Slime Soul (Tensura x Bleach Crossover) (Patreon)

Chapter 19: Unseen Agenda

Standing at the epicenter of Kurohitsugi, where gravity warped space and crushed inward from every direction, I felt… nothing.

Spatial Domination rendered it utterly meaningless.

Raising a hand, I silently invoked Beelzebuth.

The black coffin of distorted space trembled—

—and was devoured.

In an instant, the technique vanished as though it had never existed, its immense energy flowing cleanly into my reserves held in Imaginary Space.

Across from me, Aizen stared in disbelief.

I slowly closed my fingers, letting the skill dissipate.

“Thank you for the meal.”

“I–Impossi—Ghhk!”

His disbelief was cut short.

Using Instant Motion, I appeared at his side in a literal instant and drove a right hook into his jaw. The impact sent him hurtling across the battlefield and straight through a cliff face in an explosion of stone.

‘Noted,’ I thought calmly. ‘Thought Acceleration pairs best with Instant Motion for future reference. Without it, there’s minor spatial disorientation at instantly appearing at the new location. Luckily it’s not much and something I can do unconsciously if I wish.’

The cliffside detonated as Aizen reappeared beside me, using his own teleportation technique though one much slower than mine, fury distorting his face, blade already descending.

Too slow.

I vanished again.

Appearing at his flank, I drove my knee into his abdomen. He folded. My elbow came down on the back of his neck an instant later, slamming him into the ground hard enough to crater the earth in his shape.

“HOW!?” he roared.

He teleported behind me, slashing wildly.

I was already gone.

“How are you faster than me!?” Aizen snarled as spiritual pressure erupted from him in violent waves.

His body twisted, evolving again due to his rage, shedding the last remnants of his human appearance. Wings warped. Flesh shifted. His form became something closer to a hollow than a Shinigami now with his face resembling a hollow mask and the rest of his body being all white.

“I have transcended Shinigami and Hollow alike!” he thundered, his voice much rougher than before. “So how are you still faster than me!? Why am I still unable to sense you after evolving to this extent!? How are you stronger than me!?”

“It’s simple,” I answered calmly, raising my hand to devour the beams of energy launched from the small skulls on Aizen’s wings. Beelzebuth swallowed them whole, doing nothing but adding more energy to my reserves.

“You and I have different ceilings of power.” I replied calmly, weaving through his attacks without effort as he abandoned energy attacks and attacked me with his Zanpakutō.

“Your soul can only contain so much power. No matter how many times you evolve, there is a limit.”

I stepped inside his guard.

He missed again.

“I don’t have that limitation.”

I tilted my head slightly, a faint smile touching my lips.

“I’m still very young, if you can believe it. I’m not even a year old physically.”

His eyes widened.

“That means I’m nowhere near my peak.”

I disappeared—

—and reappeared behind him, blade flashing.

His wings fell in two clean arcs.

Aizen howled as my blade devoured fragments of his life force through Memory End Requiem.

“Sorry,” I said quietly as he staggered.

“But if you want the simple answer…”

I leveled my sword at him, crimson light bleeding along its edge.

“I’m built different.”

Aizen growled in pain before forcing himself upright, his face twisting into a venomous sneer.

“C-Caius Aurelius… Y-You… I WILL KILL YOU!” he roared as he launched himself at me once more.

But I was no longer paying attention to him.

My gaze had already shifted to the side, where an overwhelming spiritual pressure had suddenly erupted into existence.

Ichigo was done with his training.

“Seems my part is done for now,” I muttered.

Using Instant Motion, I sidestepped Aizen’s charge and reappeared above him in the same breath. Pouring all my current strength into one strike, I drove my fist into him and sent him crashing straight into the earth below, carving out a massive crater as his body disappeared deep underground.

A moment later, I returned to my original position.

With a snap of my fingers, the barrier I had erected earlier dissolved, allowing the outside world to sense us again.

Almost instantly, I felt Ichigo rushing toward us at tremendous speed. He appeared beside me in a flash, the fastest Shunpo I had seen so far. Only Aizen’s teleportation surpassed it.

“Took you long enough,” I muttered, letting my blade dissolve and storing it within Imaginary Space without even turning toward him.

“Sorry I’m late,” Ichigo replied calmly.

He sounded different. Older. Steadier.

He was taller too, nearly my height now. Before, he barely reached my chin. Now, he almost reached my nose.

“At least you don’t look like you’re about to cry anymore,” I added lightly before finally turning to face him.

