Sekai no Tengoku.
That was the name of Keiji's zanpakutō.
The blade shimmered as he spoke the words, the sound ringing like a bell. Right after, the air around him seemed to bend, as if an invisible force were pulling everything inward. The particles of Reishi (Spirit Particles) vibrated violently, rising into the air like dust being sucked into a vortex.
Keiji felt the thrill rush through every part of his body. His heart pounded hard, and the crooked smile that formed on his lips couldn't be contained.
Sora vibrated with the same excitement.
{That's it, Keiji! Show her! Show all those spectators! This is the power of "Heaven"!}
From the very beginning, Keiji and Sora weren't just partners. They understood each other instinctively, almost as if they'd been born together. The spirit of the zanpakutō and its wielder blurred into a single voice.
They were one and the same.
And like every shikai, Sekai no Tengoku manifested its own unique ability when released.
The ability to connect with, manipulate, and absorb the reishi of the "Heaven."
And in the Soul Society, "Heaven" was everywhere.
The paved stone streets, the twisted trees of the Rukongai, the calm rivers, the walls of the Seireitei, even the clouds floating above — everything was made of reishi. That was the raw material, the foundation of absolutely everything in that world.
Its only limitation came from what had already developed a will of its own, that is, anything that had formed a "soul". The body of a Shinigami, the essence of a Hollow, the life of an ordinary spirit… all those were beyond its reach.
But everything else was the personal feast of Sekai no Tengoku.
A power truly capable of destroying the world.
Unohana watched with shining eyes, her lips curving into a wide smile.
"A power like that… it's not an exaggeration to say you could destroy the Soul Society itself if you wanted."
Her tone was serene, but there was a spark of excitement in her voice, as if those words were a genuine compliment.
It was the second time she had seen that power in action, and even now, its weight made her tremble. Because it was like facing the sky itself as an enemy.
But for someone like Unohana, what she felt wasn't fear; it was desire. The desire to test herself, to measure her blade against something that could truly shatter the natural order.
Keiji twirled his sword lightly, the crooked grin on his lips growing wider.
"Maybe… but that's not really my style."
The ground around them began to distort as the reishi was drawn into his released zanpakutō. The small stones crumbled into dust, the wooden walls of nearby houses cracked as if about to splinter, and even the wind seemed to lose its strength, pulled toward the blade.
The battlefield now responded directly to the presence of Keiji's shikai.
Unohana took a firm step forward, adjusting her stance. The serene smile that fooled everyone was now being eaten away by raw excitement.
"Then show me."
She raised her nodachi, the blade reflecting the energy that pulsed in the air.
"Show me just how far the 'Heaven' can expand."
Sekai no Tengoku wasn't just a powerful shikai. It was a monstrous engine that fueled Keiji from the inside out.
Every particle of reishi absorbed was pulled directly into his body, reinforcing the spiritual structure that made him. The body of a shinigami was made of condensed reishi; their reiryoku was the energy born from that existence. And Keiji, with every second that he kept his shikai active, pushed that energy to insane levels.
The flow was continuous like a river that never ran dry. As long as Sekai no Tengoku remained released, Keiji's only limit was the capacity of his own soul.
And that was exactly what fed his confidence to face all the Captains.
With every surge of Keiji's reiatsu, Unohana's smile widened, revealing the beast hiding beneath the healer's skin.
"Exactly what I expected from you, Keiji-kun. You're a man who can satisfy me!"
Keiji raised his sword, his entire body humming with energy.
"This is the first time I've used my shikai in a real fight, so let's make the most of it~"
They charged at the same time.
The initial impact was brutal. The ground shook, the street stones shattered into fragments, and the air grew thin, as if it had been stolen from the space between them. The sound of their blades colliding echoed like repeated thunderclaps.
Sparks flew with every clash. The metallic ringing of steel filled the empty district, mixing with the distant echo of reishi being devoured by Sekai no Tengoku.
Their blades struck once, twice, ten times in succession... each collision sounding like thunder. The cuts traced lines through the air, almost invisible, and the repeated impact made the ground tremble.
Unohana attacked with deadly precision, mixing strikes and feints to try to slip through Keiji's increasingly sharp defense. He blocked and countered with laughter, moving his body naturally, using his constantly rising reiryoku to keep up with her speed and strength.
But the difference soon began to show.
In essence, considering only reiryoku and reiatsu, there wasn't much separating Unohana and Keiji. She could still handle him because of her mastery of countless kendo styles and her vast experience.
But once the balance of power tipped, that advantage began to fade.
Each time Unohana stepped back to launch another attack, Keiji responded faster and harder than before.
He blocked a cut that would've torn through his shoulder, spun his body, and countered with a heavy strike. Unohana dodged smoothly, but she noticed a tiny delay in her movement, one that hadn't been there before.
"Excellent! Keep going, Keiji-kun!"
She showed a wide, almost sickly grin.
Keiji's smile was equally far from his usual idle demeanor. He was hurt, bleeding from smaller cuts that Unohana had already carved into his skin, but with every drop of blood, he seemed more alive.
Unohana didn't hide anything either, her expression made it clear how much pure joy she felt.
"Don't disappoint me, Keiji-kun! Show me everything!"
They charged again, one shunpo against the other. The sound of their movement came just before the collision, their blades slicing through space in nearly invisible paths.
The district around them could no longer withstand the pressure; it began to crumble. Walls disintegrated into dust as reishi was drained away, rooftops split apart from stray shockwaves, and the entire ground looked ready to collapse.
And still, neither of them showed the slightest sign of backing down.
The sound of reishi being devoured by Sekai no Tengoku grew louder, like a silent roar swallowing the entire district. Every particle absorbed made Keiji's reiatsu swell even more, until the air around him vibrated like stretched strings on the verge of snapping.
