After one last look in the direction Rukia Kuchiki and Orihime Inoue had gone, Muten Natsu turned and followed Retsu Unohana toward the Senkaimon.
"Muten Natsu."
Muten Natsu turned toward Seinosuke Yamada, who had called out to him. "Hmm?"
"You..." Seinosuke Yamada shook his head. "Never mind."
The Senkaimon closed, vanishing before his eyes.
What appeared in its place was a purplish-black Kōryū. It was impossible to tell whether it was liquid or a current of air.
Muten Natsu asked Retsu Unohana in confusion, "What was he trying to say just now?"
Retsu Unohana walked forward at an unhurried pace. "The Yamada family has always been part of the nobility. And since he is now the Chief Representative of the Shin'ō Medicine Institute, he has naturally heard certain things from other elderly nobles."
"Certain things?" Muten Natsu touched his cheek, then brushed his fingers over his lips, warmth softening his eyes. "What kind of things?"
"For example, before I joined the Gotei 13..." Retsu Unohana stopped and drew her Zanpakutō. "I was known as the greatest evil in the history of Soul Society, without precedent and without equal."
Muten Natsu's body went rigid in an instant. A massive wound opened across his chest.
Blood sprayed from it, splattering across Retsu Unohana's expressionless face.
Muten Natsu fell backward powerlessly. The chaotic purplish-black Kōryū writhed closer, ready to swallow him whole.
...
Tap, tap, tap.
"What the hell... What is going on right now...?" Keigo Asano ran while scanning his surroundings. People lay collapsed all along the roadside. "Everyone's asleep on the street... The cars and traffic lights have all stopped too..."
The city seemed dead, leaving only the sound of Keigo Asano's footsteps.
"This is way too creepy... Why does this feel like the end of the world...?" Keigo Asano was so panicked he was nearly in tears. "Am I dreaming...? Or are they filming a movie?"
"Please!" Keigo Asano wailed in terror. "Is anyone watching this? Where's the camera or whatever...? And also, aaaaah!"
Keigo Asano screamed and clutched his struck nose. "This familiar feeling... Ichigo?! No..." He stared blankly at the person who had just taken him down with a lightning-fast lariat. "Arizawa!"
Seeing a familiar classmate at a time like this, Keigo Asano was overjoyed. "Thank goodness! I mean, it's you, but at least you're human! Did you see what's happening around us? Everyone's asleep! Seriously, I thought I was the only person awake in the whole world. I felt so lonely! But there's someone else awake too, that's such a relief! Actually, I wasn't worried about you or anything! If anything, I'd rather someone worry about me... Oh, right, have you seen Mizuiro? I can't find him anywhere... And why did you hit me just now, urk!"
"You're too loud." Tatsuki Arisawa finally lost her patience and knocked Keigo Asano down with one punch.
That was why she had hit him.
"S-sorry... I got too excited."
"Shut up," Tatsuki Arisawa snapped, glaring at him. "I just went outside town. The whole town disappeared out there, and the ground looks like it was cut clean off. It's hard to believe, but that's exactly what happened. It's like all of Karakura Town was sliced out like a piece of cake and moved somewhere else."
"So what do we do?"
"First, we find the others and meet up, then we figure out a plan." Tatsuki Arisawa forced herself to stay calm. "There should be other people awake too."
She did not say it aloud, but Tatsuki Arisawa already had a guess.
This was probably connected to Muten Natsu.
And if it was Muten Natsu...
He would definitely be able to fix it.
...
The Dangai, as its name suggested, was a place cut off from both Soul Society and the World of the Living, with time and space isolated from each side.
Located between Soul Society and the World of the Living, this space was formed from overlapping layers of severed space and tightly surrounded by torrents of time. Its time density was two thousand times greater than the outside world, and in the past, Shinigami often used it as a place to exile criminals.
That was why the Kōryū and Kōtotsu existed there.
The surging Kōryū bound spiritual bodies, preventing them from leaving the Dangai until death.
As for the Kōtotsu, which appeared once every seven days, it annihilated everything in its path.
Muten Natsu lay in a pool of blood as the purplish-black Kōryū closed in on his body. Not far away, a brilliant golden light flared. A huge, unknown object rushed toward him like a speeding train, and it was none other than the Kōtotsu, the thing that destroyed everything.
