Mayuri Kurotsuchi took the book Nemu Kurotsuchi had brought and flipped through it rapidly, yet with meticulous attention.
"This so-called Ōin... what exactly is it made of? The manufacturing process... the craftsmanship... the principles behind its functions... Finally, my brain cells are starting to boil again, ne~"
Mayuri Kurotsuchi went through one book after another, hungrily absorbing new knowledge while constantly complaining.
"When will these people learn to record facts properly instead of wasting pages and time on tedious, useless descriptions, ne..."
Boom!
A violent explosion interrupted Mayuri Kurotsuchi's thoughts.
Characters rapidly refreshed before his eyes. He set the book aside, gave a cold snort, and rose to his feet.
"They actually brought their trouble all the way here..."
Three minutes earlier, while Mayuri Kurotsuchi had been immersed in his thirst for knowledge, the alarms in the Research and Development Institute's observation room suddenly began blaring, signaling an invasion by Ryoka.
"What's going on?"
When everyone looked toward the alarm system, their first thought was that the observation equipment had malfunctioned.
"How is that even possible?"
The instruments indicated that a powerful Arrancar had appeared inside Seireitei.
Its location was...
A chill suddenly ran down Akon's spine.
And he wasn't the only one.
Over the span of only a few seconds, the squad members froze one after another, starting with those who had the sharpest spiritual perception.
In the deathly silence, the smooth clacking of a keyboard sounded from a desk at the back of the room.
Everyone slowly turned their heads as though their necks had rusted stiff.
An Arrancar was sitting in the Director's chair, calmly operating the computer.
The instruments said that a powerful Arrancar had appeared inside Seireitei.
And his location was this very observation room.
Click.
Under everyone's stunned gaze, the man in the Director's chair finished typing.
Looking at the information displayed on the screen, the corners of his lips curved into a faint smile.
"Oh... So the person who defeated me is the Director here."
He raised one hand to adjust the mask resembling a pair of glasses and spoke in a cold, cutting voice.
"I truly pity all of you~ Working under someone so reckless, I doubt you're ever able to make proper use of your abilities."
The man's voice was completely unfamiliar to those present.
But every one of them remembered his face vividly.
"Hey... This guy..."
"Isn't he supposed to be soaking in preservative fluid?"
"The specimen escaped?"
Specimen.
The instant the Arrancar heard that word, his eyes narrowed.
Then he suddenly burst out laughing.
"Specimen... Ha! So I've even become a specimen! I expected something like this, but actually having it confirmed is far more humiliating than I imagined! It may only be my corpse, but I never thought there would come a day when I became the subject being observed!"
This is bad...
Akon watched the unstable excitement spreading across the man's face.
If this man really was the same person as the specimen stored inside the Institute...
Then they were in serious trouble.
This was No. 8 of the Espada, Szayelaporro Granz.
"Let me see that specimen." The Arrancar rose from the chair. "Opportunities to observe your own corpse aren't exactly common, after all... Hm. I barely even remember dying in the World of the Living."
Akon struggled against the terrifying pressure of his Reiatsu.
"...You say that like you actually remember some of it."
Lower-tier Menos were formed from the fusion of countless Hollows.
Higher-tier Menos were created through lower-tier and middle-tier Menos devouring and merging with one another.
There was no reason they should retain the memories of a single individual from before those countless fusions.
"...And in a situation like this, that's what catches your attention?" The Arrancar shook his head. "I see. You really are a researcher through and through."
He gave Akon a contemptuous glance.
"But I have no obligation to answer you. Honestly, I have no interest whatsoever in people of your caliber, either as Shinigami or as scientists."
Akon fought down the instinct to retreat.
"You barge into someone else's research institute and still have the nerve to act so arrogant."
"That's enough small talk. Anything you want to know, investigate with your own abilities."
The Arrancar reached toward the Zanpakutō at his waist.
"Assuming you live long enough to do so."
Almost simultaneously, Akon flung several test tubes from his sleeve.
The other members of the Institute immediately sprang into action as well.
Boom!
Amid the violent explosion, the Arrancar's laughter rang out.
"I see. I thought disposing of all of you would be effortless, but apparently you do possess enough skill to call yourselves members of the Research and Development Institute. Unlike ordinary Shinigami, each of you has a few unusual tricks."
The members of the Research and Development Institute standing before him had all been injured.
Yet not a single one of their Reiatsu had disappeared.
"Since I've been given such a rare opportunity, I'll take my time observing all of you when I dispose of you later."
Without attacking again, the Arrancar walked deeper into the damaged Institute and stopped before a massive cylindrical tank.
