Slime Soul (Tensura x Bleach Crossover) (Patreon)

Chapter 18: Outside the System

Immediately upon exiting the Dangai, I headed straight for the Seireitei, slipping inside the city with ease before making my way to the Shinigami Academy. Acquiring blank Asauchi proved slightly annoying at first, so I simply located the nearest instructor by their spiritual power and extracted the necessary information from their memories.

Swallowing plenty of swords into my Infinity Space, I didn’t linger. I moved at once toward Aizen’s location, hoping I’d arrive in time, though I wasn’t overly concerned, given Gin’s… complicated loyalties.

Now, standing across from both Aizen and Gin, it seemed my instincts had been right.

“Right back at you, Sōsuke Aizen,” I replied calmly, keeping both him and Gin well within my senses.

“Curious,” Aizen murmured. “Even now, I can’t detect a single trace of Reiryoku from you. I wonder what kind of ability you’re using to hide yourself so completely.”

Gin, unlike his former captain, didn’t look amused. His smile was gone, eyes narrowed as he studied me with open suspicion.

“W-Who are you?” Rangiku asked warily, glancing between the three of us. The unease in her voice was echoed by the humans standing behind her.

“Before we continue,” I said, ignoring her for the moment, “why don’t we take this somewhere else, Aizen?”

He raised an amused eyebrow, but I was already turning away, facing Rangiku and the others, Ichigo’s friends, according to my memories, and that loud, oddly dressed man whose name I never bothered to remember.

Subtly invoking Mammon, letting my authority seep into the air, I spoke a single word.

“Sleep.”

Rangiku and the humans collapsed instantly, dropping where they stood as if their strings had been cut.

When I turned back, Gin had a hand on his Zanpakutō, body tense and ready.

“Fascinating,” Aizen said, briefly glancing at the unconscious group before returning his attention to me. “To think that you have already acquired the ability to affect other’s minds to this extent.”

Gin’s tension only deepened, which seemed to amuse Aizen even more.

“As for your suggestion,” Aizen continued lightly, “such a request can only be made by someone of equal standing.”

He blinked.

The figure before him dissolved into black smoke.

I reappeared behind Gin and devoured him with Beelzebuth in a single, brutal instant, giving him no warning, and no chance to react.

A moment later, I stood once more where I had been originally, my expression blank.

“My apologies,” I said calmly. “But I wish to discuss something with you rather sensitive, and I’d prefer not to have someone with… dubious intentions listening in.”

Aizen stared at the empty space where Gin had been, then chuckled, clearly delighted.

“Hoh,” he said. “I must say… you’re exactly the kind of person I was hoping you’d be.”

“Very well. You’ve caught my interest. Lead the way,” Aizen said, gesturing vaguely into the distance.

Nodding, I vanished in a brief burst of Sonido, reappearing high in the air. Aizen materialized behind me almost instantly. We repeated the process several times, leapfrogging across the sky until I was satisfied that we were far enough away for our eventual clash not to level anything—or anyone—by accident.

I could have teleported instantly using Spatial Domination, but that would’ve been pointless. Aizen wouldn’t have been able to follow me without sensing my position, and I wasn’t about to reveal that particular card before our fight had even begun.

When I finally landed, Aizen arrived an instant later. I exhaled softly and turned to face him in earnest.

“Before we trade blows, there’s something I want to ask you, if you don’t mind,” I said casually.

Aizen raised an eyebrow, then nodded. “I see no issue with that. I have a few questions of my own.”

“Good. Then give me a moment. I’d like us to have a bit more privacy.”

With a snap of my fingers, a barrier expanded outward, sealing off a wide area around us.

The Material Area, a barrier spell Raphael had recreated specifically for situations like this, isolated the space completely from the outside world. No sound, no perception, no interference. This should not only keep anyone from the Soul Society, Soul King’s Palace or the Wandenreich from listening in.

Aizen studied the boundary, his strange eyes, purple sclera and silver pupils, shifting slightly as he examined it.

“Once again, fascinating,” he murmured. “You’ve isolated this space entirely. It’s almost as though we’re standing in a separate world.”

He turned back to me. “What could you possibly want to ask that requires this level of precaution?”

“Tell me this,” I said evenly. “If your plan succeeded, if you created the Ōken, how did you intend to deal with Ichibē Hyōsube?”

For the first time, Aizen’s composure cracked.

“Surely,” I continued calmly, “you’re aware of his power if you truly intended to supplant the Soul King.”

Ichibē’s ability was absurd. Absolute authority over the true names of everything that fell under the Soul King’s power. To rename a being was to redefine what they were. Reduce someone to ‘black,’ and they would inherit the power of black itself. It was a terrifying concept.

