Kurosaki Clinic
"Hope you come and visit again, ma'am."
Isshin Kurosaki flashed a warm, reassuring smile as he saw off one of his regular patients at the door of his modest clinic. His tone was easygoing, the smile never wavering as he waved goodbye. The soft chime of the doorbell rang in his ears as the patient disappeared into the gloomy streets outside.
Isshin leaned against the doorframe, his gaze shifting toward the grey sky above. The clouds were thick and heavy, suffocating the once-clear horizon. A light drizzle fell steadily, barely enough to warrant an umbrella but enough to set the mood. He sighed, his eyes narrowing slightly as the weather's melancholy matched the somber air that had settled in his chest.
This feels like an omen, he thought. A sign of something to come.
Just as he was about to turn back into the clinic, his phone buzzed, pulling him out of his thoughts. He reached for it instinctively, answering without hesitation.
"Kurosaki Clinic, this is Isshin Kurosaki speaking."
A pause. Then, a familiar, laid-back voice crackled through the receiver.
"Yahhh… Finally managed to get a reception here."
Isshin pinched the corner of his eyes in annoyance, recognizing the voice immediately. It was unmistakably Kisuke Urahara, the ever-aloof, carefree man who always seemed to be either laughing or scheming.
"Oh, it's you, Urahara. Haven't seen you in your shop lately. Where are you now?" Isshin asked, his voice light but tinged with curiosity.
"I'm licking my wounds and patching things up in Hueco Mundo."
Isshin blinked, the words striking him like a cold gust of wind. Hueco Mundo? He never thought Kisuke would find himself there, not after the climactic battle with Aizen that had forever altered their world.
"Hueco Mundo?" Isshin echoed, incredulity creeping into his voice. "Wait, what are you even doing there in the first place?"
The silence on the other end deepened, then Urahara's voice came, less jovial and far more serious.
"Your idiot son asked for my help. Said Nel came falling through here, talking about an army of Quincy decimating the place…"
Isshin froze, the phone now feeling heavy in his hand. For a long moment, he said nothing.
Both men knew what this meant.
"So it began then…" Isshin murmured, his mind racing with the implications. "How's Ichigo?"
Urahara sighed, his voice quieter now, more thoughtful.
"He faced him… and there's no surprise, he was outmatched. But you really need to listen closely. Mayuri called me about how the Wandenreich invaded the Soul Society. From what he told me, it seems we have another player in the mix."
"Another player?" Isshin echoed, his eyebrows furrowing in confusion.
"Yes. Right when Yhwach had his zanpakuto shattered in half, something happened that made me doubt what Mayuri told me."
Isshin's heart skipped a beat. He could hear the uncertainty in Urahara's voice—something about this news was unsettling, and Isshin felt it in his bones.
"And that is?" Isshin asked, his voice low, sensing the gravity in Urahara's words.
"His zanpakuto… it turned into a human being or something. And for a brief moment, he managed to outmatch Yhwach."
Isshin's jaw dropped. He'd heard of zanpakuto spirits briefly channeling their human forms, but never had he heard of a zanpakuto transforming into a human. And more shocking still—this being, whatever it was, had been able to go toe to toe with Yhwach himself—and had somehow won.
A heavy silence filled the line.
Isshin, who'd known Urahara for over a century, could tell that this wasn't some wild theory.
Urahara's voice, always filled with wit and playfulness, now carried a somber weight.
"Oi, Urahara… tell me you're lying about all that," Isshin muttered, a hint of disbelief in his tone.
Urahara's voice was serious, unwavering.
"That's why I'm finishing things up here in Hueco Mundo. I'm going straight to Mayuri. If what he said is true, then we may have a wild card in this war. One we didn't see coming."
Before Isshin could respond, a faint, yet powerful spiritual pressure washed over him, sharp and undeniable. His senses tingled with the familiar pull of reiatsu, and it was strong—almost too strong to be ignored.
"Sorry, Urahara," Isshin said, his tone suddenly urgent. "Gotta check something out."
He hung up the phone quickly, his eyes already scanning the area around him, every instinct on high alert. There was no mistaking the energy that lingered in the air—it was coming from the north.
He swiftly grabbed his coat from the chair and threw it on, his movements quick and decisive.
"Karin, Yuzu," Isshin called as he strode toward the door, his voice filled with a sudden sense of purpose. "There's somewhere I have to go. I trust you two can handle the clinic for me?"
His daughters, familiar with their father's unpredictable comings and goings, nodded without question. Isshin gave them a quick, reassuring smile before stepping out of the clinic and into the drizzly streets.
The pressure wasn't far. From where he felt it, it seemed to be coming from the north— toward the mountains.