He looked exactly as he had in my memories of this moment, his sword fused with his hand, Shihakusho torn and flowing, hair slightly longer.

But it wasn’t his appearance that stood out.

It was his composure.

Instead of firing back with an insult like usual, Ichigo simply nodded at me.

“Thanks for doing this, Caius. I know you didn’t have to… but you still did.”

I frowned faintly at that.

He didn’t know my plans for Aizen. He didn’t know what I intended to do afterward, or how that might affect Soul Society.

Calling him naïve would’ve been easy.

But I swallowed the words.

‘I wonder if you’d still thank me if you knew that I had a similar plan to Aizen’s and later Yhwach. The removal of the Soul King.’

Instead, I gave a small nod.

“Finish it quickly. The Hōgyoku is constantly forcing him to evolve. If you drag this out, he’ll eventually surpass you,” I warned.

Then, before he could respond, I vanished with Instant Motion and reappeared at a safe distance.

Time to watch the final act unfold.

=====

Ichigo’s POV

Waiting for Aizen to resurface after being sent who knows how deep underground by Caius, Ichigo couldn’t help but think about his enigmatic friend.

He wasn’t worried about Aizen anymore. Not after everything he had endured in the Dangai. Not after instinctively learning the Final Getsuga Tenshō and realizing that he had surpassed the seemingly unstoppable monster.

When he first returned from his training, the very first thing he did was search for his sisters and friends. The moment he sensed them safe, he let out a breath he hadn’t realized he was holding. They were shaken, yes — but unharmed.

That had been enough.

What he found strange, however, was that no matter how hard he focused, he couldn’t sense either Aizen or Caius.

Just as worry began creeping into his mind, Aizen’s spiritual pressure suddenly flared back into existence.

But Caius?

Still nothing.

Come to think of it, ever since meeting him in Hueco Mundo during the mission to rescue Inoue, Ichigo had always known the mysterious slime was strong.

That understanding only deepened over time.

After Caius evolved, Ichigo could no longer sense him at all. And even now, after gaining this overwhelming power, he still couldn’t detect a trace of him.

That was unsettling.

Even more unsettling was how absurdly fast Caius had grown.

Rukia and the others had once commented on how quickly Ichigo himself had become so strong. But looking back now, his growth was nothing compared to Caius.

It was as if his friend had no ceiling.

As if he could simply keep climbing endlessly after every battle.

Caius had easily defeated Ulquiorra, an enemy Ichigo would have died against if not for his Hollow. Then he had subdued Ichigo’s own inner Hollow, which, according to Inoue and Uryu, had seemed even stronger than Ulquiorra at the time.

And that was after already dealing with the Zero Espada.

One after another, Caius had handled them as if it were nothing.

That had been one of the main reasons Ichigo had swallowed his pride and asked for help back in the World of the Living.

If he was honest with himself…

He simply couldn’t imagine Caius losing against anyone.

Whenever Ichigo stood near him now, with all this new power coursing through his veins, Caius still felt like something else entirely.

Like standing beside a bottomless abyss.

An endless depth of power.

Even though Ichigo couldn’t sense a thing.

The only thing that unsettled him was Caius’s attitude toward the Soul Society… and that comment about how they would either kill or seal him if they truly understood what he was.

Shaking those thoughts away, Ichigo focused on the present.

At that moment, Aizen finally emerged from the crater, rage twisting his features. Features that no longer resembled the Aizen he had known.

“Where is he?!” Aizen roared, eyes darting wildly. “Where is Caius Aurelius?!”

“Sorry, Aizen,” Ichigo said calmly as he stepped forward, confidence radiating from him.

“But I’ll be your opponent now.”

His grip tightened around Tensa Zangetsu.

“It’s time I finally put an end to all this.”

He lowered his stance, black reiatsu gathering around him like a storm.

“Let me show you…”

“My Final Getsuga.”

=====

Back With Caius

I watched calmly as Ichigo became engulfed in a towering storm of reiatsu, signaling the use of the Final Getsuga Tenshō, and waited.

Moments later, his new form became visible, long black hair flowing behind him, red eyes glowing coldly, bandages wrapped around his torso. Most obvious, however, was the absence of his Zanpakutō in his right hand. In its place, he held a blade seemingly forged from pure darkness.

I didn’t react when I felt another presence enter my senses. I already had an idea who it was. I simply waited.

Ichigo raised his hand calmly… then brought it down as if passing judgment.

