Aizen's eyelids slid open to the first hesitant fingers of dawn creeping in through the rice paper windows, illuminating the room in a rose and amber wash. The Squad Four barracks, normally heavy with the tang of antiseptic and the muffled hum of healers, were now heavy with the silence of the temple at dawn. He let himself remain still for a fleeting, golden instant. Retsu Unohana's body nestled into his side, the slow, even rhythm of her breathing tracing the skin of his shoulder. Behind the stillness of the moment, though, lay an undertow thunder—a new, throbbing vibration humming but just past the rim of his soul.
This was beyond comparison to anything he had previously known, even at the height of his ascension with the Mirror God. It was more than a rush of strength, but instead the wholesale remaking of his spiritual composition. His Reiatsu, once cold and stifling like frozen steel, had become fluid—liquid. It flowed through him like a secondary pulse, uncontrolled but precise, timeless but fresh. His every gram of flesh hummed with raw potential, like the very atoms of the air bending to him in respect. He felt, in the surety of root alteration, that anything short of evolution would be to say.
He stood up slowly, careful to appease the woman whose sword had long ago shed the blood of god and monster both. Aizen let go of the blanket. The silk slipped away from his body like water, and the dawn revealed the subtle sheen dancing upon his body. It was not brightness, but the sheen of his power—Reiryoku unbound by the strictures of classical Shinigami training. No longer contained within a frame. No longer restricted. The power within him had grown like Ki, but more intangible, more cosmic, as if resonant with the underlying mechanisms of existence itself.
He extended his own hand, fingers spread in careless ease, and willed. No incantation, no ritual of intricate movements. Just will. One questioning, straining flick of mind. A spark developed at the end of his fingers, aglow with tongues of stuttering white lightning. It blazed out in the velocity of divine wrath and hit a porcelain vase in the corner of the room. The object shattered to dust in an instant, the only noise a whispery pop as the displaced air rushed away. Its success pleased him—not for the damage itself, but for how extremely natural it had been. No effort had been required of him, no push and pull. Just instinct.
She followed after him. Her eyelids opened, pupils focusing slowly in the dim light, only to widen slightly as they registered the altered environment. She did not respond to the ruin, or to the electric light. Her gaze shifted instead to him with the same silent, deadly intensity she alone could muster. A very slight smile crossed her mouth, though one tinged with curiosity and perhaps fear.
"Aizen," she whispered, her voice drowsy with sleep and wonder. "What's changed?"
He approached her, his eyes focusing on hers—the face of the first true monster the Soul Society ever created. He stepped closer, the hem of his robe flowing about him like mist. His Reiatsu coursed through the space like ocean waves, massive but firmly contained. And when he did speak, he did so confidently.
"I've transcended." He stated it without arrogance in his tone, just fact. "Our bond has functioned as a catalyst, releasing a degree of potential I'd previously only had glimpsings of. This power in me… no longer operates under the laws of Kido or Zanpakuto arts. It moves of its own accord, driven by purpose instead of form. It's as though the barriers that used to govern spiritual energy have collapsed."
Unohana sat up, linens slipping off her shoulders. Nor did she shoot him a fleeting glance when she looked into his eyes, nor shrink away in reaction to the power of his changed aura. If anything, there was respect in the moment of silence between them, mutual understanding between two beings long since moved out of the league of the ordinary Shinigami. She grasped his hand, and he let her, her fingers entangling his.
"The Soul Society," she breathed, "has always been afraid of that which cannot be categorized. What you share with me. it would terrify them."
Aizen's head canted. "And they would have cause to fear." There was nothing of evil in his tone, only inevitability. "But I do not desire their fear. Not yet." He stood still, examining her face as one would examine the facets of a valuable gem. "There is more to this than power, Retsu. I sense it—the threads of causality warping, the realms shifting in ways they never have before. As though the world itself held its breath in anticipation of what I am becoming."
She exhaled quietly, her fingers tightening on his. "Then tell me, what is it you intend to do with the power?"
Aizen did not react immediately. He considered telling her everything—his covertly planned scheme, the subversion of Central 46's power, the ultimate reorganization of the very fabric of reality in accordance with something superior. He saw in her the remnants of the healer, the last traces of the being who still believed in balance, even if achieved through blood. She was not ready. Not yet.
"For the moment," he breathed softly, his smile as enigmatic as ever, "we sleep." She blinked at the reaction, but he could see the grateful part of her—grateful that she could still have tomorrow written in anything but flames. He lay down next to her again, the hum of power still coiled along his skin, but calmed by the heat of her body curled up against his. Even gods needed to sleep, he thought.