Who… or what is out there? Isshin thought as his gaze hardened, his pace quickening.
Whatever it was, he would need to be ready. The weight of the moment hung heavy in the air, and Isshin knew that whatever awaited him up north, it would change everything.
Karasu River, 10 minutes later
Isshin reached the epicenter of the spiritual pressure he'd sensed earlier. As he approached, the sight that unfolded before him was nothing short of nightmarish. Countless public workers were frantically trying to manage the aftermath, but their efforts seemed insignificant against the devastation surrounding them.
Buildings, once standing tall, were sliced clean in half—some obliterated entirely, reduced to rubble. In other areas, deep craters marred the riverbank, like the land itself had been violently torn apart.
What in the name of Adyneus happened here? Isshin's mind raced. The scale of destruction was beyond comprehension. But even worse was the gnawing feeling that something unspeakably monstrous had been at the heart of it.
Disguising himself as a volunteer, Isshin pushed forward, his eyes scanning the chaos, though his body felt heavy with dread. He tried to keep his face neutral as he passed by countless victims, each one a casualty of this horrific event. Some were covered in blood, others limped with injuries that ranged from moderate to life-threatening. But nothing could have prepared him for what lay ahead.
The sight of dead bodies, lined up one by one, hit Isshin like a physical blow. His stomach churned, and for a split second, he felt the urge to turn and run. But he forced himself to stay.
To look.
Some bodies were mutilated beyond recognition—shredded beyond all hope of repair. Others had their limbs or heads torn away, a grotesque testament to the brutality of whatever had done this. A few had been burned, their skin charred beyond recognition, their faces frozen in expressions of pure terror. But there were others, too…
Some…
His breath caught as he stared at the faces of the dead, some with their faces locked in silent screams, their eyes wide with the terror of their final moments.
Some…
He had seen death many times before—his time as a Soul Reaper, and later as Captain of the 10th Division, had hardened him to it. But this… this was different. This was something so utterly monstrous, it left him feeling raw, exposed.
His stomach twisted as he swallowed hard, fighting the urge to throw up. He had been accustomed to death, to the carnage of battle. But never had he seen such a brutal, senseless massacre. This was beyond anything he could have prepared for.
Who could have done this? Isshin thought, his mind struggling to wrap around the sheer scale of the horror before him. Who would leave such devastation in their wake? They're monsters…
Just as the weight of the scene began to settle on him, something caught his eye—a figure being carried on a stretcher into an ambulance. He didn't have to look twice to recognize who it was.
Lisa… Hiyori…
Isshin rushed forward, weaving through the throngs of medics and public workers until he reached the ambulance. Lisa Yadōmaru and Hiyori Sarugaki were both there, pale and bloodied but alive. They weren't critically injured, but their faces told a different story— exhaustion, pain, and fear etched into their features.
"Lisa, Hiyori, are you both okay?" Isshin asked, his voice strained with concern, his eyes searching their faces.
Hiyori, as brash as ever, scoffed at him, her voice thick with frustration. "Do we look okay to you? We've been loaded here for fuck's sake!"
Isshin's eyes softened, his expression filled with sympathy, but he couldn't ignore the weight of the situation pressing down on him. He needed answers.
"What happened there?" he asked, his voice tight, hoping for something that could make sense of this nightmare.
There was a long pause. Hiyori, the fiery one, said nothing—clearly unwilling to recount the horrors she'd witnessed. But Lisa, ever the composed one, nodded, her face grim.
"We got a call from Shinji... He told us to be on the lookout for a man in a hoodie. Then, we saw Uryu alone by the riverbed. We were about to check on him when the man appeared— along with Ryuken."
A man in a hoodie? And Ryuken? Isshin felt his brow furrow. The pieces weren't fitting yet, but he had to know more.
"A small group of Quincies came and started attacking the hooded man," Lisa continued, her voice steady but laden with sorrow. "We saw the Ishidas manage to escape, so we began evacuating the civilians. But when we came back to check the battle… We just saw that man, standing tall over the fallen Quincy. All by himself."
Isshin's eyes widened in disbelief. "Wait, the man you were told to look out for… he won? Against those Quincies? And by himself?"
The air around them seemed to thicken as the three fell into silence. Lisa nodded, her eyes dark and distant as she spoke.
"There was another group that came shortly after. They picked up the fallen, but they couldn't reach the two behind the hooded man. There was a brief fight, and then… He just released his reiatsu—"
Lisa paused, swallowing hard. Isshin could see the fear in her eyes. This wasn't just about a battle—it was something much worse.
