"Mayuri Kurotsuchi, that madman… He was already thinking about creating artificial Shinigami a hundred years ago."
Masatsuki Aozaki flipped through Mayuri Kurotsuchi's research notes, clicking his tongue in admiration.
"Too bad Gikon technology didn't exist back then, and neither did Mod Soul technology. He had to figure it all out from scratch… That must've been a nightmare."
The foundation of Gikon technology was based on Kirio Hikifune's temporary soul techniques, while Mod Soul technology had yet to be developed even now.
For Mayuri to tackle such a difficult project alone—it was no surprise how challenging it had been.
But his efforts weren't entirely fruitless.
Masatsuki flipped open another notebook.
Inside, it documented a technique—one that could completely isolate Reishi.
As he read through it carefully, a realization struck him.
"No wonder this guy wanted to research the Quincy!"
This technique had been developed by studying how Quincy manipulate Reishi.
It involved constructing a stable Reishi membrane to cut off the interaction between external and internal Reishi.
Mayuri had stumbled upon this method during his research into artificial Shinigami bodies.
His theory was that this technique could prevent artificial Shinigami souls from being too fragile, stopping Reiatsu loss and preventing soul disintegration.
"Wait… Suppressing Reiatsu!?"
Masatsuki's eyes widened, and he let out a startled gasp.
Something clicked in his mind.
Ordinary Mod Souls were high-density Reishi bodies designed to help Shinigami recover their lost powers.
But the version Kisuke Urahara developed later was different—a Reishi body devoid of Reiatsu, functioning in the exact opposite way.
Then he recalled something Aizen had once mentioned—external Reiatsu could react with the soul's internal Reiatsu inside the Hōgyoku, affecting its formation.
A terrifying possibility formed in Masatsuki's mind.
Could it really be just a coincidence?
Was this Reishi isolation technique actually the key to creating the Hōgyoku?
Masatsuki closed his eyes, forcing himself to recall what he knew about Bleach.
In his hazy memories…
Aizen had once said he hadn't expected Kisuke Urahara's Hōgyoku to be so small.
From that, it could be inferred that Aizen's failed Hōgyoku must have been massive.
And before Aizen fused with it, the Hōgyoku had always been sealed inside a thin membrane.
Could it be that Kisuke had used a Reishi isolation technique when developing the Hōgyoku?
Of course, this was all just speculation on Masatsuki's part. The only way to confirm it would be through actual experimentation.
But right now, he didn't even have the basic materials needed to create a Hōgyoku. He hadn't even made anything resembling Aizen's prototype.
Thinking about it was pointless without the foundation to test it.
Masatsuki gently brushed the dust off the notebook, tucking it into his robe for safekeeping.
Looking around the underground lab, his eyes suddenly gleamed with excitement.
What once seemed like an abandoned, century-old laboratory now looked like a treasure trove overflowing with gold.
"No way… If Mayuri Kurotsuchi left all this for me, I can't let it go to waste."
With that, Masatsuki wasted no time. Using both hands, he grabbed two pieces of equipment and dashed toward the Kagarashi District.
Back when he first attempted to create the Hōgyoku in Rukongai, he had secretly built a hidden chamber beneath the outskirts of the Kagarashi District to avoid drawing attention.
After his initial experiments failed, that chamber had since become his storage for collected souls.
Masatsuki Aozaki wasn't comfortable leaving all these valuable things in someone else's hands.
So he decided to move everything to his own secret base—whatever couldn't be transported, he'd destroy.
The whole operation took a full thirty minutes.
If he hadn't remembered midway that he could use Bakudō #37: Tsuriboshi to create a small hammock for transport, it would have taken even longer.
This was the deal he had made with Mayuri Kurotsuchi.
Masatsuki had given Mayuri a reason to enjoy life again in the Nest of Maggots and promised him freedom in return.
And Mayuri had handed over everything he once possessed.
For Masatsuki, this was an absolute win—not to mention that some of the technology he obtained could very well be related to the creation of the Hōgyoku.
The makeshift equipment he had set up for Mayuri in the Nest of Maggots was practically junk compared to what was in this lab.
These machines might look old and bulky, but they were far more advanced, capable of conducting a much wider range of experiments.
For a moment, he was tempted to restart his own Hōgyoku experiments.
...
Masatsuki stepped out of the secret chamber. The sun had already risen, casting a golden glow in the east.
Despite having spent the entire night awake underground, he felt no exhaustion—if anything, he was more energized than ever.
Mayuri's findings had been beyond his expectations. He still hadn't fully processed everything.
After a while, he returned to Seireitei.
...
Kisuke Urahara stretched and let out a yawn.
"So, what brings you here so early in the morning?"
"You look exhausted."
"Stayed up all night working on the protective gear. I was just catching up on sleep in my office when you dragged me out."
"Sleeping during the day, staying up all night… Not bad. Just like my external brain—our lifestyles are practically the same."
"Don't assign me some weird title," Kisuke retorted. "I just think more clearly at night. It's easier to find inspiration."
"So, did you come to take advantage of my half-asleep state and trick me into becoming your external brain?"
"Of course not." Masatsuki waved a hand dismissively. "Actually, I need a favor."
Kisuke sighed, rubbing his temples.
Was this all he was to them?
Whenever they needed something, they'd come find him. And when they didn't, they'd team up with Yoruichi to mess with him.
What kind of friendship was this?
Was he just their personal handyman? Or some unwilling participant in their bizarre games?
His eye twitched as he gritted his teeth.
"What do you want?"
Masatsuki clapped a hand on his shoulder, offering a reassuring pat.
"It's about Yoruichi. She came to see me last night… and mentioned Kūkaku."
The moment Kisuke heard Yoruichi and Kūkaku's names in the same sentence, a knowing smirk spread across his face.
After all, he was the one who had started this whole situation. Everything was unfolding just as he had planned.
A good friend always returns a prank with another prank.
"Let me guess," Kisuke mused smugly, "Yoruichi found out you were giving Kūkaku a protective suit and got jealous?"
He leaned forward, clearly enjoying himself.
"She's been running all over looking for you, so now you've come to hide out with me?"
"No." Masatsuki shook his head.
Kisuke blinked. "...Huh?"
"She was a little upset at first, but after I promised to get her a gift, she ran off excitedly."
Masatsuki frowned slightly.
"I have no idea what's going on with her, but I made a promise, and I intend to keep it. That's why I came to ask you to make a gift for me."
Kisuke pondered for a moment, unable to figure out what Yoruichi was thinking either.
After a brief pause, he asked, "What kind of gift?"
"A necklace—something like the one she usually wears." Masatsuki's expression brightened. "If it could change size at will, that'd be ideal. And if it could transform into a weapon… even better."
(40 Chapters Ahead)
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