Keiji advanced, his feet gliding across the ground in smooth steps, each strike coming from a different angle, testing the once-perfect guard of Unohana. He twisted his wrist, mixing direct thrusts, wide horizontal cuts, and diagonal slashes that crossed like a web, almost as if he were performing a live demonstration of the entire zanjutsu manual.
Unohana responded like a river in constant motion. Her nodachi flowed in circular motions, parrying, deflecting, and redirecting. It was as if her blade had turned liquid, reshaping itself with every defense. Yet, even so, the rhythm began to slip from her control. First, a shallow graze on her arm. Then a thin red line across her shoulder. Soon after, a deeper cut on her hip that forced her to retreat half a step.
But Unohana wasn't displeased. Every wound only made her smile wider, her eyes gleaming brighter.
Keiji paused for a moment, spinning his sword in the air and feeling his reiatsu surge. Sekai no Tengoku kept pulling in reishi from the surroundings, pushing his reiatsu to the upper limit of a Spiritual Class 2.
The air around him shook, too heavy for any nearby soul in the district to withstand.
He placed a hand over his chest and redirected the reishi Sora had gathered to cast Kaidō. A green light glowed over his body, closing his wounds and stopping the bleeding with incredible speed.
Unohana raised an eyebrow before smiling even wider.
"So that's why… Keiji-kun also learned the art of Kaidō for the same reason I did."
Unohana had originally mastered Kaidō to prolong her battles; long before she ever became Captain of the Fourth Division.
Placing her palm over her own chest, she channeled reiryoku and began to heal her injuries as if nothing had happened. The blood stopped flowing, and when she lifted her head again, she looked completely untouched.
The two of them stood facing each other in the middle of the ruined district. The ground around them was nothing but rubble, yet they acted as if none of it mattered.
"Do you have anything else to show me, Keiji-kun?"
Unohana asked in a soft and sweet voice... yet one thick with excitement.
She could feel, more than she knew, that there was still more for her to enjoy in this fight.
Keiji chuckled, tilting his head slightly.
"Thinking about using your Bankai? I don't mind if you try, Captain."
It was practically a provocation. Keiji was saying, outright, that he could handle Unohana even if she used her Bankai.
Unohana closed her eyes for a moment, then opened them with a daring smile.
"It's not good to be that confident, you know? I'll decide for myself whether I need to use my Bankai."
Keiji narrowed his eyes, amused.
"Is that so? Then let me try something first."
Unohana's brows lifted in anticipation, but then she noticed the change.
The suffocating reiatsu that had been pressing down on the entire district suddenly shifted. It didn't disappear, but it became… light.
Yes… it was like the breeze that drifts on a sunny day.
And then, as the two of them locked eyes, Keiji took one step forward... and vanished.
Unohana's heart skipped a beat, but when she tried to react, it was already too late.
He appeared behind her in the blink of an eye, his sword piercing through her back and emerging right along the scar that ran between her chest and collarbone.
The sound of steel cutting through flesh echoed across the ruined district.
Unohana's eyes widened. A smile spread across her face as blood trickled down her lips.
"This… yes… this is what I long for~"
She murmured, her voice dripping with almost indecent excitement.
Even with Keiji's blade buried in her chest, she twisted her nodachi in a counterattack, but in the next instant, Keiji was no longer there. He was in front of her again, sword in hand, as if the distance between them had vanished in a flash.
Unohana focused every sense she had on his blade, trying to predict the next strike. But what came was an impact so sudden she barely had time to react. Her defense responded purely out of instinct, a reflex born of centuries of combat.
She retreated with a quick shunpo, her feet landing lightly despite the dirt and blood staining her skin and face. The metallic taste of blood lingered in her mouth, but she ignored it, wiping it away with the back of her hand. The gleam in her eyes only grew stronger.
"He actually… disappeared."
No reiatsu could ever be fully suppressed. Every shinigami had tiny openings on their wrists that constantly released their reiatsu. If these were blocked, the shinigami in question would be incinerated by their own internal reiatsu.
And yet... she couldn't feel Keiji's presence at all.
It was only thanks to a thousand years of experience that Unohana finally understood.
There were no traces on Keiji's body. No flicker of killing intent for her to track. He simply moved, and when he did, he became invisible to the battle instinct that an experienced swordswoman like her had sharpened through thousands of fights.
Keiji's reiatsu wasn't a crushing pressure trying to overwhelm her. It had become the "Heaven" itself, invisible precisely because it was everywhere.
No one notices the air they breathe or the weight of the sky above their head. In the same way, Keiji hid himself within the natural order, vanishing from conscious perception.
Unohana's eyes widened further, her expression breaking into something raw and almost feral. A low laugh escaped her lips like an intimate whisper, heavy with an excitement she could no longer contain.
"Magnificent…"
A sound far too improper slipped from her throat, as if it were impossible to restrain the euphoria bubbling inside her chest. In a thousand years, no one had ever made her feel this way.
Her body trembled with pure ecstasy.
Finally she stood before a truly worthy opponent, someone who could make her use every ounce of her strength and remind her of the thrill of battle.
And so, she raised her nodachi with steady hands.
"Bankai."
The word echoed like a decree.
Unohana's left hand slid along the edge of Minazuki, and the blade transformed into a thick, viscous, dark-red substance that looked like blood. That same blood-like liquid poured from above her in torrents, enough to form a massive pool and flood the entire battlefield.
"Minazuki."
The district — already shattered from their earlier clashes — was swallowed by a new darkness. The blood spread like an ocean, covering the streets and reflecting the light in crimson hues, turning everything into a grotesque scene.
Unohana smiled, her lips stained red.
"The game's over. Prepare yourself."