Several research specimens were preserved inside the transparent container.
The Arrancar's gaze settled on one specimen submerged in faintly glowing liquid.
Although there could be individual differences, once an Arrancar was killed by a Zanpakutō and its soul purified, its body would normally disappear.
Mayuri Kurotsuchi had used a special apparatus to prevent that from happening and preserve this particular specimen.
"Haha. It looks exactly like the data sent back by the Spirit-Recording Insects. I didn't even realize I was dead. Just look at that stupid expression."
The Arrancar stared at the face identical to his own and placed a hand against the surface of the tank.
Then he turned toward the 12th Division security personnel who were still conscious.
"You should celebrate. Before you die, you'll have the privilege of witnessing the exceedingly rare moment when a dead body and its soul are reunited."
As though the glass around the tank were nothing more than an illusion, the Arrancar pushed his hand straight through it with a smug smile.
But the moment his fingers touched the corpse's wrist, that smile vanished.
Confusion appeared first.
Then irritation.
And finally, a deliberately restrained calm.
"What... did you do?"
Seeing the equally confused expressions on the Research and Development Institute members' faces, the Arrancar immediately understood.
"Mayuri Kurotsuchi... So that bastard did something to it...!"
The moment he spoke the Director's name, unmistakable hatred and killing intent appeared in his eyes.
His increasingly violent gaze settled upon the wounded members of the Institute.
But a moment later, he pushed up his glasses-shaped mask and restored his arrogant smile.
"You should consider yourselves fortunate. Your lives have just been extended for a little while longer..."
The Arrancar's figure gradually faded along with his voice, disappearing without a trace as though melting into the surrounding space.
The specimen inside the tank he had touched vanished in exactly the same way.
At the same time, explosions erupted simultaneously throughout several locations in the Research and Development Institute.
...
"That's everything that happened. I'm sorry, Director. With our abilities, the most we could manage was protecting the backup data storage room."
Akon offered no excuses and lowered his head in admission of fault.
"At present, the greatest damage is to Seireitei's communications and our monitoring of the Dangai. There's also..."
"We can determine the rest by extracting and analyzing the bacteria implanted in your bodies."
Mayuri Kurotsuchi looked around at the devastated Research and Development Institute.
"His interference with my systems lasted only briefly. Once my autonomous decryption system activated, he tucked his tail between his legs and fled. However, that method of disappearing..."
Akon recalled their earlier observation results.
"Compared with the footage captured by the observation insects in Karakura Town, the way he disappeared was identical to the Arrancar woman who appeared there."
"Hmph..."
Without showing the slightest concern for his injured subordinates, Mayuri Kurotsuchi issued his orders coldly.
"Restore communications as quickly as possible. And... Inaba, restore our monitoring of the Dangai as well. It's been used rather frequently lately."
"Yes."
Kagerōza Inaba lowered his head in acknowledgment, one hand pressed against the wound on his shoulder.
A faint smile appeared on his face.
...
"Matsumoto~"
Momo Hinamori waved.
"I couldn't get through on the phone at all. I was starting to think something had happened."
"There's probably some problem over at the Research and Development Institute. Don't worry about it. They should have everything working again soon."
Rangiku Matsumoto smiled.
"Anyway, forget about that. Since you've come all the way to the World of the Living, you should take the opportunity to relax. You've been pushing yourself too hard lately."
"I'm actually fine... Staying busy makes me feel more at ease."
Momo Hinamori glanced around.
"Um..."
Rangiku Matsumoto immediately guessed what she was wondering about.
"If the Captain hadn't sensed where you were, it would've taken me quite a while to find you."
"Then Tōshirō..."
"He said there were still some things he needed to take care of afterward, but..." Rangiku Matsumoto winked. "He asked me to take you somewhere first."
Momo Hinamori's eyes widened slightly.
She could vaguely guess what Tōshirō Hitsugaya might be doing.
Was he...
Preparing some kind of surprise?
With that thought in mind, Momo Hinamori followed Rangiku Matsumoto.
But the farther they walked, the more secluded their surroundings became.
"You need to close your eyes here," Rangiku Matsumoto reminded her.
"Huh?"
Momo Hinamori hesitated briefly, then closed her eyes.
"Just keep walking forward slowly."
As she spoke, Rangiku Matsumoto gripped the Zanpakutō behind Momo Hinamori.
Clang!
A sharp metallic sound rang out.
Momo Hinamori immediately opened her eyes.
Standing between her and Rangiku Matsumoto was Tōshirō Hitsugaya.
"Tōshirō?"
Tōshirō Hitsugaya swung his blade and forced Rangiku Matsumoto backward.
