Kaname Tōsen seemed to hear her gentle voice once again.
Across the span of centuries, it soothed the restlessness stirring in his heart.
Was it because everything was about to end?
Was that why so many memories from the past were surfacing now?
No... that was not it.
When a spirit faces a life-or-death crisis, the mind instinctively searches through old memories, desperately trying to find a way to save itself.
A sharp blade pressure closed in with a shrill, tearing howl. Kaname Tōsen finally snapped out of his long reverie and raised the hand gripping his Zanpakutō.
His wrist suddenly sank downward.
A viscous liquid splashed across Kaname Tōsen's body as the blade pressure tore through his Shihakushō.
Pitch-black spirit ink corroded his body, releasing thick black smoke. Muten Natsu's cold eyes widened as he raised Myōki high above his head with his left hand, the blade devouring the drifting black smoke.
Slash.
Myōki cleaved through Kaname Tōsen's Zanpakutō, the inner curve of the blade biting deep into his shoulder.
Kaname Tōsen grabbed the blade of Myōki with his hand, stopping it from cutting deeper.
So fast...
Kaname Tōsen had known about Muten Natsu's draw technique for a long time, yet he had never truly taken it seriously.
Its power was immense, but it came with many restrictions.
A long charging time, no interruptions allowed, limited attack range, and a considerable period of weakness after use.
But once all conditions were met and the charge was complete, the destructive force of the draw technique was enough to drive anyone into despair.
The moment Kaname Tōsen arrived at Sōkyoku using Sentan Hakuja, he ran straight into Muten Natsu's fully charged draw strike.
His captain-class strength and battle experience had no chance to show themselves. In a single exchange, Kaname Tōsen was already gravely wounded.
Or rather, it was precisely because he possessed captain-class strength and extensive combat experience that Kaname Tōsen managed to survive at all.
"Cry... Suzumushi."
Kaname Tōsen spat out blood. The broken blade lying on the ground trembled, releasing strange sound waves that instantly stiffened Muten Natsu's body.
Taking advantage of the moment, Kaname Tōsen broke free from Myōki and flashed backward to create distance.
The scales on Muten Natsu's body rippled as strands of black flames leaked out, restoring his ability to move.
"Infrasound?"
Sound waves with frequencies lower than twenty hertz are called infrasound.
When the natural vibration frequencies of parts of the human body, such as the abdomen or chest cavity, match the frequency of external infrasound, it causes resonance in the internal organs, damaging them.
If the vibration frequency of infrasound approaches the rhythm of the human brain and causes resonance, it can strongly stimulate the brain. Mild effects cause fear, agitation, and frenzy. Severe cases can cause sudden fainting, total loss of control, or even death.
Earlier, Kaname Tōsen had used this very technique to leave Rukia Kuchiki and her companions completely helpless.
"Suzumushi Nishiki: Benihikō!"
Kaname Tōsen swung his broken blade. Countless arm-length spikes split from the blade and shot toward Muten Natsu as he dove forward.
Muten Natsu's body flickered. Using Shadow Stealth, he slipped through the shadow cast by Benihikō and instantly closed the distance with Kaname Tōsen.
"Bankai... Suzumushi Tsuishiki: Enma Kōrogi!"
The ring on the guard of the sword spun and expanded, splitting into ten pieces that shot outward. A torrent of darkness burst forth, enveloping both of them inside.
Darkness swallowed everything before Muten Natsu's eyes.
Out of instinct, he spun his body, releasing ink blades and karmic flames to erode the space ahead.
In that instant, all sound, all light, even scent vanished from Muten Natsu's perception.
"Wah!"
Kaname Tōsen spat out another mouthful of blood beside him. The force of that earlier strike had shaken his internal organs.
But... there was no need to worry.
Bankai. Suzumushi Tsuishiki: Enma Kōrogi.
Within this pitch-black spherical space, a person's perception of Reiatsu, sight, hearing, and smell are all stripped away.
Inside this silent world of darkness and ignorance, only Kaname Tōsen, the wielder of Suzumushi, could move freely.
Suppressing his injuries with sheer force of Reiatsu, Kaname Tōsen raised his Zanpakutō beside Muten Natsu.
Even at such close range, Muten Natsu remained completely unaware.
"It really is... a familiar feeling." Muten Natsu smiled. "It reminds me of my days in Muken."
The deepest level of the underground prison, the Eighth Prison: Muken.
It was where Soul Society confined its most vicious criminals, those who, for various reasons, had escaped the Sōkyoku execution.
Prisoners in Muken were bound by Bakudō. Not only were they completely immobilized, their eyes were sealed as well.
Calling it imprisonment was inaccurate. It was closer to a seal.
Only darkness existed there. Or more precisely, it was a space where even darkness itself could not be clearly perceived.
There was no up or down, no left or right. A space without gravity.
Only a handful of people existed within Muken.
Yet Soul Society spent enormous resources to maintain this place for those few prisoners.
So the criminals could not perceive the world.
So they would be hidden from the world itself, until they eventually forgot the world even existed.
This vast void had been created by Soul Society to erase their existence.
"In that place, you can feel yourself slowly fading away into endless darkness," Muten Natsu said.
The scales on his left arm parted, revealing a translucent arm formed from black flames beneath.
"But I'm a little different. While I gradually lose myself, there's one thing that becomes clearer and clearer."
Kaname Tōsen sensed something was wrong and swung his sword at Muten Natsu.
"That thing is..."
The spiritual ink around the wounds on Kaname Tōsen's body suddenly ignited with black fire. The flames stretched through the darkness, wrapping around Muten Natsu's burning left arm.
Muten Natsu poured even more karmic fire into it. The thin strand of flame swelled like a massive serpent, coiling around Kaname Tōsen's body.
"Rage!"
Muten Natsu slashed down with his blade.
Kaname Tōsen was sent flying backward. His blood-stained body smashed through the boundary of Enma Kōrogi, and the space of darkness collapsed and vanished.
As soon as the light returned, Muten Natsu immediately locked onto Kaname Tōsen and rushed forward with another strike.
A razor-sharp blade suddenly thrust out from the side.
Muten Natsu instinctively tried to dodge, but his gaze shifted. Instead, he turned his sword sideways and blocked the incoming blade.
Nearby, Rukia Kuchiki and the others were not seriously injured, but they still couldn't move freely for the moment.
If Muten Natsu had dodged, that blade would have struck them.
"Looks like the sneak attack failed." Gin Ichimaru lowered the white cloth in his hand, shortening his Zanpakutō into a short blade. "My apologies."
"It's fine. There's still plenty of time." Sōsuke Aizen glanced at the severely wounded Kaname Tōsen before turning his gentle gaze toward Muten Natsu. "It's been a while, Muten."
"Aizen..." Muten Natsu stepped forward, shielding the others behind him. "What exactly are you trying to do?"
"Muten, I admired you from the very beginning. My expectations for you have always been far higher than for anyone else."
Sōsuke Aizen extended a hand.
"So step aside. Don't block my path."
Muten Natsu shifted slightly.
A powerful Reiatsu surged from his body, spreading outward before compressing back toward him.
As he compressed the Reiatsu, Muten Natsu gave his answer.
"Fuck you."