Laid-back Highschooler In Bleach (With Soul Cube)

A collective gasp spread through the room, drowning in the tension that was already palpable. Bankai was not just a technique; it was an extension of their very soul.

"So, we'll lose our most powerful weapon?" Hitsugaya's icy voice broke the silence. "That's a critical disadvantage."

Kai shrugged. "Oh, it's worse than that, but that's for later."

A chill ran through the room again. Kai had divulged shocking truths, but what really unnerved everyone was his casual demeanor. It was as if he was discussing the weather.

"So, what's the last piece?" Byakuya asked, trying to sound unphased but failing to hide a tinge of anxiety in his voice.

Kai grinned, the expression out of place in the thick atmosphere. "The real kicker is this: You won't win unless Yamamoto kicks the bucket."

Silence. Complete, heavy silence. Eyes turned to Yamamoto, who seemed to age a decade in that moment.

"Explain. Now." Ukitake's voice was tinged with a desperation no one had ever heard before.

Kai's playful demeanor vanished, replaced by a gravity that commanded attention. "Are you dense, or just playing the part, Ukitake?"

Everyone in the room felt the sudden shift in mood. Eyes turned to Kai, their gazes tinged with a newfound apprehension.

"Yhwach's ultimate target isn't Soul Society or even you all—it's Yamamoto," Kai elaborated. "His Bankai is unparalleled, something none of you have a prayer against. Now, what do you think will happen if that power falls into enemy hands?"

Shunsui Kyōraku furrowed his brow. "Are you saying Yhwach can steal his Bankai? How can you be sure?"

Kai glanced at Yamamoto, who seemed to carry the weight of a thousand years in his eyes. "Do you think you can prevent it?"

Yamamoto shook his head slowly, admitting a bitter truth he never wished to face.

"That settles it. Yamamoto will die—that's an irrefutable fact," Kai said, every word deliberate, each syllable a nail in a coffin. "The question is how. Either he dies fighting Yhwach, thereby handing him unimaginable power, or..." Kai paused, letting the implication hang in the air like a dark cloud, "...or we kill him ourselves. Deny the enemy what they most desire."

The room fell into a disquieting hush, each Shinigami wrestling with Kai's terrible logic. Unohana's eyes widened, Zaraki’s grin vanished, and Hitsugaya looked as though he'd been slapped by a glacier.

"And to answer your question, Ukitake—the reason I called you dense is that, when Yamamoto dies, they will descend from their lofty perch."

Everyone looked perplexed while some understood. Hitsugaya broke the ice, his eyes narrowed, "They?"

Kai pointed skyward. "Division 0, Royal Guards," he stated matter-of-factly. Recognition dawned on the faces of the older captains. Hiyori, surprisingly, was among those who understood. Her old captain had been promoted to the Royal Guard, after all.

Ukitake seemed to age another ten years, a pale understanding settling on his face. He no longer had words.

Ichigo, his voice tinged with desperation, pressed on, "Kai, is there no other way?"

Kai shook his head, his gaze heavy with finality. "Royal Guards will not descend if the old man is alive. And some of you need them. The Wandenreich Medallion only works if you and the enemy have similar power levels and if they understand your Bankai. You've got a few days before their army is at your doorstep. Train. Evolve your powers. Or take the easy way out. But don't let the enemy steal your Bankai."

The room went from ice-cold tension to a near vacuum of speechlessness. Kai shifted his eyes to Yamamoto. "Do you need to say goodbye?"

Yamamoto's reply was a gruff scoff. "Who do you think I am?"

A wry smile crossed Kai's lips. "Whatever." With a wave of his hand, Yamamoto disappeared in an instant, leaving the room in a state of bewildered shock. Their revered Captain... gone, just like that?

Kai turned his attention to Kyoraku. "You're the Commander Captain now."

Then, swinging his gaze around to the rest, he announced, "Ichigo, you stay with them. Kenpachis—both of you—and Shinji, come with me."

With that, he summoned a portal to a mirror dimension and stepped through with Shinji behind him. Zaraki and Unohana exchanged a glance, then followed, Yachiru scampering in behind them. The portal vanished, leaving the remaining Shinigami staring at the empty space where their leaders had stood.

As the reality sank in, eyes met in silent conversation, each grappling with Kai's brutal logic. Hitsugaya clenched his fists, his eyes pools of icy determination. Byakuya's hand twitched toward his Zanpakutō, and even Shunsui couldn’t muster his usual smile. Ukitake looked as though the weight of their reality had physically pressed upon him.

Unspoken but understood, their fates rested in their own hands, or rather, in the powers they must rapidly evolve. And as for the Royal Guard, that enigmatic last resort, everyone understood: their descent was the doomsday clock ticking down to zero.

Kai's ominous prophecy echoed in their minds: train, evolve, or be your own undoing. And as the room emptied, dispersing to make those few days count, one thing was clear: Kai had set them on a path of unavoidable confrontation, and the choices ahead would determine not just the fate of the Shinigami, but of the worlds they were sworn to protect.

In the Mirror Dimension, Kai appeared in the middle of a Utopic world. A vast, grassy plain stretched as far as the eye could see, interspersed with tranquil trees and a soft, meandering river. It was as if someone had taken the ideal of peace and given it physical form. The sky above was almost ethereal, its few fluffy clouds seemingly suspended in an eternal waltz. A colossal tree stood at the center, its leaves rustling gently in the wind.

"Ah, back to my sanct—" Kai began, but his words were interrupted when a jubilant female form leapt onto his back.

"Kai! Where were you? You said you would come back in seconds but it has been minutes!" Hikari bit his cheek, her golden locks cascading around them both.

Kai sighed. "Hikari, we have guests."