"Muten!"
Pitch-black Spirit Ink came pouring down.
The moment it landed on Rangiku Matsumoto, black smoke began rising as the ink corroded her body.
Strands of black smoke were absorbed by Myōki.
Muten Natsu stared at Rangiku Matsumoto.
"Reigai."
The next instant, bitterly cold ice completely encased Rangiku Matsumoto.
"Hinamori."
Tōshirō Hitsugaya turned toward her.
"Are you all right?"
"What is going on?" Momo Hinamori stared at them in confusion. "Why is this happening?"
"Before we explain..."
Muten Natsu approached her.
Spirit Ink seeped from his fingertip and fell onto Momo Hinamori's hand.
Black smoke immediately rose from the point of contact.
"She's real."
Tōshirō Hitsugaya visibly relaxed.
"This isn't the place to talk. Let's..."
Before he could finish, the Reigai of Rangiku Matsumoto trapped within the ice suddenly ignited with an eerie green glow.
The flames completely engulfed her.
"Damn it..."
Tōshirō Hitsugaya moved protectively in front of Momo Hinamori, his expression grim.
"Looks like we won't be able to take her back with us. Let's head to Urahara's Shop first. Urahara can explain everything more clearly."
Inside Urahara's Shop were not only Muten Natsu, Tōshirō Hitsugaya, and Momo Hinamori.
Rukia Kuchiki, Orihime Inoue, and Retsu Unohana were there as well.
So were Nozomi Kujō and Ririn.
And there was another Muten Natsu.
"...And that, in summary, is what a Reigai is."
Kisuke Urahara lightly tapped his folding fan against his palm, then gestured to the side.
A hat-wearing Muten Natsu stepped forward and stood face-to-face with the real Muten Natsu.
Muten Natsu carefully sensed him.
Even with his rather dull spiritual perception, the difference was obvious.
"There's a clear difference in Reiatsu."
"That's because Kurōdo hasn't absorbed your Reishi yet," Kisuke Urahara explained. "Once he obtains the necessary Reishi, he can copy not only a person's appearance, but also their Reiatsu and even the abilities of their Zanpakutō. Kurōdo, would you mind demonstrating?"
The man called Kurōdo removed his hat and gave a slight bow.
When he put the hat back on, he had already transformed into Kisuke Urahara.
He drew the Zanpakutō from the cane in his hand.
"Awaken, Benihime!"
Bathed in crimson light, the Zanpakutō transformed into Benihime.
"You deliberately chose your own appearance for the demonstration..." Retsu Unohana raised her eyes. "Is that because he can't do it using Muten's appearance?"
"I only discovered that myself just now."
Kisuke Urahara spread his hands.
"Kurōdo can't make use of Muten's Reishi."
"His Reishi contains a peculiar power."
Kurōdo transformed again, this time taking the form of a middle-aged man with a small mustache. He adjusted the black top hat on his head.
"I'm unable to read the information contained within it effectively."
"Kujō-san."
Kisuke Urahara turned toward Nozomi Kujō, who was clutching her left arm.
"As you can see, I've already managed to create a Reigai. I don't believe there's any need for you to keep hiding the truth anymore."
With the situation in Soul Society uncertain, and Nozomi Kujō, who was suspected of being a Reigai, staying here, Muten Natsu had decided to come to Urahara's Shop.
But Nozomi Kujō had refused to reveal anything.
Reigai were extremely dangerous.
She couldn't be certain what the people before her would choose to do after learning what Reigai were capable of.
But now Kisuke Urahara had managed to create something similar to a Reigai in an extremely short amount of time.
There was no longer any reason for her to keep the truth hidden.
"Both Kagerōza Inaba and I are Reigai created by Ōko Yushima."
Nozomi Kujō's expression remained indifferent, her voice cold and clear.
"After Ōko Yushima developed the Reigai, Central 46 rejected the plan to mass-produce them. Before he was arrested, Ōko Yushima divided his own Soul into two parts, altering his Reiatsu in an attempt to evade capture. He also sealed away all of his research data and cast it into the Dangai. Its whereabouts were unknown."
She paused.
"Until... the Kōtotsu inside the Dangai was destroyed, giving me the chance to leave the Valley of Screams."
It was Retsu Unohana who had destroyed the Kōtotsu.
The situation at the time had been critical. To give Muten Natsu enough time to grow stronger, Retsu Unohana had been forced to destroy the Kōtotsu that appeared.
As for the Valley of Screams...
"The Valley of Screams is a place within the Dangai where displaced Souls gather," Kisuke Urahara explained. "It continues to exist as a space composed of Reishi."