High-level Hadō numbered from 61 to 90 were already considered extremely advanced, and Hadō #90—Kurohitsugi—had long been recognized as a spell that sat on the very edge of forbidden Kidō.
Hadō #91—Senjū Kōten Taihō—was outright forbidden; while a single blast didn't exceed the destructive compression of Kurohitsugi, the overlapping barrage inflicted even greater total damage.
Yet, when the flames and smoke finally cleared, Genryūsai Shigekuni Yamamoto stood unharmed.
The inferno surrounding his body swelled outward, forming a dense, fiery barrier.
Yamamoto swung Ryūjin Jakka, releasing a blazing crescent of fire toward Kurotsuki Renya.
BOOM.
A transparent wall materialized instantly before Renya—
Bakudō #81: Dankū—
blocking the flames before they dissipated.
"You can use Dankū and Kurohitsugi without incantations—and even forbidden spells. Your Kidō talent is formidable," Yamamoto said calmly. "But it is still not enough. Let us begin the real engagement."
Renya picked up his Zanpakutō, inhaling slowly.
"Descend—Tenraimaru."
Dark clouds swirled above the endless sky of Muken. Lightning flashed violently before a thunderbolt struck Renya's outstretched hand, shaping itself into a short spear crackling with electricity.
"This is your release ability?"
Yamamoto sounded genuinely impressed.
"To alter the atmosphere within Muken with only a Shikai… remarkable."
Renya smiled lightly. "Captain—please enlighten me."
The true battle began.
Renya tightened his grip on Tenraimaru. His spiritual pressure converted into pure thunder, condensing into a pair of lightning-forged wings that spread behind him.
With a single flicker—
SHWIP.
Renya vanished.
He reappeared behind Yamamoto in an instant, thrusting his spear.
"Ennetsu Jigoku."
Unable to match Renya's speed, Yamamoto triggered a massive defensive eruption.
A vast globe of fire exploded outward from his body, engulfing the arena and swallowing Renya whole.
But within the inferno, Renya's body gleamed with blue reiryoku—
a thunder-formed barrier shielding him.
His spear pierced through the flames and shot forward again.
This time Yamamoto reacted, swinging Ryūjin Jakka horizontally, blocking Tenraimaru.
At the same instant, Renya aligned the spear tip with Yamamoto's chest. Lightning flashed—
—and a full-powered thunder cannon fired.
Unlike the non-incanted version of Hiryū Gekizoku Shinten Raihō, this one was equivalent in force to the fully-chanted Hadō #88.
BOOOOM.
The thunder beam enveloped Yamamoto—
—but once again, Dankū appeared.
"Bakudō #81: Dankū."
Yamamoto could perform forbidden techniques and high-level Bakudō with ease.
Without chanting, the wall wouldn't fully stop the blast—
but it bought him enough time to step back and counter.
A single slash discharged a towering pillar of fire—
obliterating the thunder cannon and racing toward Renya.
But he had already moved.
Renya appeared behind the Captain Commander once more, thrusting.
"I expected you behind me."
Yamamoto rotated instantly, their weapons clashing with explosive force.
Thunder and flame collided, filling the chamber with red and blue light.
Renya didn't fire another thunder cannon.
He twisted Tenraimaru upward, knocking Yamamoto's blade aside.
What is he planning?
Yamamoto caught a flicker of motion—
and flashed aside.
SHOOM.
A high-velocity streak tore past him.
It didn't hit directly, but the sheer kinetic energy shredded the flesh along his waist, carving a deep blood-opening wound.
"An electromagnetic round… a full-force variant. Four-kilogram projectile. Enough power to pierce through solid mountains."
Yamamoto exhaled.
"…Impressive. You've managed to wound me. Then I will respond in full."
He raised Ryūjin Jakka.
"Ennetsu Jigoku."
Flame pillars erupted skyward—dozens—shifting unpredictably across Muken like living towers of fire.
Renya dodged with lightning-fast movement—
—but only for a moment.
Every pillar suddenly detonated simultaneously.
BOOOOOOOOM.
Muken became a world of fire.
Temperatures skyrocketed.
Everything scorched.
Then—instantly—
the flames vanished.
Yamamoto drew them back into Ryūjin Jakka.
Behind him stood Renya, lightning wings spread, Tenraimaru pressed directly against Yamamoto's back—
its tip already piercing skin, centimeters from his heart.
As the last flame disappeared, Renya withdrew the spear respectfully.
"Captain… thank you for the lesson."
Yamamoto exhaled, defeated.
"I've lost. I cannot match your speed."
He glanced at Renya.
"With such strength, no current Captain could defeat you. But it is still not enough. If I were to release my Bankai, you would not even be able to approach me."
He was referring to one form of Zanka no Tachi—
Zanka no Tachi, West: Zanjitsu Gokui,
where his spiritual pressure becomes heat exceeding 150 million degrees.
Anything that approached would disintegrate instantly.
Renya's speed, as he was now, could not overcome that.
But Renya replied lightly:
"Captain… I haven't even used my Bankai yet. I doubt my Bankai could defeat you outright, but I certainly could force a mutual destruction."
"Bankai…?"
Yamamoto straightened.
"If you have mastered Bankai, then defeating me may truly be possible."
He continued:
"Even without Bankai, if you had chosen to conceal your abilities earlier, you could have launched a surprise attack and killed me. And just now—you could have driven your attack home, yet you stopped. I misjudged your intentions."
Yamamoto had withheld Zanka no Tachi not only to test Renya's strength—
but to test his heart.
Renya smiled.
"From your perspective, Captain, it was right to be cautious."
Yamamoto nodded.
"Very well. Then I shall support your plan. Come—let us return."
He stepped forward, but staggered slightly.
Blood pooled from the wound in his abdomen, far more severe than the one in his back.
Renya rushed to help him, but Yamamoto dismissed him with a glare.
"I can still walk."
Together, they reached the door of Muken.
Renya slid it open.
Outside waited Unohana Retsu, watching calmly.
"Have you two decided the winner?" she asked.
"I lost," Yamamoto answered bluntly.
Renya immediately added,
"Only because the Captain held back. Had he fought seriously from the start, I would be dead."
"Even so," Unohana replied softly,
"your achievement is remarkable."
She turned to the Captain Commander.
"Allow me to heal you before you proceed."
Yamamoto accepted the treatment.
Once the bleeding stopped, he opened his eyes and addressed Renya:
"Let's go. Tell me—how do we kill Aizen?"