Normally.

The only reason I wasn’t concerned was due to Raphael having my back, and the fact that Ultimate Skills should override such authority since they originated from the Creator of Everything itself. Not to mention the small detail that I didn’t belong to this universe to begin with.

Aizen stared at me.

True, genuine shock flickered across his face the instant I spoke Ichibē’s name aloud, and suffered no consequence.

The man had created a taboo on his name, where anyone unworthy to speak it would lose their voice.

Such a taboo held no power over me.

It took several moments before Aizen recovered himself. When he did, his expression was no longer merely amused, it was cautious, yet burning with even deeper curiosity.

“I see,” Aizen muttered. “If you know that much, then you must already be aware of the thing that sits atop this world.”

A faint sneer crossed his face when he said “thing”, his disdain for the Soul King unmistakable.

I nodded, and he continued.

“The answer lies within the Hōgyoku itself, its ability to materialize desire and the immortality it grants me. And while powerful, that old monk should still be susceptible to my Zanpakutō’s abilities.”

I considered his words, exchanging silent calculations with Raphael and we determined that while difficult, it was not impossible.

“…I see,” I said at last, giving a small nod. “Thank you for answering.”

Aizen didn’t miss a beat.

“Then allow me to ask you something in return,” he said, his tone sharpening. “What exactly are you? And where do you come from?”

“What am I, huh?” I murmured, thinking for only a moment before a smile tugged at my lips. “I’m just a slime. One that got lucky enough to be gifted with… extraordinary power.”

Aizen’s eyes narrowed slightly, studying me.

“As for where I come from,” I continued, my tone turning playful, “that’s a far more interesting question. One I don’t actually mind answering, since I plan on killing and devouring you after our fight.”

I said it as casually as commenting on the weather.

Before he could respond, I went on.

“Now I’m sure someone as knowledgeable as yourself, already knows this much, but I will repeat it just in case. The Three Worlds—the Soul Society, the Human World, and Hueco Mundo—were once a single realm. A realm called The Primordial Sea. It was there that the Soul King was born, before he separated reality into its current form.”

“At some point, while the realms were still united, that world was threatened by a ‘darkness.’ One that the Soul King managed to repel.”

I watched Aizen closely as I spoke, noting how intently he listened.

“But tell me,” I said, raising an eyebrow. “Have you ever wondered where that darkness came from?”

Raphael and I already had our suspicions.

Based on what I knew from my fragmented memories on the world of Tensura, the invaders likely came from the Otherworld, which was populated by Aggressors. Which consisted of Cryptids, Insectoids, and Phantoms. A race of beings that made it their goal to travel to other worlds and realities to conquer them.

If the Soul King truly faced one of them, then he was lucky since it meant it was probably one of the weaker ones.

Had a stronger one crossed into this universe…

This world wouldn’t exist anymore.

Aizen contemplated my words for a long moment before finally leveling me with an open look of shock.

“Are you saying,” he asked slowly, “that just like that darkness… you yourself come from outside this reality?”

“Correct,” I replied with a nod and a faint smirk.

“Prove it!” he snapped immediately, his expression hardening.

“My existence itself is all the proof you need,” I said calmly, pointing at myself. “You’ve been wondering why you can’t sense me, haven’t you? Even after all your evolutions, even after becoming stronger each time.”

I shook my head slightly, cutting him off before he could respond.

Extending my hand, palm up, I willed black-purple flames to form above it, coiled with crackling black-violet lightning.

“Tell me,” I asked, tilting my head, “can you sense any reiryoku coming from these flames?”

I answered for him before he could speak.

“You can’t. That’s because I’m not using reiryoku to create them.”

“You’re using an entirely different form of energy…” Aizen muttered, eyes locked onto the flames with intense focus.

“Now you understand,” I said, dispersing them a moment later. “This energy is created by manipulating spiritrons, the building blocks of spiritual matter, to form what are known as magicules. I then shape them freely with my will.”

“Think of it as a far purer form of reiryoku. One that beings such as myself can manipulate, but wholly different from the spiritual life forms of this universe.”

Aizen remained silent for a long time, his thoughts clearly racing.

Finally, he looked at me again.

“Then why tell me all this,” he asked flatly, “if you plan to kill me? What is your purpose?”

“My purpose,” I answered without hesitation, “is to leave this world behind and return to the Central World, where beings similar to myself exist.”

My voice hardened.

“I have no intention of coexisting with this world. Frankly, I don’t like it.”

Then I pointed directly at him.

“But to leave, I need more power. That’s why I will kill and devour you. And after that, I will do the same to anyone who stands in my way, including the Soul King and his personal guards.”

