Ōko Yushima  

"I've reviewed the Twelfth Division's experiment records. At the time, a researcher named Ōko Yushima, building upon the foundation of 'Temporary Souls,' developed a new type of artificial soul, the 'Mod Soul.'"

Even Urahara, known for his vast knowledge and scientific prowess, couldn't help but express admiration for this Ōko Yushima fellow.

"Temporary Souls" were simply that - temporary. Artificial souls with an ephemeral existence. If they weren't utilized within their short lifespan, they would dissipate and returned to their basic spiritual particles.

"Mod Souls," however, were different. They were designed to exist indefinitely, indistinguishable from genuine souls. As long as these "Mod Souls" were encapsulated within "Soul Candy" pills, their existence would be preserved indefinitely.

After creating the "Mod Soul," Ōko Yushima had submitted a research proposal to the Seireitei: The Soul Soldier Project!

The essence of this "Soul Soldier Project" was to use the spiritual pressure of the Seireitei's powerful captains as the base material for "Mod Souls," crafting artificial souls imbued with the captains' memories. Then, using the captains' spiritual pressure once more, he would create corresponding "Gikon," artificial bodies, to house these Mod Souls.

When a matching "Mod Soul" was implanted within its corresponding "Gikon," the result would be a superweapon possessing the captain's memories and abilities.

Undeniably, if this research had been approved, the Seireitei's strength would have doubled overnight.

However, this very potential had led to its rejection by the Central 46.

While the "Soul Soldier Project" could significantly enhance the Gotei 13's capabilities, it also presented a hidden danger: If these "Soul Soldiers," possessing the memories and power of captains, were to rebel against the Seireitei or secretly replace certain captains, how could anyone differentiate them from the originals?

Thus, the Central 46 not only rejected Ōko Yushima's proposal but declared "Mod Soul" research forbidden. They even attempted to apprehend Ōko Yushima.

However, when they arrived at the Twelfth Division, Ōko Yushima was nowhere to be found. They could only seal away all research equipment and data related to "Mod Souls."

Tessai Tsukabishi, listening to Urahara's explanation, remained impassive. To him, "Temporary Souls" and "Mod Souls" held no significance.

Ever since he had been condemned by the Central 46 for using forbidden Kidō and subsequently rescued by Yoruichi Shihōin, Tessai had made a decision: He would spend the rest of his life as an assistant to Urahara and Yoruichi, following their commands without question.

He agreed with Urahara's actions. When Shinji Hirako and the others had been used as subjects in Aizen's Hollowfication experiments, the Central 46 had wanted to eliminate them. Urahara, however, had chosen to expose his own research on Hollowfication, saving them. Yoruichi, in turn, had risked being branded a traitor by rescuing both Urahara and Tessai from the Seireitei.

Their actions resonated with Tessai's own beliefs. After all, he, too, had used forbidden Kidō to protect his subordinates and those who had been Hollowfied.

Urahara knew Tessai wouldn't be interested in the details of "Mod Souls."

But some things needed to be said, regardless of whether others cared.

Loyalty deserved to be acknowledged.

While Tessai had assumed a role akin to a housekeeper, Urahara never treated him as such. In fact, Urahara, a man burdened by the weight of his own actions, deeply admired Tessai's unwavering sense of justice.

Decades ago, when Shinji Hirako and the others had been subjected to Aizen's Hollowfication experiments, it was Tessai's decision to use forbidden Kidō that had given Urahara the courage to expose his own research and save them.

"So, Urahara, you suspect these Gikon are connected to the missing Ōko Yushima?" Yoruichi, having transformed back into her human form, asked.

"I don't know for sure, but it's highly likely," Urahara frowned as he watched the Gikon of Isshin Shiba begin to dissolve into spiritual particles.

"To think there's someone lurking in the Seireitei, hidden even deeper than Aizen… If they hadn't come looking for us, we would never have suspected that this forbidden experiment was still ongoing. And it seems they've achieved considerable progress. Judging by the strength this Gikon displayed, it was no weaker than the real Captain Shiba."

