Kisuke and Yoruichi answered Kazuya’s call instantaneously. Yoruichi stretched languidly, yawning. Her voice was sleepy but teasing, “Give me a good reason for disturbing my evening nap.”

Kazuya smiled. “It doesn’t really concern Shihōin-san but Urahara-san. My friend, can I borrow the Hōgyoku?”

Kisuke, usually so quick with a response, was rendered speechless. Kazuya’s request for the Hōgyoku — the most unknown element in the world — was as casual as a friend asking for a book. “What do you need it for?”

The Hōgyoku had only shown one use so far: aiding the survival of the Visored. Even then, it hadn’t fulfilled Kisuke’s original goal to fully rid Shinji and his companions of their Hollow masks.

“I’ll use it to make Apacci and Harribel Arrancars.”

“Huh?” Yoruichi raised her voice in surprise. “Kisuke, Hōgyoku can do that?”

Kisuke shook his head slowly, a gesture not of denial but of uncertainty. “Arrancar and Visored are two sides of the same coin. Theoretically, it’s a possibility.”

Kazuya revealed a soft smile. “Urahara-san, I know things about Hōgyoku that you probably don’t. Give me a chance.”

“I can’t give you the Hogyoku even if I wanted to. It has been put in a deactivated state.”

A spark of surprise flickered across Kazuya's face. Reactivating the Hōgyoku required an immense amount of spiritual energy, twice that of a Captain’s. In canon, Aizen was one of those beings. While Kazuya’s Reiatsu was above Captains, he was far from reaching the requisite level.

‘I should be one and a half of Captain at max.’

Uncertain, he gave a resigned sigh. “I know of a method to activate it.”

Even Kisuke didn’t know the method of awakening the Hōgyoku from its current dormant state. “You know too much, young padawan.”

The idea of handing over the Hōgyoku to a Vasto Lorde Arrancar, let alone someone with past connections to Aizen, unsettled Kisuke. It felt like giving a loaded gun to a mischievous youngster.

“Let me try,” Kazuya insisted. “I won’t disappoint you, Urahara-san.”

Kisuke weighed in his options before finally giving a nod. Kazuya’s support was invaluable in his war against Aizen. Besides, he was curious about Hōgyoku’s mysterious abilities. “I’ll be keeping an eye on you throughout.”

“Sure.”

…

Minutes later, Kisuke returned with the Hōgyoku — an orb glowing with hues of purple and blue sealed in a glass-like, transparent dodecahedron.

Despite its dormant state, Kazuya felt a connection to it, as if he could hear a heartbeat echoing from within its sealed depths.

He wasn't the only one drawn in by this strange phenomenon. The egg, resting in Sung-Sun’s company, twitched to life, emanating waves of powerful Reiatsu that seemed to echo the rhythm of the heartbeat Kazuya sensed. 

‘I definitely have a connection to the Soul King.’

Kisuke's eyes, sharp as ever, caught the subtle nuances of Kazuya's reaction. This strange display solidified his suspicions about Kazuya’s uncanny abilities. “What’s the activation method?”

Kazuya shrugged nonchalantly. “We need someone who has twice the Reiatsu of a Captain.”

A moment of stunned silence followed his statement. Yoruichi’s golden eyes held a question, asking if he was joking. When he merely returned a serious gaze, she let out a sigh. “Where will we find that someone?”

Captains were already the strongest beings the Seireitei had to offer. Only the prestigious Royal Guard might possibly satisfy such an outrageous requirement.

“Haha, Aizen fits the requirement. That guy is a monster.”

Kisuke unsealed the Hōgyoku before tossing the orb at Kazuya and calmly fanning his face. “Let’s see you try.”

Catching the Hōgyoku deftly, Kazuya allowed his Reiryoku to infuse the orb. Its luminescent hues dimmed, replaced by an almost void-like black. However, it wasn't enough. Just as he was about to cease his attempt, a sudden surge of Reiatsu flowed from his Zanpakutō. The egg, as though answering some unseen beckoning, floated towards him and began sharing its Reiatsu, as if co-conspiring to activate the Hōgyoku.