Retsu Unohana raised her hand and swung the Zanpakutō in her grip, its curve far greater than that of an ordinary blade.
A cold gleam flashed. The approaching Kōryū scattered in an instant, and the speeding Kōtotsu shattered with it. For a moment, the massive bones inside could be seen, their broken edges smooth and clean.
The golden light faded. The exposed spherical object fell and rolled into the Kōryū.
The Kōtotsu was not Reiatsu, but a theoretical entity. That was why it could move freely through the Kōryū. Attacks from spiritual bodies were completely ineffective against it.
But Retsu Unohana had not attacked it with her Zanpakutō.
What cut the Kōtotsu apart was the blade pressure, sharpened to an extreme.
With nothing more than the gale stirred by a swing of her Zanpakutō, Retsu Unohana had effortlessly destroyed the Kōtotsu.
"Stand up, Muten Natsu." Retsu Unohana looked down at Muten Natsu on the ground. Her usually gentle eyes now held only the cold indifference of someone looking at trash. "Weak as you are, an injury of this level shouldn't be fatal."
"I..." Muten Natsu struggled to prop himself up with his arms. The wound across his chest was deep enough to expose bone, yet he paid it no attention. He simply sat there in a daze, staring blankly at Retsu Unohana. "I don't understand..."
"You don't understand?" Retsu Unohana raised her Zanpakutō. "Even though... the battle has already begun."
"Why...? Why do I have to fight you...?" Muten Natsu searched Retsu Unohana's face for the gentleness she had always shown him, but found nothing. Then something suddenly occurred to him. "Kyōka Suigetsu... This must be Kyōka Suigetsu!"
The curved blade swept past, cutting open Muten Natsu's shoulder.
"This is not hypnosis, Muten Natsu." Blood dripped from the blade in Retsu Unohana's hand. "This is the truth. The truth that Retsu Unohana is going to kill Muten Natsu."
"No..." Blood streamed from his shoulder as Muten Natsu clenched his teeth. "You..."
"I saved you so many times, so there would be no reason for me to kill you now, right?" Retsu Unohana lowered her eyelids slightly. That tiny shift alone made her shadowed face take on a bone-chilling coldness. "Wrong. It was because there was no reason to kill you before that I saved you so many times."
Muten Natsu staggered to his feet. "I... I'm going to find Aizen... I'm supposed to fight him..."
"You've had doubts for a long time. Why I saved you, why I helped you, why I grew close to you... But you never wanted to face those questions." Retsu Unohana saw straight through Muten Natsu's evasion. "Think back. What happened when we first met?"
Retsu Unohana reached up and untied the braid bound in front of her chest. Soft strands of black hair fell to either side, revealing the blood-red scar at the center of her collarbone. Wild and fierce, it looked like a red spider lily blooming against her smooth, snow-white skin.
The bewitching scar entered his vision, awakening a memory Muten Natsu had never forgotten.
When they had first met, the first time Muten Natsu used the Hell Flames, he had burned Retsu Unohana's body and gained tremendous power.
And left that scar behind.
"At the time, you had not yet mastered Myōki's power, but you already possessed it. While burning my body, you also used Myōki to obtain my Reishi," Retsu Unohana said softly. "That Reishi formed a special existence inside you, something you call the Primordial Form."
Muten Natsu's breath caught. "So..."
"So when you were tormented by the Primordial Form, you could only sleep well at my side." Retsu Unohana gave him the answer. "It wasn't that I used Reiatsu to suppress the Primordial Form. I was feeding Reiatsu into it, helping it grow further. During that process, the Primordial Form would fall dormant."
"Grow...?"
"I told you, didn't I? The Primordial Form uses your power. If it can absorb my power to grow, then it can also absorb your power to grow." Retsu Unohana's pale fingertips stroked the blood-red scar. "Blossoming and bearing fruit... The flower blooms on me, while the Primordial Form inside you is the fruit. I've waited so long. At last, the harvest has come."
Muten Natsu's mind was a mess. "No... It shouldn't be like this..."
"When you mastered your Bankai, I was worried you might notice." Retsu Unohana lightly swayed the Zanpakutō in her hand. "But in the end, you ignored it."