"Thankfully, we were able to hold out for a while… but we couldn't move. And those humans… they weren't as lucky." Lisa's voice trailed off, the weight of what she had witnessed clear in her expression.
Isshin closed his eyes for a moment, his heart heavy as he recalled the line of bodies he'd passed earlier. Each one a victim of a force he didn't understand, a force that now threatened everything. The pieces were starting to fall into place, and his worst fears were beginning to take shape.
Urahara had warned him about a third player. The man in the hoodie.
'He turned into a human being or something, and managed to outmatch Yhwach for a short period of time…'
Isshin felt a cold shiver run down his spine. This… man in the hoodie—if he was the one who had defeated Yhwach, if he was the one responsible for all of this destruction…
And then there was Ryuken and Uryu, somehow involved. What reason could they possibly have for working with him? Isshin's mind spun, trying to piece together the fragments of a puzzle he wasn't sure he was ready to solve.
Damn it, everything was a mess.
Isshin looked at Lisa and Hiyori one last time, his expression softening with genuine concern.
"You two, take care of yourselves," he said, his voice quiet but firm, before he turned to leave the ambulance.
As he walked away, his mind raced with the implications of what he had just heard. The world as he knew it was on the verge of unraveling, and there was no telling how deep this new threat went. Whoever this man in the hoodie was, he wasn't just some player in the game—he was a force of destruction, and the future of everything Isshin held dear was hanging by a thread.
Karakura Hospital, present time
Mercer suddenly appeared a few feet before the Ishidas, his landing rough and unsteady as he carried the unconscious bodies of Bazz-B and Bambietta. He staggered slightly, still not quite used to the unpredictable blend of Hirenkyaku and Shunpo that made his movements feel disjointed, but he didn't have time to adjust—time was always against him.
As he set the bodies down on the cold, cracked earth, Ryuken's voice cut through the air, cold and sharp.
"There was a release of reiatsu not far from here. I presume that must be during your battle with those you think would come for my son."
Mercer didn't flinch at Ryuken's ice-cold greeting, but his voice was flat, casual even, as he dropped the bodies to the ground.
"Pretty much, yeah."
His eyes flickered to Uryu, who stared back with disdain, his gaze thick with contempt. Mercer ignored it for the moment, knowing the rift between them was more than just personal—it was about survival.
He leaned against the wreckage of a building, the faint stench of smoke still lingering in the air. "Now, where was I? Oh, right... My name is Alex Mercer."
"Yeah, I've heard you before," Uryu replied, his tone like a venomous hiss. "Hard to believe you killed six million people out of spite."
Mercer's eyes narrowed, but his response was disturbingly calm. "Not really out of spite, but yeah, I did kill six million people."
Uryu's face twisted in disbelief, the horror palpable. The casualness with which Mercer spoke about such mass murder was enough to make Uryu's skin crawl.
This man, this… monster, he thought.
His mind flashed to Mayuri Kurotsuchi, another man with a soulless, clinical demeanor. The comparison made Uryu shudder—
Is that what I'm becoming?
Before he could speak again, Ryuken interjected, cutting through the tension like a knife.
"Tell me, what happens now that you've shaken off your pursuers?"
Mercer looked at Ryuken, his features hardening, eyes calculating.
"Not much," he answered nonchalantly. "For some reason, that first group appeared out of a portal, right here. I suspect they've been monitoring this world, watching everything unfold."
Ryuken's lips curled in slight irritation. "If that's true, then why didn't they bring the whole army?"
"The only reason I can think of is that it's pure revenge," Mercer explained, his voice lower now, tinged with a dark humor. "These guys are acting without their Majesty's permission." He pointed down at Bazz-B. "This one… He was talking about his friend, the one I consumed the moment I arrived. From what I gathered from the memories I dug up, they were childhood friends before they became Sternritters."
Uryu's eyes widened in disbelief as Mercer suddenly transformed, his form twisting and contorting into the likeness of Jugram Haschwalth.
"Shit," Uryu muttered, staring in awe and horror. The tendrils shot from Mercer's feet to his head, the transformation almost otherworldly, as if he was a completely different entity. His entire body changed—his face, his posture, the very essence of his being.
Who is this man? What the hell is he?
Mercer smirked, his voice cold and amused. "Now that this crap happened, I can't stay here any longer. They'll be back with the whole army. And honestly, I'm not sticking around for that."
Ryuken's expression hardened, his sharp gaze piercing. "Ah… I think so too. Your presence here won't just attract the Wandenreich. Sooner or later, the Soul Society will come hunting you down. And there are former Soul Reapers who might want to extend their cooperation in the manhunt."
