The true ability of Aizen's Zanpakuto had only been revealed by Aizen himself to Unohana after his faked death, to satisfy her curiosity.
Before that moment, despite Kisuke and others having many theories about Kyoka Suigetsu's power, none could be confirmed.
Now, with Gin exposing the Complete Hypnosis Ability, and connecting it with all the strange events in Seireitei over the years, everyone quickly realized his information was accurate.
Kyoka Suigetsu's power to completely control the five senses of anyone who witnessed its hypnosis ceremony was indeed terrifying enough to manipulate all of Seireitei's Shinigami.
The permanent nature of this control meant that in any confrontation with Aizen, they wouldn't even be able to distinguish reality from illusion.
How could they possibly fight under such conditions?
Unless...
Someone had never witnessed Aizen's hypnosis ceremony!
Or, like Kyoya, they could somehow see through Kyoka Suigetsu's illusions, giving them a chance to face Aizen directly.
But every Shinigami in Seireitei, including those who had fled like Kisuke's group and the Visoreds, had undoubtedly been placed under Aizen's hypnosis.
This meant none of them currently stood a chance against Aizen.
Any confrontation would be suicide.
Unless... they could train a new Shinigami capable of fighting Aizen?
Kisuke's eyes drifted toward Masaki on the medical bed.
As the creator of the Hogyoku, Kisuke possessed fundamental understanding of Reiryoku.
Currently, Kurosaki Masaki's body contained three distinct powers in perfect balance: Quincy, Hollow, and Shinigami.
Though she couldn't utilize the latter two due to her Quincy nature...
If she were to have a child with a Shinigami, that child would undoubtedly become a natural prodigy capable of wielding all three powers!
And that Shinigami-
Kisuke's gaze settled on Isshin, his decision made.
But first, they needed to fully understand Aizen's abilities.
"Captain Gin," Kisuke asked, "what exactly is Aizen's hypnosis ceremony?"
"Shopkeeper Kisuke," Gin's eyes narrowed to slits, "Why would I simply give you Aizen's weakness?"
While Gin was happy to see Kisuke's group cause trouble for Aizen, he wasn't about to hand over hard-earned intelligence for free.
What truly annoyed him was Tessai's earlier threat toward Rangiku when she protected him.
That he hadn't immediately drawn his Zanpakuto was restraint enough.
Expecting him to reveal Aizen's secrets now?
Absolutely not.
Did they think he had no pride?
Kisuke was no fool.
He could see Gin's indifference toward them clearly.
'This guy really is similar to Kyoya...'
From this alone, Kisuke understood that Gin, like Kyoya, paid little attention to those outside his interests or who hadn't directly opposed him.
Kyoya's perspective was understandable, as he had greater ambitions.
Through Yoruichi, Kisuke had learned about the changes in Rukongai over recent years.
Even he had to admire what Kyoya had accomplished.
However, Kisuke couldn't approve of Kyoya's methods.
The Seireitei served as the 'observer' and 'coordinator' maintaining balance across the three worlds.
Regardless of its flaws, it had preserved stability for millions of years.
Kyoya's revolution in Rukongai threatened to disrupt that delicate balance.
If conflict erupted between Rukongai and Seireitei, the consequences for all three worlds could be catastrophic.
Suppressing a Rukongai Rebellion would devastate the Gotei 13's forces.
If Hueco Mundo seized that opportunity to invade, all three worlds could face destruction.
No one could expect Hollows to care about 'maintaining balance'-
The original Hollow from a million years ago had possessed the terrifying desire to devour all souls.
Had the world's 'will' not created the Soul King to destroy that ancient Hollow, existence might have already descended into chaos.
Only the noble families who used the Soul King's power to create the three worlds understood how to maintain Reishi Balance, utilizing the 'backdoors' they'd left, the Senkaimon, to connect the worlds.
Hollows naturally opening Garganta was their unique ability.
If Seireitei's forces were severely weakened, large-scale Hollow invasions of either the Soul Society or living world could disrupt the fundamental Reishi Balance.
With his intelligence, Kisuke knew conflict between Rukongai and Seireitei was inevitable.
Not just one battle, but likely many.
The victor would hold Seireitei and claim 'legitimacy'.
The defeated would retreat to Rukongai, waiting centuries or millennia until they could challenge again.
As for Gin...
Though he hid it well, Kisuke had caught the subtle shift in his gaze earlier.
Kisuke looked toward Rangiku, then addressed Gin: "Captain Gin, years ago I developed a device."
