Laid-back Highschooler In Bleach (With Soul Cube)

As he invoked his Bankai, the Zanpakuto morphed. The staff extended its size, towering over him. The orb at the top transformed into a mirror-like surface, reflecting the fear on the faces of the unconscious civilians, the towering Arrancar, and the silent desperation on Kai's own face.

He turned to the Arrancar. Number 10 was towering over him, his smile stretched across his face, filled with malicious glee. Kai, despite his laid-back demeanor, was filled with an undercurrent of anger. The Arrancar's nonchalance towards the unconscious people, towards the potential soul harvesting, it was all too revolting for him.

"And what are you going to do, little shinigami?" Number 10 taunted, his voice echoing with a sickening delight. He made a sweeping gesture around the park, indicating the fallen civilians, their unconscious faces devoid of any understanding of the danger they were in.

Kai, without a word, swung his staff towards the Arrancar, the mirror-like surface facing him. The reflection of Number 10 was distorted in the mirror's surface, his malicious smile turned into a grotesque smirk. Then, with a low growl, the Arrancar lunged at Kai, his clawed hand swiping in a wide arc.

As the attack connected with the mirror's surface, a brilliant flash of light erupted from it. The reflected attack was thrown back at the Arrancar, striking him squarely in the chest. The force of his own attack threw him back, and he crashed onto the ground with a grunt.

The park was filled with an echo of shocked silence as Number 10 struggled to rise. Ulquiorra, meanwhile, stared at the scene with widened eyes, clearly not expecting Kai to possess such a formidable Bankai.

The smile on Number 10's face was replaced with a look of disbelief and shock. His disbelief turned into anger, and he was up on his feet in a flash. His spiritual energy spiked again, and he launched another attack at Kai, this time a Cero.

But Kai was ready. With a calm that contradicted the situation, he manipulated his mirror to reflect the Cero back at Number 10. The speed was higher this time, catching the Arrancar off-guard. The Cero struck him, and with a shout, he was thrown back again, his form disappearing in the resulting explosion.

Ulquiorra watched in silent disbelief as his comrade was struck by his own attack again. He glanced at Kai, realizing the shinigami was a far more formidable opponent than he'd initially perceived.

Kai stood steadfast, his mirrored staff catching the sunlight, casting kaleidoscopic reflections onto the nearby trees. His brow furrowed as he watched Yami, or Number 10, rise from the wreckage, a dangerous glint in his eyes. Despite the constant taunting, Kai’s demeanor remained nonchalant, his lips curving into a slight smirk.

"You're relentless, aren't you?" He mused, his voice echoing in the silent park. His fingers tightened around his staff as he continued, "Ever thought of just...giving up? It's a lot easier."

Yami glared at Kai, the anger in his eyes palpable. "Don't mock me, shinigami!" He roared, surges of spiritual energy rippling from his form. With a growl, he rushed at Kai, his fists engulfed in a fiery aura of energy. A Bala.

Kai’s smirk never wavered. As Yami’s fist drew closer, he swung his staff in a sweeping motion, the mirror's surface facing the incoming Bala. There was a brilliant flash of light as the Bala made contact with the mirror, and a resounding 'boom' as the energy was hurled back at Yami. The Arrancar was thrown back once again, a look of shock etched onto his face.

The aftermath left Yami seething with rage. Each fit of anger made him grow larger, his hulking form looming menacingly over Kai. Yami let out a low growl, his fists clenching in anticipation.

"You can reflect my attacks all you want," Yami spat, his voice echoing through the park, "I'll just break that shiny toy of yours."

Kai sighed, "Such a hassle." The anger flaring off Yami was undeniable. He slipped a hand into his pocket, pulling out a small, decorated mask. It was his Hollow mask, a symbol of his Visored abilities.

Sliding it over his face, Kai felt the surge of his inner Hollow’s power. A spiritual pressure that far exceeded his own. His eyes glowed a menacing gold from beneath the mask. "You've gone and done it now," Kai said, his voice carrying an unnatural echo.

Yami, blinded by his rage, charged at Kai again, his fist aimed straight at Kai's midsection. However, Kai sidestepped the attack with ease, his movements more agile thanks to the power of his Hollow mask. His grip on his staff tightened, and he struck Yami with it. The Arrancar was caught off guard and stumbled back, grunting in annoyance.

A moment of silence hung over the park as Yami struggled to regain his footing. He glared at Kai, his eyes filled with a wild rage. "This is far from over, shinigami," he roared, charging towards Kai again.

Kai sighed again, meeting Yami's rage-filled eyes. "I'm starting to get tired of your rants," he said, his tone laced with an underlying sense of irritation. With a flick of his staff, he met Yami's charging form, the reflection on his staff capturing the Arrancar's enraged figure.

A resonating crack echoed through the park as Yami's body connected with the staff. His form was thrown back again, his roar of frustration echoing in the quiet. But as Kai watched him get up, the smirk on his face widened.

With a swift movement, Kai raised his hand, pointing it at Yami. His eyes, glowing ominously from beneath his mask, stared at the Arrancar with an unspoken challenge. The next moment, a beam of energy erupted from his finger, a Cero.

The Cero struck Yami square in the chest, throwing him back with a thunderous crash. The force was enough to tear up the grass under him and send a cloud of dust into the air.

Kai kept his hand raised, the remnant glow of the Cero casting long, eerie shadows. Yami emerged from the cloud of dust, visibly larger and more furious than before.

"This isn't fun anymore," Kai mumbled, his shoulders slumping slightly. He tightened his grip on the staff, his gaze fixed on Yami. "Gen'ei Yōhō, Mugon no Yūjin: Zettai Yūjin."