"According to him, they were alerted when Yoruichi entered the Dangai. To eliminate any potential threats, they want to eliminate her and anyone who can open portals into the Dangai. That suggests this individual is likely hiding within the Dangai. Even if they're not physically present, there must be something there that's crucial to their plans. That's why they're monitoring anyone who can enter the Dangai to prevent their secrets from being exposed."

"So, Urahara, should we investigate the Dangai?" Yoruichi asked.

"It's pointless," Urahara sighed while shaking his head.

"We're still wanted criminals. If we appear in the Dangai, whoever's monitoring it can easily expose us to the Seireitei. They'll send several powerful captains to expel us, to prevent us from causing any trouble. And who knows how many of the Gotei 13 captains are genuine, and how many have been replaced by Gikon?"

Yoruichi fell silent. He was right. There was no guarantee that all the Gotei 13 captains were the originals.

However, the good news was that, based on the Gikon's actions, this hidden researcher, this Ōko Yushima fellow, seemed to be operating independently of Aizen.

After extinguishing the flames engulfing the shop and ensuring no one would be drawn to the scene, Tessai dispelled his barrier.

But the moment he did, the three of them were drawn to another part of Karakura Town. A faint barrier emanated from an abandoned warehouse, but its primary purpose seemed to be preventing ordinary humans from entering.

"Ailin's" spiritual pressure, clashing with the Visored within, was easily detected by Urahara, Yoruichi, and Tessai.

"This is bad! It's Aizen's spiritual pressure!"

"The Visored are in danger!"

"Yoruichi, Tessai, we have to go!"

"Right!"

Without time to clean up the remnants of their battle with the Gikon, the three of them vanished in flashes of Shunpo and began rushing towards the abandoned warehouse.

…

Boom!

Hiyori Sarugaki was struck down into the ground and created a deep crater. Her Hollow mask shattered which rendered her unable to fight.

"Hiyori!" Mashiro Kuna, seeing Hiyori's defeat from her vantage point in the air, transformed into a stream of light as she launched a kick towards "Ailin."

"Mashiro Kuna, Super Super Flying Kick!"

A huge spiritual pressure exploded from her body and a wave of intense heat burst forth from her right leg.

"Bakudō #63 - Sajō Sabaku!"

With a murmur, "Ailin" unleashed several chains of yellow reiatsu to bind Mashiro. They dragged her towards him. Her speed rapidly decreased until she came to a standstill right before him.

Perhaps it was her vulnerable position, but without hesitation, "Ailin" backhanded her across the face.

Boom!

Boom!

The first sonic boom was the sound of Mashiro being struck. The second was her body slamming into the ground.

With Mashiro's defeat, the Visored had lost their second member.

"Mashiro!"

Witnessing Mashiro's injury, Kensei Muguruma charging towards "Ailin."

"So predictable."

"Ailin" shook his head. Previously, there had been some semblance of strategy in Kensei's attacks. But now, consumed by rage, he was simply lashing out.

Swoosh!

After dodging another strike, "Ailin" casually swung his Zanpakutō.

Shhh!

A spray of blood erupted from Kensei's body as he collapsed to the ground.

"Kensei!"

Shinji Hirako and the others were horrified at their comrade's defeat.

Love Aikawa leaped into the air as flames engulfed his Zanpakutō, Tengumaru, transforming it into a blazing inferno.

"Fire-Breathing Warhammer!"

Boom!

A massive fireball descended while radiating waves of intense heat.

However, facing Love Aikawa's power, "Ailin" merely raised his left hand.

"Hadō #91 - Hyōga Seiran!"

A wave of chilling energy erupted from his palm and wherever the cold air passed, it was frozen into ice. It transformed into a towering glacier that collided with the descending fireball.

Boom!

The clash of fire and ice generated a deafening roar and a thick cloud of steam. The heat melted the ice, but the chilling energy refroze the moisture, fueling the glacier's growth.

When the steam finally cleared, Shinji and the others saw Love Aikawa and his "Fire-Breathing Warhammer" encased in ice.

Crack! Crack!

Moments later, the glacier shattered. Countless bloody shards of ice came raining down. The wounded Love Aikawa's Zanpakutō reverted to its sealed state and fell from the sky alongside the broken ice.