"Don't forget about Grimmjow Jaegerjaquez, either. I don't know if he survived the chaos at Hueco Mundo, but if he gets wind of my existence, he'll come for me. No hesitation," Uryu added, his mind whirring, the possibility of Grimmjow being an added threat weighing heavily on him.
If this Grimmjow is as strong as these Quincies, we might not survive him, either.
But Mercer's voice cut through his thoughts. "Grimmjow, huh? I don't know who he is, but if he's anything like those Quincies, I'll consider taking the challenge."
Ryuken looked at Uryu, a brief flash of concern flickering in his eyes. "What's your plan, Uryu?"
Mercer's voice turned even colder, a sharp edge in his words. "I'll tell you what he's planning. Revenge. That's what you're all after, isn't it?"
Uryu's eyes widened, the words striking him like a punch to the gut. He hadn't realized it, but Mercer saw right through him, saw his motivations clearer than even his father did.
"You've been trying to avenge your mother. I get it." Mercer's tone was surprisingly serious now, his eyes narrowing as they met Uryu's. "But what's your plan, huh? Sneak up on Yhwach in his sleep and stab him in the back? You're all alone out here, and from the looks of you, you're just gonna get yourself killed."
The anger surged within Uryu, but Mercer didn't back down. The man was cold, unflinching—like a mirror reflecting the harshest truths.
"And even if you do kill him, you realize what'll happen, don't you? What'll happen to you… to everyone around you?"
The silence stretched long, the words hanging in the air like a threat.
"THAT'S ENOUGH!!!"
Uryu snapped, his voice trembling with fury as he reached for his Seele Schneider, his movements swift, desperate.
In response, Mercer's arms rippled and transformed into deadly, razor-sharp claws. The tension between them crackled, ready to explode.
But before either could strike,
THWACK!
Ryuken's fist connected with Uryu's face, sending him crashing to the ground.
The impact was deafening in the eerie silence that followed.
Uryu clutched his jaw, stunned. Mercer exhaled through his nose, retracting his claws, his stance shifting from predator to passive observer.
"I told you not to cross him," Ryuken warned, his voice carrying the same ice as before, but there was something else there now—something that wasn't just anger.
Mercer crossed his arms, looking down at Uryu. His voice was softer, but no less firm.
"You should've thought better than to side with the same man who took everything from you," he muttered. "Don't forget—you still have someone relying on you."
Uryu's breath hitched. His fingers dug into the dirt.
Memories flashed through Uryu's mind—Ichigo, always charging ahead, their rivalry, fighting Hollows side by side, breaking into Soul Society for Rukia, and Ichigo checking on him in the hospital.
Uryu's body shook—not from anger, but from the crushing weight of realization.
What the hell was I thinking? If I went through with this… I'd be no different from the people I hate. And Ichigo… he'd never forgive me. Hell, I'd never forgive myself.
His fists relaxed. The fight drained from his body.
"So?" Mercer's voice broke through the fog. "Now that I've called you out, what are you gonna do?"
Uryu swallowed hard. He looked up at his father, then back at Mercer.
"…I'll go with you."
Ryuken's jaw tightened. He said nothing.
"But on one condition."
Mercer raised an eyebrow. "Name it."
Uryu's eyes burned with intensity. "If you ever lay a hand on my friends… then we're done. And I'll come for your head—even if it kills me."
Mercer smirked slightly, but there was no humor in it. Just understanding.
"I can't guarantee that," he admitted. "But I'll try my best."
Uryu exhaled. "…Fair enough."
An uneasy alliance was born. Fragile. Dangerous.
Then—
A voice rang out behind them.
Casual. Familiar.
"Yo… fancy meeting you three here."
Uryu's heart stopped.
Slowly, they turned.
Standing just a few feet away, his posture loose, but his eyes sharp and knowing—
Isshin Kurosaki
The air was thick with tension as Isshin's voice cut through the stillness. His eyes were icy, narrowing as he addressed Ryuken and Uryu with a fury that seemed barely contained.
"Ryuken, Uryu, what's the meaning of this?" His words were calm, almost too calm, but his hands clenched into fists, a physical manifestation of the rage he struggled to hold back. "You two are working with this monster wearing human skin? Are you out of your mind?"
Isshin's gaze then turned to Mercer, his contempt almost palpable. "And you, do you really think you'll walk away after everything you've done back there?"
Ryuken's eyes widened, knowing exactly what Isshin was referring to. He opened his mouth to defuse the situation, but Isshin wasn't interested in reasoning.
"Cut the crap, Ryuken. I think I demand to know what you two are doing," Isshin spat, the fury in his voice now undeniable. "I can't just stand by while you side with a thing that's slaughtered innocent people—without a second thought."
