This was a special unit belonging to the Onmitsukido, under the jurisdiction of the Second Division, specifically responsible for guarding this great prison.
Kisuke Urahara had once been the commander of the Kanritei.
"Halt!"
One of the Kanritei members shouted sternly, his Zanpakuto already drawn half an inch from its sheath. "Who goes there?!"
"Captain of the Ninth Division," Kaname Tosen's voice was calm and unwavering. "Kaname Tosen."
"This is an absolute restricted area! Do you have a warrant?"
"Even a Soul Reaper Captain is not allowed to take a single step closer without the dual approval of the Head Captain and Central 46!"
Tosen did not speak, simply pulling a scroll from his robes in silence.
It was a special investigation warrant stamped with the highest-level seal of Central 46, a document that could not be issued without a unanimous vote.
"The upper echelons are currently in turmoil due to the Ryoka invasion. Central 46 has determined that the Ryoka's actions are connected to a prisoner within. I have been granted special permission to enter Muken and extract the relevant intelligence."
The two guards exchanged a glance and suspiciously took the scroll.
In their eyes, the seal on the scroll was as crimson as blood, exuding absolute authority through the flow of its Reiryoku.
Every stroke of the characters and every line of the pattern proved beyond a doubt that this was an order from the highest governing body.
Of course, this was merely an illusion.
The true Central 46, that group of decaying old men, had already become dead souls under Sosuke Aizen's blade.
Even the one issuing orders in the name of Central 46 these past few days was Aizen himself.
"It is indeed... a supreme special warrant."
The guard's hands trembled slightly as he returned the scroll to Tosen. "It's just... is there no approval from Head Captain Yamamoto...?"
"The situation is urgent. Head Captain Yamamoto has already gone to intercept the Ryoka."
Tosen frowned, his tone turning severe. "What? Is an order from Central 46 not enough to let me inside to ask a few questions?"
"O-Of course not!"
The guard was merely a subordinate doing his job; naturally, he didn't dare question the noble core.
His tone became respectful and fearful as he stepped aside. "In that case, please enter!"
"But please be extremely careful. The monsters in Muken... even sealed, they possess terrifying power."
"Thank you for the warning."
Tosen put away the scroll. Amidst the rumbling sound of the guards working together to undo the complex seals, he stepped through the slowly opening giant black iron doors.
Behind the doors lay a zone of dead silence that devoured all light and sound.
This was a space of absolute darkness with no up, down, left, or right, and no gravity... It felt as if even the darkness itself was being swallowed.
This was Muken.
A void space existing solely to bury all sins.
Tosen walked into this nothingness. The giant doors slammed shut behind him, completely cutting off the last trace of the outside world.
But he did not lose his sense of direction, simply continuing forward along the path.
After walking for about a few hundred paces, he encountered a sturdy Sekkiseki fence.
He knew he had arrived.
"The weather is quite nice today."
Tosen stopped in his tracks and offered a completely half-hearted greeting to the darkness before him.
"I know you are watching me. Or rather, from the moment I stepped into the Muken prison, you have been watching me."
There was no response from the darkness.
But the flow of the air changed.
The originally stagnant air began to slowly swirl, and countless microscopic Reishi gathered and wove together in front of Tosen.
This scene was highly unusual. One must know that this entire area was paved with Sekkiseki and special seals; prisoners shouldn't be able to mobilize any Spiritual Pressure fluctuations at all.
A moment later.
A man dressed in white noble attire with long black hair appeared before Tosen, emerging as if from lightless black water. His features were so delicate and handsome that they carried a sickly pallor.
He was not bound by chains or a straitjacket.
Because for this man, as long as he wished it, no chains could ever hold him.
He remained here voluntarily, solely to atone through this endless solitude and to use this deep, dark cell to restrict his own uncontrollable power...
The Eighth Kenpachi, Kenpachi Azashiro.
His true name, Soya Azashiro.
"Captain of the Ninth Division, Kaname Tosen."
Soya Azashiro's voice was cold and elegant, carrying a sense of detachment.
He tilted his head slightly, sizing Tosen up. "What a rare guest... Aside from the Kanritei, you are the first visitor to step foot in here."
Tosen was not surprised that the other party knew his name.
According to Aizen, Soya Azashiro was once one of the Seireitei's greatest troubles.
Through certain encounters, Aizen had learned of the ability of his Zanpakuto, Uro Zakuro, which allowed him to merge his own Reishi with any substance.
Aizen speculated that, as long as he willed it, Azashiro could merge with the Reishi, the earth, and even the air of the entire Seireitei.
Even while residing in this sunless Muken, he knew everything about the outside world like the back of his hand.
In a sense, he was the strongest intelligence network in the world, and the most unsolvable observer.
"Since you know everything happening on the outside, I will skip the pointless pleasantries."
Tosen cut straight to the chase. "Soya Azashiro, on behalf of Lord Aizen, I invite you to join us."
"Join you?"
As if hearing an amusing joke, the corners of Soya Azashiro's indifferent mouth curled up. "To rebel alongside you, or to conduct those slightly excessive little experiments?"
"It is not a rebellion, but a revolution," Tosen corrected him.
"You and I both know the corruption of this world... The nobles occupy their seats while doing nothing, Central 46 is stuck in their old ways, and the Soul Reapers indulge in a fake hierarchical society..."
"This world needs a cleansing. It needs someone who truly possesses justice and power to reshape its order."
"Justice..."
Soya Azashiro savored the word, the mockery in his eyes growing thicker. "For the sake of this so-called justice, you would use your comrades in the Tenth Division as discarded pawns, leaving them to break down as they slaughter each other?"
"I want you and Aizen to get one thing straight. I never said I wanted to betray the Soul Society; it's just that my plans were a bit radical."
"Even if our ideals clash, it doesn't mean I would kill my comrades. You've got the wrong person."
These words were not false.
The reason Soya Azashiro exiled himself to Muken was simply because his plan to modify the souls of Rukongai residents, turning them into [Weapons to Attack Hueco Mundo], was vetoed by the will of the Soul King.
Coupled with the fact that Uro Zakuro's abilities had caused a large number of innocent Soul Reaper casualties, he truly felt guilty in his heart, which led him to make this decision.
"Furthermore, Captain Tosen."
Soya Azashiro shifted the topic, his gaze turning sharp. "I refuse, not only because I disapprove of your honorless and cruel methods, but also because—"
"You have no chance of winning."
He raised his hand, his fingertips lightly tracing through the empty air, as if outlining the silhouette of the entire Seireitei.
"Aizen is indeed very strong, and his Kyoka Suigetsu is quite formidable."
"However, you aren't just facing a few Captains with Second and Third-class Spiritual Power..."
With deep apprehension, Soya Azashiro uttered this name:
"Genryusai Shigekuni Yamamoto."
"All conspiracies are nothing but fragile glass in the face of his absolute power. He alone is enough to dismantle all your plans."
"Not to mention, above the heavens, there is still Squad Zero..."
Soya Azashiro shook his head, seemingly intending to end this conversation.
"Hundreds of years ago, I too tried to change this world, but I failed. I lost to that insurmountable barrier."
"No matter what you have planned, it will ultimately end up as nothing more than a farce."
"I have no interest in accompanying you to your deaths. Please leave."