"It can forcibly materialize a Zanpakuto's Spirit."
"If the Shinigami can defeat this manifested spirit, they can achieve Bankai."
"Lieutenant Matsumoto possesses remarkable skill, but her Reiatsu hasn't yet reached captain-level third class."
"Using this device, she could achieve Bankai early and elevate her Reiatsu to third class."
"What do you think?"
Gin opened his eyes fully, studying Kisuke.
Clearly, Kisuke had recognized how much he valued Rangiku.
After a long moment, Gin nodded.
"Agreed."
"Tessai, please retrieve the Tenshintai from storage."
Seeing Gin's agreement, Kisuke immediately instructed Tessai.
"Understood."
Whoosh-
Tessai vanished, reappearing in under a minute with a human-shaped wooden target attached to his waist.
"This is the Tenshintai."
"Lieutenant Matsumoto, will you use it here or after returning to Seireitei?"
Rangiku looked uncertainly between Gin and Kyoya.
Bankai Training was no small matter.
Having reached [Great Swordsman] level in swordsmanship, Rangiku's combat ability already approached Captain-level.
The only thing holding her back from Bankai was Haineko's inability to fully materialize without sufficient Reiatsu.
Once her Reiatsu reached 3rd-Class, she could assist Haineko's manifestation naturally.
The Tenshintai could bypass this requirement, advancing her Bankai Training by decades.
Neither Gin nor Kyoya would let her refuse such an opportunity.
"We'll do it here," Gin declared after scanning their surroundings.
While he didn't believe Kisuke would dare deceive them, he'd never heard of this device and didn't know how it worked.
Better to use it here where they could address any issues immediately.
Besides, whatever one thought of Kisuke, his scientific prowess was undeniable.
"Very well."
Kisuke nodded, understanding Gin's caution.
"Then let's begin."
Their time in the living world was limited, especially with Isshin unable to return with them.
"However, I must explain one limitation of the Tenshintai first."
Seeing their attention, Kisuke spread his hands, "For me, this wasn't really a limitation."
"And for Lieutenant Matsumoto-" He assessed Rangiku's sharp Reiatsu, "-I believe it shouldn't pose a problem."
"Go on."
"After materializing the Zanpakuto, you must defeat it within three days and make it yield."
"Otherwise, the manifested spirit will run wild."
"The consequences... even I cannot predict."
Rangiku's initial unease vanished upon hearing this.
"Hahaha! Is that all?"
"I just need to defeat my manifested Zanpakuto in three days?"
As Haineko's master, she knew her Zanpakuto's capabilities intimately.
Even before her kenjutsu breakthrough, she could overpower Haineko in their inner world.
Now, even enhanced by the Tenshintai, she remained confident of victory.
Her strength had grown, and with it, her confidence.
If she seemed 'weak', it was only because those around her were monsters.
Leaving Isshin to watch over Masaki, the others moved to a distant flat area.
Kisuke planted the Tenshintai in the ground and stepped back, giving Rangiku space.
"Begin."
Nodding, Rangiku drew her Zanpakuto and plunged it into the Tenshintai.
Boom!
Tremendous Reiatsu erupted from the blade into the device.
Whoosh!
A white spiritual pillar shot skyward, forcing Rangiku back several steps as she shielded her eyes.
"Such pressure..."
Just the initial outburst made breathing difficult.
The gap between 3rd and 4th-Class Reiryoku was vaster than she'd imagined.
Without her unique skills, facing Captain-level opponents would be impossible.
As the dust settled, a girl with cat ears and tail appeared.
Her attire was wild… only her chest and lower body covered by brown fur shorts. Small fangs peeked from her lips, creating a mix of sexy and cute.
"Hahahaha!"
Feeling her enhanced power, Haineko laughed wildly.
"Hey, big-boobed woman! Come on!"
Pointing at Rangiku, she leaned forward like a stalking leopard, "I'm paying back every humiliation you've given me!"
"Oh? Kitty, you're not being cute again."
Rangiku frowned, "You were always so well-behaved before."
Haineko's eye twitched.
With a master like Rangiku, especially after she'd reached Great Swordsman level, resistance was futile.
Under those circumstances, of course she'd been 'well-behaved'.
Did they think Rangiku's sword was decorative?
But now, with her Reiatsu quintupled by the Tenshintai...
If she still couldn't win with such an advantage, then surrendering to help Rangiku achieve Bankai wouldn't be unacceptable!
"Enough talk!"
"Take this!"
Whoosh-
Haineko became an afterimage as she charged towards Rangiku!