"Muramasa... among all the illusion-type Zanpakutō I've seen in my life, it is the strongest—without question."
"Whether it's elemental-type, Kidō-type, or even the most aggressive close-range Zanpakutō, none of them can resist the hypnosis cast by Muramasa."
"But among them, there is only one Zanpakutō completely immune to Muramasa's ability. The only exception—"
Kuchiki Ginrei's eyes narrowed as he stared directly at Aizen Sōsuke.
"Hah…! So Kyōka Suigetsu isn't a flowing-water type at all. It's an illusion-type Zanpakutō... and not just any illusion-type—"
"It's the strongest."
"Only that explains it all."
He drew in a deep breath. Even for someone of his composure, his expression betrayed true shock.
"As expected of the Sixth Division's current captain... the one who brought the Kuchiki clan back to the peak of nobility in this generation."
"It seems the Kuchiki clan's archives really have preserved more than the world knows."
"For countless centuries, you've recorded every known Zanpakutō's name, attributes, and powers, haven't you?"
Aizen responded with a slight nod and a soft smile.
Not only did he confirm Ginrei's statement, but in that single look, he also offered a rare gesture of praise.
"And what about you, Aiyan?"
"Now that the truth is exposed, there's no point hiding it."
"Aizen's Kyōka Suigetsu is the apex of illusion. But your Zanpakutō—Kōfūin—what type is it?"
Ginrei turned his attention from the younger brother to the elder.
Aiyan simply replied with a calm tone.
"If that's your guess..."
"Then let me confirm it."
"Kōfūin—Zanpakutō of light and darkness. The strongest dual-elemental Zanpakutō."
"...A dual-type... and both light and darkness... the strongest in each domain?"
Ginrei's pupils shrink. His jaw clenched.
Even as the Kuchiki patriarch, whose knowledge of Soul Society's history rivaled anyone alive, even he hadn't heard of such a thing.
In the endless cycles of history, twin Zanpakutō had emerged—rare, powerful—but even they came in pairs.
Not a single blade holding two supreme attributes.
"That's right."
Aiyan's tone remained casual, as if speaking about the weather.
"A gift, in return for your... invaluable contribution to our Hollow experiment, Captain Ginrei."
His words, slow and deliberate, were like knives in Ginrei's chest.
Aizen added with a hint of amusement:
"My elder brother holds the strongest dual-elemental Zanpakutō in all of Soul Society."
"I hold Kyōka Suigetsu—supreme illusion-type."
Kuchiki Ginrei muttered something under his breath—barely audible.
And then it hit him.
"Wait... Hollow experiment?"
His voice suddenly turned sharp.
He raised a trembling hand to his face. The place where Tōsen Kaname's blade had pierced him now pulsed with an eerie sensation.
"Hollow... you... you dared to use Hollowfication... on me!?"
The old noble's eyes widened in horror.
Shock. Anger.
His voice cracked under the weight of rage.
He had spent the last few moments trying to understand their scheme—testing, delaying, stalling for answers.
But now something deep within his body stirred—a volatile force, foreign yet horrifyingly familiar
It wasn't just pain. It was like a new Reiatsu, one completely opposed to his own, was clawing its way out from inside.
A Hollow's essence.
"Why else do you think we're here?" Aiyan answered with a faint smile.
"Why else would I bother telling you about Kōfūin?"
"Captain Ginrei, you should feel proud."
"You're the first Shinigami—aside from Aizen—who's witnessed the full truth about my Zanpakutō. That alone puts you above most in Soul Society."
"Besides, you're not a victim. You're the final stage of our experiment."
"We weren't stalling, Captain... we were just waiting for your Hollowfication to mature."
As the weight of Aiyan's words sank in, Aizen's gaze was fixed solely on Ginrei's body, watching closely.
The spiritual fluctuations.
The fusion—or resistance—between Shinigami and Hollow spiritual pressure.
Every change was a data point.
"I am the patriarch of the Kuchiki clan..."
"A noble of royal blood... Do you have any idea how insane your actions are?"
"Tainting the nobility with Hollow?"
"Even a Gotei captain would never escape judgment for this!"
His voice cracked with both fury and desperation.
But the moment he tried to calm himself—
Boom.
The Hollow Reiatsu inside him flared violently, threatening to erupt.
Ginrei staggered, using Wanchuan Kaikai as a cane, forcing his Reiatsu to push back the invading force. But the effort was enormous. Sweat drenched his brow.
"Interesting..." Aizen muttered.
"I've used dozens of prisoners from the Repentance Palace—once proud Shinigami. But none of them survived more than seconds into Hollowfication."
"They either exploded into spiritual dust... or dissolved into nothing."
"But you—"
"You suppressed it."
"You resisted it."
"And your Reiatsu is... increasing?"
"Is it the absurd spiritual density of a Gotei captain?"
"Or perhaps... is it your 'noble bloodline' that gives you this edge?"
Kuchiki Ginrei didn't reply—his breathing ragged, his hand trembling against the hilt of his blade.
But Aizen wasn't done.
"Why you, you ask?"
"You chose us, Captain Ginrei."
Aiyan's voice dropped to a calm chill.
"You made that choice... long ago."
At those words, Ginrei's eyes widened again.
And then...
He remembered.
His pupils constricted, his breathing hitched.
Aiyan smiled.
"You remember now."
"The attack on two first-year students in the Shin'ō Academy dormitories..."
"A minor incident, dismissed by the Kuchiki clan."
"But I remembered. I remembered it well."
Aiyan stepped forward, his voice sharp with each syllable.
"Hirako Shinji was humiliated in a public spar by me—and lost everything overnight."
"And then, in our dormitory..."
"You sent an assassin."
"You tried to kill me. And my brother."
"Tell me, Captain Ginrei... did you really think I'd forget?"
"You struck first. We're just finishing what you started."
"Kōga? Dead."
"Muramasa? Seized."
"You?"
Aiyan's smile grew sharper.
"You are our most perfect specimen yet."
"And believe me... this is only the beginning."