The sky turned black for several kilometers as the attack struck Aizen dead center, splitting him in half.

“Seems it’s over,” I muttered to myself, already preparing to intervene. I knew Aizen couldn’t truly die from that attack. The Hōgyoku made him immortal.

But he would be immensely weakened.

‘Are you ready, Raphael?’ I asked internally as I shifted back into my slime form. ‘You’re about to receive your own name very soon.’

There was a brief pause before she answered in a slightly shy tone.

“I-I’m ready, Master.”

Then, more clearly—

“Now please focus on the plan.”

I chuckled softly at her abrupt shift in tone but kept my eyes on Ichigo and Aizen, already sensing Ichigo’s power rapidly fading.

“Showtime.”

And I disappeared.

It was time to finish what Ichigo couldn’t… and erase Aizen for good. More importantly, it was time for my partner to finally get a name for herself.

=====

Ichigo’s POV

Frowning as he looked down at Aizen’s body, Ichigo expected to see a dying man.

Instead, he saw Aizen whole, regenerating rapidly from Mugetsu.

The only thing not regenerating were the stumps on his back where his wings had once been. As Ichigo watched, Aizen evolved again, his form shifting into something more human once more.

Still alive.

Ichigo immediately used Shunpo to appear in front of him, intending to deliver one final blow before his power vanished completely.

But at the last moment, his form reverted to normal.

The overwhelming strength he had possessed moments ago vanished.

A crushing weakness swept through him, forcing him to steady himself before he collapsed face-first onto the ground.

He breathed heavily.

His Final Getsuga was gone.

“Hahahaha, I’ve won, Kurosaki Ichigo!” Aizen yelled triumphantly as he rose back to his feet, now mostly returned to normal except for his white skin and the half-mask fused to the side of his face.

“While you’ve lost your power in one final, feeble attempt to kill me, I have evolved yet again thanks to the will of the Hōgyoku!” Aizen declared loudly before glancing down at his disintegrating Zanpakutō.

“Look! The Hōgyoku has deemed that I no longer need a Zanpakutō. With this new power, I will finally be able to match Caius Aurelius in strength. I will not allow that creature to trample everything I’ve worked toward for centuries!” he raved, his voice tinged with delirium.

“I-It’s over, Aizen,” Ichigo breathed out tiredly, glaring up at him weakly. “Like you said… Caius is still alive. Even if I failed to take you down, I know he won’t.”

His voice carried absolute confidence.

“Fool!” Aizen sneered, eyes flashing with contempt. “You have no understanding of that creature’s true nature, do you? Do you even know what he intends to do in the future!? Even if I fail, the Soul King will die one way or another!”

“…What do you mean?” Ichigo asked, confused.

“Hahaha! Naïve! You are painfully naïve, Kurosaki Ichigo! I mean that Caius Aurelius, the one you rely on so much, will ultimately be the one to—Ghhk!”

Aizen choked.

Ichigo blinked.

A crimson spike of energy had erupted through Aizen’s chest.

Before Ichigo could process it, a familiar voice spoke from behind him.

“Congratulations, Kurosaki-san. Thanks to you weakening Aizen to this extent, the sealing Kidō I used earlier is finally taking effect.”

Ichigo turned to see Urahara Kisuke walking toward them calmly.

Looking back at Aizen, Ichigo saw more red spikes piercing through his back.

“Urahara Kisuke! You bastard!” Aizen roared as his transformation unraveled, his form reverting to normal, save for his long hair.

Before Urahara could reply, Aizen suddenly coughed up blood surprising everyone.

Slowly… he looked down.

A hand was protruding from his chest.

In that hand—

His still-beating heart.

“…What?”

A swirling void of purple and black opened around the hand, expanding in an instant.

Aizen was devoured completely.

The last thing Ichigo saw was Aizen’s furious glare directed at the man now standing before him and Urahara.

“…C-Caius?”

Caius turned, meeting Ichigo’s eyes.

There was no triumph there.

No mockery.

Only a blank expression reflected in glowing golden eyes.

Beside him, Ichigo sensed Urahara tense. His hand rested on his sword, eyes hidden beneath his hat’s shadow.

“Sorry, Ichigo. But I need this.”

Caius didn’t spare Urahara a glance.

And then—

He vanished from Ichigo’s senses entirely.

“Dammit.”

That was the last thing Ichigo heard Urahara mutter before everything went dark.

Overwhelmed by the day’s events… and drained by Mugetsu…

Ichigo Kurosaki lost consciousness.