The greatest challenge in Hollowfying a Captain-level Shinigami lies in one immutable truth—their spiritual pressure is simply too overwhelming. Unless they actively surrender, fully opening themselves to the Hollowfication process, it's nearly impossible to push the hollow essence into the core of their soul.
So when Aizen witnessed the subdued reaction from Ōtoribashi Rōjirō after the slaughter of his subordinates, he made a ruthless choice—he killed Iba Chikane.
As expected, Rōjirō snapped.
Enraged. Consumed.
And that's all Aizen needed.
Within two minutes, Rōjirō was on his knees, body pierced, reason unraveling as the inner beast clawed out through the cracks of his soul. His final moment of lucidity was filled with confusion.
How had Aizen become so powerful, so fast?
That oppressive reiatsu—it had made him feel as though he were standing before the Captain-Commander himself.
In that final flicker of sanity, Rōjirō recalled the Kōrōdani Rebellion five years prior.
Was it Aizen who had killed his former Captain, Kamikawa Ren'nosuke?
"Forgive me... Captain. Big Sis Chikane..."
He whispered the apology as his mind was drowned in hollow instinct.
Back in Seireitei, the complete radio silence from Rōjirō's squad finally alarmed Yamamoto Genryūsai Shigekuni.
A Captain's Meeting was urgently convened.
Orders were clear and swift: assemble an elite investigation team to head to the location where Rōjirō's squad vanished. Deploy additional squads—each with at least one Captain and Vice-Captain—to other parts of Rukongai to quell the rising chaos.
Seireitei's defense was left to:
The 1st Division under Yamamoto
The 2nd Division under Shihōin Yoruichi
The 11th Division under Zaraki Kenpachi
Why Yoruichi and Zaraki specifically? Because:
Kenpachi gets lost. Yamamoto figured if he sent him out, the crisis might end before Zaraki even found the battlefield.
Higashi Shuuichi, Kenpachi's Vice-Captain, was too dangerous to let wander free. He needed to stay under close watch, possibly unsealed by Yoruichi if an emergency arose.
Other divisions had various captains and lieutenants missing due to previous assignments. So Yamamoto dispatched:
Kyōraku Shunsui (alone) to West Rukongai
Aikawa Love and Kotsubaki Jirōemon to North
Urahara Kisuke and Grand Kidō Chief Takezō Hōrinmaru to South
Hirako Shinji, Muguruma Kensei, Kuna Mashiro, Yadōmaru Lisa, and Assistant Kidō Chief Hachigen Ushōda to the East, where Rōjirō had vanished
The 6th Division, being tied to the Kuchiki noble house, was not deployed. With the nobility still recovering from the Kōrōdani Rebellion, it was deemed too risky to expose them again. Kuchiki Ginrei, the current head of the clan, chose to remain and protect the aristocratic districts.
As squads deployed, Kyōraku looked at Lisa, hesitating to ask her to stay. She was technically his Vice-Captain, but Vice-Captains were flexible in deployment. Still, Lisa left with Shinji without him saying a word.
"With Shinji and Kensei, they'll be fine... right?"
That was all he could whisper.
He had no idea how wrong he was.
Within an hour, the Eastern unit—the strongest squad assembled—was obliterated.
Even Sarugaki Hiyori, whom Urahara had sent as support, was lost.
As chaos erupted and Shinji and the others began Hollowfying, he could barely speak. Rage trembled through every syllable.
"Aizen Sōsuke! I knew you were never what you seemed!"
Aizen stood calmly, smiling with open arms.
"So what if you knew? Could you change anything?"
"All you ever do is doubt, never act. What makes you any different from the weak you mock?"
"I doubted someone too once. A man of immense wisdom, whose strength lay in silence. But I—unlike you—gave him a stage. He gave me miracles in return."
"That's our difference, Captain Hirako~"
Emotion overwhelmed Shinji. The Hollow within him devoured what reason he had left.
And in that moment, he regretted not sending Aizen to the Maggot's Nest when he'd had the chance.
But it was too late.
Three Captains were in the throes of Hollowfication. Their unstable spiritual pressure tore through the atmosphere like a storm. Aizen canceled his suppression field, allowing their violent reiatsu to ring across all of Seireitei.
Urahara, fresh from handling the southern crisis, immediately noticed.
"Hōrinmaru. I'll need your help."
Without hesitation, he turned to the Grand Kidō Chief.
