also nodded. "I have no objections."

Mayuri raised his hand. "Can I come along?"

Naruto looked at him.

"I'm quite interested in the Tenshintai," Mayuri grinned. "I've read the research notes but never had the chance to see it in action."

"I wouldn't want to miss out on this opportunity."

Naruto nodded, his expression neutral. "Fine."

The meeting concluded.

Initially, Yoruichi intended to take them to her and Urahara's secret base. However, under Mayuri's invitation, they eventually went to the 12th Division's underground training area.

"The facilities here are much more advanced," Mayuri clapped his hands.

The lights flickered on, and various equipment started operating.

The spiritual energy environment was also perfectly calibrated.

Yoruichi looked around, surveying the surroundings. "You've done quite well managing the 12th Division after Urahara's departure."

Mayuri waved his hand, clearly uninterested in discussing the past. "Let's get started, shall we?"

Yoruichi clapped her hands.

A summoning technique activated.

Mayuri clicked his tongue, knowing Naruto had secretly been in contact with Urahara, since they had learned this technique.

A human-shaped doll appeared in Yoruichi's hand.

"This is the Tenshintai. It forces the materialization of your Zanpakutō's spirit."

"However, it's not widely used in the Seireitei because..."

"It only allows the materialization once, with a time limit of three days."

"During those three days, you must defeat the materialized spirit and make it submit to you in order to achieve Bankai."

"Understood, Kurosaki?"

"We can't help you with this."

~~~

Btw, The Keystone can also be called Kāma or Wedge... I'm pretty sure i called it Kāma probably wedge also. But what I saw on reddit they called it keystone. I think we will stick with keystone. I'll be honest with you. I'm lost.