“You,” I continued coldly, “and the Hōgyoku will become fuel for my goals.”

A long silence followed.

Then Aizen’s shoulders began to shake.

Soft chuckles escaped him at first… before erupting into full, manic laughter as he threw his head back.

“HAHAHAHA!” he roared. “For a moment there, I almost believed you!”

His eyes snapped back to me, blazing.

“What a ridiculous fantasy! You’re nothing more than someone who managed to transcend the limits of Hollow and Shinigami alike!”

His spiritual pressure surged violently as his body underwent another evolution, four massive wings tearing free from his back.

“Let us waste no more time, Caius Aurelius!” he shouted, smiling wildly. “Just as you declared your intentions, allow me to declare mine!”

“I will kill and devour you,” Aizen proclaimed. “And with your power, I will finally ascend and become the god of this world!”

I watched him in silence, then sighed and shook my head.

Inwardly, though, I was smiling.

Throughout our entire conversation, I had been quietly using Mammon, subtly manipulating his emotions, testing whether such abilities could affect someone who could control the five senses.

The answer was clear.

Yes.

‘Looks like it’s confirmed,’ I thought calmly. ‘Ultimate Skills override everything in this world. The Almighty. Ichibē’s power. All of them have gone from serious threats to major annoyances at best.’

‘Seems we really did luck out, Raphael.’

“Master did not require an Ultimate Skill to prevail in the first place,” Raphael replied evenly. “Given sufficient time, even such formidable abilities would have been overcome.”

Her faith in me only made my smile widen.

‘Let’s get this over with,’ I thought as my new blade appeared in my hand, gripping it and immediately feeling how perfectly it fit.

Raphael had gone to work on the Asauchi I’d retrieved earlier, breaking several of them down into their base metal before saturating the refined ore with my magicules. Since we already knew that any material bathed in sufficient magicules would naturally transform into magic ore, the process took only minutes before the conversion was complete.

From there, Raphael consumed the magic ore and refined it further, compressing and purifying it into magisteel.

Using the finished magisteel, she recreated my new blade.

To my pleasant surprise, it manifested as a Unique-grade weapon.

A moment later, the blade took on a deep crimson glow, radiating an ominous presence as I activated Memory End Requiem, an Art granted by Asmodeus. With it, my blade could reap the life force of anything it cut, converting the stolen vitality directly into usable energy.

A perfect weapon for spiritual beings.

Shinigami. Hollows. And whatever Aizen had become.

The next instant, we met in the middle.

Our blades clashed, and the impact alone caused the surrounding terrain to fracture and collapse, the ground screaming as it gave way under the force. I felt it immediately, life force siphoned from Aizen through the contact.

He noticed too.

A sneer twisted his expression as we continued exchanging blows.

As we fought, a realization settled in.

I had grown ridiculously strong.

Parrying Aizen’s attacks required no effort at all, even though I wasn’t using Thought Acceleration, a far cry from the days when even a Gillian had pushed me some shortly after arriving in this world.

“What’s wrong, Aizen?” I asked calmly as our blades collided again, my sword stealing more of his vitality. His eyes flicked warily to the crimson glow. “From what I’ve seen, you’re usually much more talkative when you fight.”

Normally, he mocked. Lectured. Looked down on his opponents.

This time, nothing.

My words finally drew a reaction.

Snarling, Aizen disengaged and flashed backward, creating distance before raising one hand skyward.

“Silence, creature, and be crushed to pieces with Kidō!” he roared.

“The oozing crest of corruption! The arrogant vessel of madness!

Deny the seething urge—stun and flicker!

Disrupt the sleep!

The crawling queen of iron!

The eternally self-destructing doll of mud!

Unite! Repulse! Fill the earth, and know your own powerlessness!”

“HADŌ NUMBER NINETY—KUROHITSUGI!”

A monstrous violet pressure crashed down as space itself warped. In an instant, I was encased within a massive black coffin of spiritual energy, its gravity distorting time and space alike.

“Now that I transcend both Hollows and Soul Reapers,” Aizen declared triumphantly, “this is Kurohitsugi cast with a full incantation! It unleashes enough gravity to warp time and space!”

“The likes of you could never comprehend it, Caius Aurelius!”

The likes of me, huh?

I almost scoffed.

He was speaking to someone who possessed Spatial Domination. To someone wielding Beelzebuth, a power capable of devouring all phenomena in the universe.

No matter how refined or powerful this Kidō was, to me…

It was meaningless.

‘I think it’s time you learned a little humility, Aizen,’ I thought calmly, my expression utterly blank.