**
The sun had risen to its peak, bathing the tiled roofs of Seireitei in the golden, warm glow. With it, the quiet hum of life in the whitewashed barracks began to awaken—the muffled tread of the patrols, the distant rumble of the training cries, the soft hiss of papers in the hands of anxious lieutenants in preparation for morning report. Aizen stood in the quiet of the private quarters of Squad Four, at the window as the light streamed across the wood floorboards in long, slanted lines. He felt the pressure of time against his skin, a pushing presence from the world beyond the quiet of Unohana's bed.
Although he would have preferred to remain longer, wrapped in the silent introspection that could only come from such intimate change, he knew absence led to questions. With the Gotei 13, suspicion was cloaked in ritual; being absent too long, and without reason, risked stirring the kind of scrutiny he was not yet ready to provoke. With restraint, Aizen stepped back from Unohana's bedside, her tranquil form folded beneath purple drapings. The scent of jasmine still clung to the faint sheen of her skin, a sensory anchor he nearly allowed to pull him back.
He wore his uniform with practiced aplomb. Each fold of it dropped across him like a shield—not a protective shield against swords or Hollow's claws, but suspicion. He walked with precision, folding his haori like one who knew too well how quickly illusions broke. By the time he pushed the door open and strode into the hall, there was no longer any outward indication of the power that churned just beneath his skin, or of the nearness that had roused it up.
At the center of the courtyard stood Hinamori Momo, feet splayed wide, her face protective but relaxed, her eyes shining with restrained worry. Aizen observed it in the slight rigidity of her shoulders, in the way her hands were folded in front of her instead of hanging loose at her sides. She smiled when she caught sight of him, the smile hesitant but genuine.
"Good morning, Captain Aizen," she said, bowing slightly.
He smiled at her, warmly and kindly. "Good morning, Lieutenant Hinamori. Did you sleep well?"
She nodded, but for a moment there was a flicker of uncertainty in her eyes. "Yes, sir. I... I was worried last night when you didn't return by dark."
"I had to speak to Captain Unohana about some... health concerns in private," he stated matter-of-factly, his voice a soothing balm of explanation. "You needn't be concerned. Thank you for your understanding."
Her shoulders eased significantly, and her eyes softened. "I see. As long as you're all right."
They had breakfast beneath the blooming sakura trees, the meal plain: miso soup, steaming hot rice, pickled vegetables, and grilled salmon sliced thin. The food was tasteless after the banquets he had savored in the royal kingdom when he had ventured into the higher spiritual realms, but Aizen was reassured by the familiarity. He allowed Momo's chattering to fill the gap between her and him, her accounts of Kira's new fighting technique, Renji's incessant arrogance at a meeting with Captain Kuchiki, and of the small garden she had begun to work on in the rear courtyard. Her voice contained the naivety of a child born of war, anxiously sewing peace into whatever fertile ground lay at hand.
As she talked, Aizen watched her—not with his eyes, but with his mind. She was the same. Her light as a soul remained as intense and unyielding as ever, burning with an adoration so complete it might one day blind her. And in that, she was perfect. Not as a pawn—he had abandoned such straightforward thinking many years ago—but as a constant. A light in the storm of what he was becoming.
As the meal was done and the plates piled into a wooden platter to her side, Aizen stood up with his hands clasped behind him, gazing out towards the treeline at the edge of the barracks.
"I'll be out of pocket for the remainder of the day," he said, not turning to face her. "I have some personal matters I must attend to. Would you see my appointments are rescheduled, and that no one attempts to seek me out?"
"Yes, Captain," she answered, standing up straight, the tray balanced in her hands. "Is... is everything all right?"
He stood before her, and his smile was soft but fiercely intent. "All is well. At times a man must pull back into solitude in order to truly listen to what the universe is trying to tell him. This is such a time."
She blinked and nodded, obviously comforted by the assurance in his voice. "Alright. I'll inform the team."
He reached out and placed a hand on her shoulder, his gaze holding hers. "You've gotten stronger, Momo. I can feel it. Continue along that line. Your growth isn't just a benefit to this division—but to me, on a personal level."
Her eyes shone with emotion at the compliment, her voice barely above a whisper. "I won't let you down."
"I know you won't," he said, withdrawing his hand.
And with that, Aizen turned and strode towards the edge of the courtyard, white haori billowing behind him like a banner. Beyond the path lay camphor trees and blooming azaleas, a road few Shinigami traversed without cause. Passing through the outer gates, the spiritual clamor of Seireitei dropped from his ears, and in its place was the heavy, throbbing beat of the natural world. The forest beyond Squad Five barracks was dense, interwoven with old paths and spiritual scars from training grounds abandoned long ago.