"My Bankai...?"
"Because of the influence of my power, your power is quite similar to mine." Retsu Unohana prompted him, "Didn't you notice... Rin'en Bokukō and Minazuki are rather alike?"
Muten Natsu remembered that time. When he was on the verge of death from overusing the Hell Flames, Retsu Unohana had saved him with her Bankai. "But Bokukō's Shikai..."
"Is very similar to my Bankai." Retsu Unohana reached out, gripped the blade of her Zanpakutō, and pulled the hilt. "Bankai. Minazuki!"
The blade cut into her palm, and thick crimson blood flowed out. As Retsu Unohana spread her arms, the blood followed the curve of the blade, forming a crimson half-circle of blood in front of her before dripping down in heavy drops.
In an instant, it was impossible to tell whether the blood had surged into the sky or fallen from it.
A dense reek of blood rose. Viscous blood gathered into a pool, swallowing Muten Natsu within it.
All he could see was crimson. Terrifying Reiatsu filled his mouth and nose, and every breath carried the taste of blood.
White smoke rose from the wounds on Muten Natsu's body as they healed at a terrifying speed. "What...?" He touched his restored body. "This is completely different, isn't it?"
His Bokukō had no healing ability at all. It only corroded enemies.
"You're still..." Retsu Unohana's cherry lips parted slightly. "As naive as ever."
Muten Natsu watched the flesh of his fingertips dissolve, exposing stark white finger bones in the bloody mist.
Was this... the corrosion of Spirit Ink?
No. Unlike Spirit Ink's corrosion, which ate from the outside in, Minazuki's corrosion came from the inside out.
"I meant to wait until you had grown a little more before harvesting you, but... this is all you amount to." Retsu Unohana swung her left arm, turning her body as her right arm rose with the motion. "You have disappointed me, Muten Natsu."
A crimson blade of blood left her Zanpakutō and sliced open Muten Natsu's shoulder.
The horrific wound healed rapidly within the bloody mist. Muten Natsu pressed a hand to his shoulder. "Why...?"
"Why heal you? This is... forced ripening." Retsu Unohana swung her Zanpakutō casually, sending scattered blades cutting through Muten Natsu's body. "I will repeat the process of healing and wounding you over and over. By wearing down your body, I will wear down your will. Everything you possess will become nourishment for the Primordial Form. Once your consciousness has completely vanished, I will obtain all of the Primordial Form's power."
"I'm asking you..." Muten Natsu swayed under the slashes of the blood blades. "Why do you want power?"
"To enjoy battle." Retsu Unohana stopped attacking. "As the first-generation Kenpachi who founded the 11th Division, I want greater power. I want to enjoy battles on a higher level... Surely you can understand that."
"So..." The hilt of Myōki emerged from Muten Natsu's left palm. "You saved me to obtain greater power."
"That's right."
Muten Natsu gripped the hilt. "Your embrace..."
"Was to make the Primordial Form grow faster."
Muten Natsu's voice was hoarse. "Then what about the way you cared for me? Your teaching... What was all that affection supposed to be?"
"You already know the answer, yet you still want me to say it?" Retsu Unohana frowned slightly. Her half-lidded eyes held no warmth at all. "It was not affection or care for you. It was protection and attention directed at the Primordial Form inside you."
Muten Natsu's trembling hand finally steadied. Myōki broke free from his left arm, viscous Spirit Ink spilling out.
"Oh, yes... There was one more reason." Retsu Unohana seemed to have only just remembered. She showed him a gentle smile, though her eyes remained cold. "The kinder I was to you, the greater the shock you would suffer now. And the faster I could... wear down your will."
A stark white skull mask covered his cheeks. Muten Natsu ignited the Hell Flames and leapt from the bloody mist, bringing his blade down in a single slash.
Retsu Unohana casually deflected Myōki. Her blood-dripping Zanpakutō met Muten Natsu's neck.
With the slightest pressure, she cut open his throat.
Muten Natsu fell helplessly into Retsu Unohana's arms. That familiar warmth left him dazed for a split second.
And in that moment, the blood-soaked blade pierced his chest.
"In battle..." Retsu Unohana took a step back and let Muten Natsu fall into the pool of blood. "How could you embrace your enemy?"