The egg’s Reiatsu easily reached the level of an Adjuchas, a Hollow only second to Vasto Lorde and Captains in terms of Reiatsu.

Kisuke turned to Yoruichi. “Yoruichi-san, what do you think?”

The black cat gracefully hopped on his hat. “I’m genuinely happy he is on our side.”

“Me too.”

Suddenly, the Hōgyoku radiated a chilling aura, shaking everyone present to their core. It was akin to an ancient beast waking from a long slumber. Kisuke never imagined he would encounter this aura again after having sealed the Hōgyoku away. It was unlike Reiatsu or anything comparable, existing in an entirely different dimension.

“Now you know why I sealed this thing.”

“Hmm…” Yoruichi nodded. “We can’t let Aizen get this.”

“Never.”

Meanwhile, an involuntary smile crept onto Kazuya’s face. This success in reviving the Hōgyoku was solely due to the egg’s assistance. Affectionately, he patted the egg before tucking it securely under his arm. “Let’s fucking go, Egg-chan.”

“Egg-chan, the MVP,” Kisuke whispered. “Kazuya-san, finish it quickly. I’ll seal it back after you’re done.”

“Of course,” he confirmed with a nod, hovering the reawakened Hōgyoku over Apacci’s head. “Are you ready?”

She stepped away from him. “Will it stop me from becoming Vasto Lorde?”

The Vasto Lorde Class was her obsession. She wouldn’t hesitate in giving up her Arrancar form if it meant becoming a Vasto Lorde.

“I don’t think so.”

Her eyes hardened with determination. “Then… I'm ready.”

Kazuya filled the Hōgyoku with his Reiatsu and his aspirations. As his energy saturated the orb, its gray hue darkened until it reached the absolute black of a moonless night. Suddenly, it expelled a blinding radiance. This dazzling light enveloped Apacci, and then it splintered, scattering around like countless shards of shattered glass.

“Kazuya!”

A figure dashed through the swirling shards. It was Apacci, her form fully nude. Throwing her arms around him, she pressed against him, her form softer and more voluptuous than he remembered. In his memory, she leaned towards a slender silhouette, yet now, she seemed to mirror Mila Rose’s curvaceous form, in both her figure and height.

‘She is like 5’5”. Almost four inches above her canon height.’

She perhaps changed her desired body after seeing him gush over Mila Rose, resulting in her attaining a more curvaceous form.

‘This jealous little.’

Blushing, Apacci gazed up at him, her heterochromatic eyes looking deeply at him. Her eyebrows furrowed in a futile attempt to disguise her embarrassment. “I’m an Arrancar now.”

He gave a gentle nod. “I can see that.”

“Next step is to become a Vasto Lorde, then I’ll work towards my promise of becoming the strongest Arrancar.”

She still remembered her vow from the days they wandered the Hueco Mundo by themselves. A vow he made her do for fun but she took it seriously. Still, he felt there was more to her hunger than their promise.

‘She wants to protect me, doesn’t she? How cute.’

He placed his hands around her hips, and her blush deepened. “You’ll have to surpass me if you want to be the strongest Arrancar.”

“Why are you counting yourself? I’m talking about Hollows and Arrancars. You’re an abomination of Hollow and Quincy.”

“Hey, that one hurt.”

“I was joking…” She lowered her gaze and nuzzled her face against his chest. “I just have to surpass Harribel who is the second strongest Hollow right now.”

“Good luck,” he replied and encouragingly patted her back. "You can do it."

Apacci clenched her teeth, well aware that Harribel's power would receive a massive boost after her own transformation into an Arrancar. “Everyone in Hueco Mundo once believed that the formidable Baraggan they worshiped was invincible. You proved them wrong. I'll do the same."

Her determination ignited a surge in her Reiatsu, startling everyone around.

***

Here is Apacci’s new form for reference.