Mercer didn't flinch. His voice came with the same cold edge as before, but this time, there was a growing frustration beneath the surface. "Well, maybe you didn't know, but we were under attack by your mortal enemies—the ones you thought were extinct. I had no choice but to act accordingly."
Isshin's anger flared even higher. "Just like how you 'acted accordingly' back at Soul Society?" His words were sharp as knives, each one cutting deeper.
Mercer's expression hardened, and he stepped closer, his voice low and dangerously calm. "It's not my fault. I tried to explain myself, tried to offer a hand. What I got in return was an attempt on my life." His hands clenched, eyes narrowing as the memory of Kensei's reckless attack played in his mind. "I'm not here to make enemies, but when someone tries to kill me, what do you expect me to do?"
The tension between the two men simmered dangerously. Ryuken watched, his own mind racing. He knew Mercer wasn't lying.
But still... he thought, glancing at Uryu, who stood silently behind him, eyes hard as stone.
How can I justify this?
"You can't just kill people, Mercer!" Isshin roared, his fists clenched tightly at his sides. "Innocents died at the river! That's on you!"
Mercer didn't back down. "It's pretty unfair to blame all those deaths on me when I wasn't the only one fighting there, don't you think?"
Isshin froze, the weight of the words hitting him. His face twisted with anger and confusion, his jaw tightening as he struggled to come to terms with the truth. He opened his mouth to say something but stopped mid-sentence. It wasn't worth trying to reason anymore.
"Well, if there's no point talking you down, then I'll have to do this the hard way," Isshin muttered, preparing a Kidō spell, his reiatsu surging as the air around them crackled with energy.
Mercer's eyes flashed dangerously, his body tense, as if the challenge was the only thing he had been waiting for. "Try me," he snarled, his voice low and filled with menace.
Just as the two seemed ready to clash, Ryuken moved swiftly behind Isshin, his Heilig Bogen aimed directly at his back. The deadly silence that followed felt suffocating.
"Isshin... Let them go. I'll take full responsibility," Ryuken's voice rang out, a plea that cut through the rising storm of emotions. His voice held a calm urgency, but it was clear he didn't want this fight.
Isshin's face twisted in shock as Ryuken's weapon hovered at his back. "Idiot!! What are you doing?" Uryu's voice cracked, his frustration boiling over as he looked between the two men.
Ryuken's voice was steady, but his eyes held a quiet desperation.
"SILENCE!! YOU TWO JUST GO. I'LL HANDLE THINGS FROM HERE."
Isshin's gaze turned cold, his shoulders slumping slightly as the weight of Ryuken's words settled on him. He wasn't happy, but there was no other way out.
"You better have a good explanation for this," Isshin finally said, his voice bitter, yet reluctant to escalate further. "I know you won't align yourselves with a monster without good reason."
Mercer's expression softened slightly, a silent acknowledgment of Ryuken's sacrifice. "Thanks," he muttered, and with a quick, fluid movement, he tapped his foot against the ground.
The world seemed to shift. From beneath his feet, tendrils of dark energy rose, twisting and writhing as they formed into a rectangular shape—a door. The very sight of it left Ryuken, Uryu, and Isshin stunned.
Incredible... Ryuken thought, his eyes widening in disbelief. That's... a portal to another realm. And he summoned it with ease. He glanced at Uryu, who was equally stunned. We soul reapers need our zanpakuto to open these kinds of gates. Hollows and Arrancars have to use a Gargantua. But Mercer? He just... tapped his foot and made a doorway to somewhere else appear. What in the world is he?
Mercer didn't look back as he picked up Bazz-B and Bambietta, effortlessly slinging one over each shoulder. With a brief glance at Uryu, he motioned toward the door.
"Let's go, kid," he said, his voice colder now.
Uryu hesitated, stealing one last look at Isshin and his father. He didn't want to leave, didn't want to walk this path... but the weight of Mercer's words, the promise of something greater, lingered in the air. He turned to follow, the door before them dark and beckoning.
As the door swung open and Mercer entered, the tendrils of reishi quickly closed behind him, sealing the portal and dispersing into the air. Uryu's eyes flickered over his father one last time. Ryuken said nothing, but his gaze was heavy with unspoken emotions. He didn't want to look at Isshin—didn't know how to explain this to him, not yet.
With that, Ryuken stepped toward the door, his eyes cast downward. As the nurse appeared, frantic and worried, he gave a single nod.
"Doctor Ishida, we need you at the ER."
Ryuken didn't hesitate, walking swiftly to leave the rooftop. But as he looked around, Isshin was nowhere to be seen.
The weight of the moment hung between them all, like a lingering shadow that couldn't be escaped.