Aizen's eyes narrowed slightly, his gaze lingering on the dissipating black haze of the Triple Black Coffin, as he slowly analyzed what he had just witnessed.
"Casting a Hadō of level 90 or above doesn't just demand high Kidō mastery. It also requires massive reserves of Reiatsu."
"If an ordinary Gotei captain tries to cast a Ninety-class Kidō without chanting, it usually won't activate at all. Even if it does, it's already a miracle if it retains just a third of the original power."
His gaze returned to Aiyan, standing calmly in the air, his expression unchanging, as though casting Triple Black Coffin was nothing more than idle recreation.
"But just now... my brother performed not one, not two, but three Black Coffins."
"Without a chant. Without a scratch. Without effort."
"Each one carried two-thirds the power of a fully chanted Kidō No. 90."
"Even if he possesses a Reiatsu exceeding Level 30 Rank—five times greater than someone like Muguruma Kensei—that alone should not be enough to sustain such a feat."
Aizen's thoughts spun rapidly, every piece of the puzzle assembling in his mind.
"...unless he has created something new."
"A fifth technique—one beyond the known forms of Kidō chanting."
"Pseudo-duplication."
"Discarded Chanting."
The moment the term crossed his thoughts, Aizen understood it all.
He had just witnessed a new technique—one that exceeded every Kidō casting method in Soul Society's thousand-year history.
Aizen's lips curled slightly.
"I thought I knew everything about you."
"But once again, you've proven me wrong, brother."
Not long ago, Aizen had perfected his own version of Improved Full Chanting, pushing even the strongest spells to 200% of their base power. He had planned to show it off soon—to surprise Aiyan with it.
He quietly buried the idea.
"If I'd used it, I would've only embarrassed myself."
He couldn't help but laugh inwardly.
Just then, a notification echoed in Aiyan's mind.
[Your Kidō is extremely satisfied after being used in battle. Delighted by the opportunity to 'dance' and defeat the wielder of the strongest water-type Zanpakutō with your new technique, it has rewarded you with a custom Kidō Forbidden Technique: Golden Light Spell.]
Aiyan raised an eyebrow.
He quickly understood its effect.
"This spell combines both. A hybrid Kidō—offense and defense in perfect unity."
He nodded in approval.
"No wonder it's classified as forbidden."
Other Shinigami might spend decades—centuries even—trying to develop original spells.
Even the likes of Kōga, with centuries of Kuchiki heritage and access to ancient Kidō scrolls, had only managed to create a Hadō comparable to Level 80.
Aiyan had only been a Shinigami for a few months.
And already, he had a self-created Kidō technique, a custom forbidden spell, and could cast triple Black Coffin without chanting.
His talent was not just rare.
From behind, Aizen's voice drifted in.
"That was your own casting technique, wasn't it?"
Aiyan turned slightly. His younger brother was floating through the air, eyes gleaming with anticipation.
"Triple Black Coffin—that's not possible without a new Kidō technique. You must've created it."
Aiyan didn't deny it.
"I created it while I was still studying at the Shin'ō Academy."
"...Discarded Chanting."
"Discarded Chanting..."
"Combining the speed of chantless casting with the power retention of double chant and pseudo-duplication..."
"And still retaining power comparable to full incantation... optimized even beyond that."
A soft exhale escaped Aizen's lips.
"It's a technique far beyond the grasp of Soul Society's so-called 'Kidō Masters'..."
"Compared to you, even the highest instructors of the Kidō Corps are still crawling."
His words were laced with genuine admiration—but also something deeper.
"I won't fall behind you, Brother."
He saw the flicker in Aizen's eyes—the determination. The silent challenge.
"Then I won't teach it to you."
"You wouldn't accept it anyway."
"You'd rather bleed for a thousand years than learn it from someone else."
Aizen didn't respond, but the amused twitch at the corner of his mouth said enough.
That was exactly right.
A voice rasped from the shadows.
It was low. Guttural. Choked with blood and hatred.
His four limbs were gone, reduced to mist.
His body was mangled and twisted.
And yet—his head remained.
His voice crawled from his throat like a curse.
Aiyan's brow lifted in mild surprise.
"Still breathing after all that?"
He approached calmly, hands folded behind his back, watching as Ginrei's blood pooled beneath him.
"Triple Black Coffin, each cast holding two-thirds the full power."
"That much force should've turned your soul into vapor."
"Yet you're still clinging to life."
"Even I underestimated you."
Ginrei's mouth twitched.
His yellow, Hollowed eyes burned with an almost feral resentment.
Aiyan looked down at him—not with contempt, but curiosity.
"You endured one of the deadliest Kidō combinations ever cast. Four limbs obliterated. Reiatsu twisted beyond recognition."
He reached out and lightly tapped Ginrei's forehead.
Tōsen Kaname, watching from behind, swallowed audibly.
The silence in the ruined Palace of Repentance was deafening.
Even the spiritual currents in the air seemed to pause in reverence—or fear.
Aiyan stood up straight, the silence heavy around him.
"You won't survive the next one."
He didn't say it as a threat.
He said it like a doctor giving a prognosis.
Like a scientist observing the final stage of an experiment.
Aizen approached silently.
He looked at what was left of the once-proud Captain of the 6th Division—the Kuchiki family's pillar.
And then to his brother.
The one who had reduced him to this state.
And yet—this wasn't the end.
It was the beginning of something even greater.
The boundaries of the Shinigami race were beginning to crack.
Was the one holding the chisel.