Outside of Shinigami patrol range, hidden deep within the woods where even the Onmitsukidō sentinels had not ventured, Aizen halted. He stood still in the silence, his eyes closing as he drew in a slow, deep breath, savoring the quiet. The air was cold here—clean and sharp, scented with the promise of moss and of old bark. It grounded him in a way nothing else could, anchoring his otherwise unanchored sense of time. At his feet, he could feel it—the slow beat of existence, the pulse of the world that beat unseen beneath the surface of Seireitei. It was the pulse of time itself. Even gods, he believed, would not be able to escape it forever.
Running his fingers down the chest of his uniform, Aizen dipped into the center of himself. Not just his Reiatsu, but further—his Kagami no Kami, the one now slumbering inside him like a coiled dragon. With a movement as elegant as it was sharp-edged, he tore the fabric of space—not with strength, but with understanding. Like a master who opens a door long sealed, he split a glistening tear in space that rippled like disturbed water, and out of it sprang a tall, silvered mirror, unmoving and non-reflective.
This was not an ordinary gateway. This was a metaphysical gate, a portal that existed from the very essence of his Zanpakutō's adult form. The mirror was not of this world, but of Kōchū Kagami no Rekisho—the Infinite Reflecting Archive of History, a subdimension forged by Kagami no Kami itself. Aizen had constructed it not of Kido or rock, but of intent, foresight, and a dash of divine arrogance. It was a realm that served no one but him.
He passed through without blenching.
The forest that lay behind him vanished in a moment, engulfed by the wave of light. In its place was an endless sea of glass—mirror planes that stretched out in all directions, folding endlessly in on themselves like a fractal. The air radiated an unearthly iridescence, a light that seemed to warp reality at a thousand impossible bends. All surfaces reflected Aizen not only as he was standing, but as he had stood, as he would stand to stand, and as he could never stand. It was a prison of paradoxes, and to him, home.
"Kōchū Kagami no Rekisho…," he muttered to himself, allowing the title to swirl around in his mouth like scripture.
Here, he passed undetected. Unstopped. Here, he could experiment and experiment without fear of interference from Captains or inquisitive gazes in the Central 46. Not even the Spirit King himself, omniscient as he was meant to be, could peer into this world without first understanding how it had been created. And that, Aizen thought with a faint smile, was something that was not known to anyone but himself and the deity in his sword.
He raised one hand.
The earth beneath him began to ripple, the glass curving as if it were composed of memory. From the depths rose a twisted substance—black as tar, glinting like starlight, a liquid mixture of shadow and hunger. It began to climb up his arm like a snake, speaking softly in a language that vibrated in his bones.
This was not normal spiritual energy. This was Hollow essence—raw, unadulterated, distilled from the nothingness beyond the edge of soul and form. It possessed no voice, was a thing without will, and yet it moved with intent. Aizen felt it encircling his wrist, curling around it like a long-lost lover.
"It's beautiful," he breathed, half to himself. "Such naked randomness. Such wild promise. No thought. No restraint."
The Hollow essence throbbed with energy in reaction, not unlike a pulse, as if in acceptance of his words. It was the soulstuff of Gillians and Vasto Lordes, the same energy that had caused his body to warp before when it was merged with the Hōgyoku. But now, it was not overwhelming him. He was not succumbing to it. He was mastering it.
He stood still, completely still, his position open, near-imperial, as the Hollow power enfolded his arm like smoke around flame. He didn't say a word, didn't even move his hand—instead, he just allowed his form to be a vessel, the raw power settling into his spirit with silent precision. The mirror surfaces above and below him undulated gently, inscribed momentarily with elder glyphs—glyphs not drawn by Kido, but by beings as old as the Great Noble Houses themselves.
Slowly, his body began to adapt—not change, not shift, but vibrate. His Reiatsu spread out in circles, each of which glowed with a unique hue: violet for his Shinigami heritage, obsidian for his Hollow legacy, gold for the unnamable thing. The ritual was no mixing of races, but of ideals. The symmetry of Shinigami order, the randomness of Hollow instinct, and the divine spark which had coalesced within Kagami no Kami now flowed in harmony.
The world itself distorted in accordance. Reflections vanished, supplemented, and reconstituted. His past incarnations trembled like candle flame—some of them laughing, some of them bleeding, some of them crowned with fire. One of them was bound in the chair beneath Muken. Another was the so-called god of Karakura Town. Yet, they all lowered their heads as the current incarnate Aizen towered above.
He opened his eyes.
They held the starry glint now—not metaphorical, but a real cosmic vibration. The glow of exploding stars and galaxies in the process of creation seemed to ripple in his irises, trapped in an infinite spin. When he looked at his own hand, he did not perceive flesh, but energy—Reiryoku so focused it had become half-physical particles.
And yet, he never lost himself.
Most would have fallen—into madness, into obsession, into ravenous desire. But Aizen was unaffected as ever: distant, calm, superior. He knew the limits of power. Above all, he knew how to keep them hidden.