He had requested Hōrinmaru's participation precisely for this contingency—to stop the situation from spiraling further.
He had not expected Shinji's elite squad to fall so quickly.
But he wasn't the only one caught off guard.
North Rukongai: Love Aikawa had barely left Seireitei when his own Vice-Captain, Kotsubaki Jirōemon, betrayed him.
Or rather, it was Tōsen Kaname.
"What the hell do you want?!"
Love roared, unable to fight back effectively under the weight of betrayal and the sudden Hollowfication process.
Tōsen answered with quiet resolve.
"To cleanse this filthy world. To create a better one."
His dream had never changed.
Killing a few nobles wouldn't change anything.
He needed to burn the pillars of the old world and lay the foundation anew.
That was the truth Aizen had shown him—and the one he had sworn to follow.
"Still feeding me that nonsense?!"
Love couldn't understand him. In truth, almost no one in Soul Society could.
But Aizen could. And that was all Tōsen needed.
While Captains and Lieutenants fell to chaos, the battle between Gin Ichimaru and Higashi Shuuichi entered its second phase.
Tōsen, knowing this, abandoned Love mid-Hollowfication and flash-stepped toward Gin's location.
And Aizen?
He remained, watching the Hollowfied Captains tear into their surroundings—until he sensed the presence he'd been waiting for.
Urahara Kisuke.
Captain of the 12th. Founder of the SRDI. Creator—and current holder—of one of the Hōgyoku fragments.
He lay in wait, cloaked in darkness, watching.
And when Kisuke pulled out the Hōgyoku…
No—when he didn't, Aizen frowned.
He didn't even use it... but the Hollowfication stopped?
Only when he saw Hōrinmaru weakened, did Aizen realize the truth.
Time Suspension…
A forbidden spell. One of the absolute taboos of Soul Society. Buried even within the archives of the Grand Spirit Library.
Only the highest tier of personnel could even access it.
Aizen had never taken Hōrinmaru seriously.
Now he understood why Kisuke had brought him.
His thoughts were interrupted by an overwhelming blast of spiritual light.
"Hadō #91: Senju Kōten Taihō."
Kisuke barely smirked, muttering:
"Finally got you."
The beam surged—only to miss its target.
And Aizen, suddenly aware of pain in his shoulder, looked down.
Pierced. Numb.
When...?
Even with Hōrinmaru's teleportation, he should've sensed it. He should've had time.
But the truth? He'd been fooled.
The Kisuke that stood in Hōrinmaru's protection was a decoy.
A synthetic body made with gigai.
The real Kisuke had cloaked himself, used the Hōgyoku to stabilize the Captains, and waited in ambush.
Strike. Conceal. Strike again.
"Cry, Benihime! Razor."
His Zanpakutō released, crimson reiatsu scything forward.
Aizen's smile faded into faint disappointment.
"Such a clever trap… and such a weak follow-up."
Though paralyzed, he danced around Benihime's arc—appearing before Kisuke in a flash.
"Bakudō #75: Gochūtekkan!"
Five iron pillars descended—forcing Aizen back.
"I remember you now, Aizen Sōsuke—Vice-Captain of the 5th."
Kisuke finally recognized the mastermind.
"So it was you. The Kōrōdani Rebellion... the Hollowfication... all of it was you."
He wasn't afraid. Aizen's reiatsu was overwhelming, but not invincible—not yet.
"And if I said it wasn't?"
Aizen chuckled.
He knew the battle was slipping away. He wouldn't press further—not with Hōrinmaru still looming.
"Speak your true goal, Aizen. There's no escape now."
"Is that so?"
Aizen smiled, turned, and walked away.
Hōrinmaru cast three high-level binding spells—but not one touched him.
"Let it go, Hōrinmaru."
Kisuke held him back.
Something was off. The whole encounter had been too easy.
Aizen's confidence… his smile…
Was it all just bait?
What did he stand to gain from Hollowfying Captains?
And what came next?
As Kisuke pondered, new spiritual pressure exploded from North Rukongai.
Love Aikawa—gone.
More chaos. More pieces lost.
And one thing became terrifyingly clear—
Aizen was not alone.
"Hōrinmaru!"
"Already on it!"
Without needing to speak further, Kisuke and Hōrinmaru vanished—teleporting to the next battlefield.
And in the only fight still underway...
Tōsen Kaname had just entered the fray.