The Dangai was the spatial rift connecting the three realms. In this void, time and space lost all meaning—only endless darkness remained. Shinigami could only traverse it with the guidance of Hell Butterflies. Each time they entered to carry out missions, they had to hold their breath, proceed with extreme caution, and never linger too long.
The reason was simple: the Kōtotsu.A mysterious existence no Shinigami had ever fully understood. It drifted through the Dangai like a ghost, and whenever it appeared, it would bring devastating harm to any squad operating within.
The Seireitei was not without countermeasures. Through specialized devices planted in the Dangai, the Shinigami discovered that the Kōtotsu appeared roughly once every seven days. It required no reiatsu to exist, and whenever it appeared, it swept away anything in its path, cleansing the Dangai like a cosmic janitor. So long as they avoided its scheduled emergence, travel remained relatively safe.
Yet recently, the Kōtotsu had begun to appear far more frequently, disrupting missions and threatening lives.
In response, the Captain-Commander ordered the 10th Division Captain to personally lead his squad into the Dangai, with support from the 5th Division Vice-Captain and his team, to investigate the anomaly.
On the day of departure, hundreds of named and ranked Shinigami assembled. Their sheer numbers marching through Rukongai left the common souls trembling in awe and fear.
Among the crowd, a brown-haired man with a warm smile—Aizen Sōsuke—paused, as if noticing something.
"Aizen-fukutaichō, what is it?" asked the towering captain beside him.
"I just spotted a friend. May I take a moment to speak with him?"
The captain checked the time. "We have ten minutes before departure. Don't be late."
"Thank you, Captain."
Aizen nodded, then walked over to where a white-haired, blindfolded man sat casually on the ground with two bowls of ramen before him.
"Well, well. You came to see me off, didn't you, Yūshirō-kun?" Aizen smiled warmly.
"Sit. Eat."
Yūshirō didn't answer, only gestured to the bowls.
Aizen chuckled. "So you went out of your way to bring me ramen? I'm touched."
"Don't flatter yourself," Yūshirō scoffed. "The old ramen shop owner sent me. Last time, I mentioned how dangerous the Dangai is, that weaklings like you would die miserably. He panicked you'd never eat his ramen again and asked me to bring you a 'protection bowl.'"
Aizen's smile lingered. He picked up his bowl. "Fishcake ramen?"
Yūshirō lifted his own. "Bamboo shoot ramen."
Their eyes met. Both laughed lightly.
"Race you."
"Then I'll win."
Before Yūshirō could retort, Aizen was already slurping down noodles.
"Unfair!" Yūshirō dove in after him.
They ate at a ridiculous speed, finishing broth and noodles in seconds.
Aizen placed his empty bowl down with a smile. "Looks like I won, Yūshirō-kun."
"No way. You started early. If anything, I win."
"You were just slow."
"Then it's a draw."
"Agreed. We'll settle this next time."
Yūshirō packed up the bowls and left without looking back. "That is—if you return alive."
"I will," Aizen said softly, waving, then returned to the ranks of the Shinigami. Moments later, the gates to the Dangai opened, and the squad disappeared into its depths.
A month later, word arrived.
The 10th Division had discovered the truth: the Kōtotsu's rampage was caused by Quincy experiments. Survivors of the Quincy extermination war had been using the Dangai's countless subspaces—called Valleys of Screams—to hide. Their interference disrupted the natural balance, causing the Kōtotsu to spiral out of control.
The 10th Division Captain requested permission from Captain-Commander Yamamoto and Central 46 to launch a full-scale purge of these Quincy hideouts. Approval was granted.
Thus began what history would later call the Final Quincy Extermination War.It lasted not days, not years, but thirty long years.
The Quincy resisted fiercely, using spiritual threads called Thought-Silk to connect the Valleys of Screams like a web, enabling them to vanish before every Shinigami assault. Again and again, raids ended in failure, with years of scouting wasted the moment an attack was launched. Worse, the Quincy turned these webs into a guerrilla network, striking Shinigami squads from the shadows.
Then came the final blow—the sudden death of the 10th Division Captain.
"Why…?"
He never understood, even as a blade pierced his chest from behind.
"Farewell, Captain."
The smiling face of Aizen Sōsuke was the last thing he saw.
Standing before a gathering of Quincy, Aizen extended his arms."Now then, pierce me here, here, and here."
The Quincy fell to one knee in unison."We live to serve you, Aizen-sama!"
Arrows of light tore through his body—yet Aizen only smiled.
Moments later, Shinigami squads arrived, clashing with the Quincy in a bloody battle. Both sides fell in droves, and in the end, the Shinigami claimed victory, carrying back the corpse of their captain and the gravely wounded Aizen.
It was the year 1898.
The Seireitei mourned. The 10th Division was crippled. The survivors raged—not only had they lost so much, but it was at the hands of Quincy, the race they had once scorned as broken remnants.
The Central 46 and the Gotei 13 vowed vengeance. Plans were drawn to scour the Dangai and every Valley of Screams, to annihilate the Quincy once and for all.
As rain fell upon Seireitei, Yamamoto stood at his window in silence.
"Yo, old man," a voice called from behind.
Only a handful dared address him that way. He didn't need to turn to know who it was.
"You refused the rank of captain," Yamamoto said sternly. "Why are you here?"
The man shrugged casually. "I'm not here for titles. I just want the Quincies hiding in the Dangai. Leave them to me."
"…To you?" Yamamoto turned, narrowing his eyes at the pale-faced man.
"That's right. Recently, I visited a friend of mine. Poor bastard's stomach was destroyed, his organs ruined. The 4th Division said it was a miracle he even lived. I want to see what kind of monsters could do that. You wouldn't deny me that, would you, old man?"
Yamamoto stared at him for a long moment, then closed his eyes.
"Very well. I leave it to you."