The Greatest Assassin Gets Reincarnated in Tensura

The bustling city streets were filled with the familiar sounds of life—cars honking, people chatting, the hum of civilization moving forward without pause. Among the crowd, Satoru Mikami, an ordinary 37-year-old man, walked with a relaxed demeanor. He had no grand ambitions, no deep regrets—just an easygoing life filled with routine.

But fate had other plans.

As he strolled through the streets, he noticed something off. A sudden commotion—a man wielding a knife, his eyes wild with desperation, lunging at someone. A friend? A coworker? A stranger? It didn't matter.

Satoru acted.

Instinct took over, and he stepped in front of the knife.

A sharp, searing pain erupted in his stomach as the cold steel sank deep into his flesh. Time seemed to slow. The sounds of the city dulled, the colors blurred. His body crumpled to the ground.

His vision darkened. His body was shutting down.

"Ah… so this is how I go?" he thought, his mind surprisingly calm.

Blood pooled around him, the warmth of life rapidly fading. As he lay there, he could hear the panicked voices around him, feel the distant presence of people trying to help, but it was too late.

His consciousness drifted.

And then, something spoke.

A mechanical, omnipotent voice echoed through the void.

[Conditions met. You have perished.]

[Releasing Soul from Mortal Constraints.]

[Unique Skills granted based on Final Thoughts.]

Satoru's fragmented, dying mind barely processed the words.

"Skills? What the hell is this…?"

But then, the Voice continued:

[Unique Skill: Predator acquired.]

[Unique Skill: Great Sage acquired.]

[Physical body no longer needed. Reconstructing existence in an alternate form.]

Darkness enveloped him. There was no pain, no fear—just an endless void. And then…

Rebirth.

A strange sensation coursed through his being. He no longer had limbs, no heartbeat, no breath.

His body felt soft, yet resilient. He was floating, drifting in liquid darkness.

His senses adjusted, and suddenly, he became aware of his surroundings. A damp, cool space. A cave. Stalagmites hung from the ceiling, water dripped somewhere in the distance.

"What… happened to me?"

He tried to move—and bounced.

His entire body jiggled unnaturally.

"Wait… why do I feel like a giant piece of jelly?"

Then it hit him.

"...Did I just reincarnate as a SLIME?!"

Panic surged for a moment, but then…

[Confirmed. Species: Slime.]

The voice again. It resonated within his mind, not intrusive, but clear. He wasn't alone.

A new world. A new body. A new existence.

And thus, in the depths of an ancient cave, within the vast Jura Forest of the Cardinal World…

Rimuru Tempest was born.

----_____----

Days laterrr....

The wind howled around the watchtower, standing high above the land, giving a perfect view of the vast Jura Forest stretching endlessly below. The night sky was clear, the stars twinkling above like scattered gemstones, and the moon cast a silver glow over everything. The scene was peaceful, yet my mind was focused on something far greater—the beginning of a new legend.

I sat comfortably on the cushioned seat at the center of the tower, Velzard leaning into my side, her soft breath warm against my skin. Testarossa, Ultima, and Carrera had also draped themselves around me, each of them enjoying their usual moments of indulgence.

Velzard traced a finger over my chest and smirked. "So, what's on your mind, Arion? You've been staring into the distance for a while now."

Ultima grinned. "Are we finally getting another mission? Or is this another one of your big plays?"

Carrera chuckled. "If it is, I hope it's something explosive."

Diablo stood nearby, hands clasped behind his back, his ever-present, devilish grin in place. "It must be something important if my lord is contemplating so deeply."

I exhaled, a smirk playing on my lips. "It's time."

The doors to the tower burst open with a gust of wind, and in strode Veldora—not in his dragon form, but his human form. His golden hair whipped in the wind, his long coat billowing dramatically behind him. He crossed his arms, eyes gleaming with excitement.

"FINALLY!" he boomed. "Is it my turn now?! The ladies get all the fun, and I've been stuck doing nothing!"

Velzard sighed, still leaning into me. "You and your dramatics, Veldora."

Ultima giggled. "He really is like a big kid."

Carrera smirked. "I kind of respect it."

Veldora ignored them, turning to me with anticipation. "So, what's the mission, Arion?!"

I gazed at him, my tone even but firm. "The Slime—he should have reincarnated by now."

Veldora's eyes sparkled. "Ohhh, finally!"

I leaned forward. "But listen carefully. This isn't a fight. This is the beginning of something greater."

Veldora tilted his head. "Huh?"

"In the original future—the one Chloe foresaw—you were sealed in the cave. You couldn't use your skills, trapped in isolation for centuries. Then the Slime, Rimuru, found you, consumed you with his ability, and stored you in his stomach. That's how your friendship began."

Veldora scowled. "Me? Sealed?! Who would dare?!" He clenched his fists, his aura flaring slightly.

I raised a hand. "Relax. That won't happen this time."

Veldora paused. "Oh?"

I smirked. "This time, you will guide him."

The others listened intently. Even Diablo's grin widened slightly.

Velzard raised an eyebrow. "How exactly?"

I turned back to Veldora. "You will still pretend to be sealed inside the cave. Play the role of the ancient, imprisoned dragon. When Rimuru arrives, he must believe he is the one helping you."

Veldora blinked, then a slow grin spread across his face. "Ohhhh… I see what you're doing."

Testarossa chuckled. "So he thinks he's saving you, but in reality, you'll be the one shaping his future."

I nodded. "Exactly. But that's just the beginning."

Veldora leaned in eagerly. "Go on."

I pointed toward the vast Jura Forest below. "The Slime won't stay in the cave forever. He will soon venture out and encounter the goblins living in this forest. He will protect them, lead them, and start building his own country."

Veldora's eyes widened. "Wait… his own country?!"

I smirked. "Yes. And not just any country—the strongest nation in the world."

Carrera whistled. "Not bad for a slime."

Ultima grinned. "This sounds like a fun story already."

Diablo chuckled. "So my lord has already foreseen the rise of a kingdom… fascinating."

I nodded. "Rimuru's nation will become the most powerful force in the world, but it all begins with you."

Veldora pointed at himself. "Me?"

I nodded. "You will watch over him, guide him from the shadows, and ensure he follows the right path. You are the first powerful being he will meet. You will be his first mentor."

Veldora's face lit up. "Oh, this is even better than I expected!" His booming laughter echoed across the tower. "HAHAHAHA! I get to train him, shape his journey, and still act like I'm the great, imprisoned dragon?! GENIUS!"

Velzard sighed. "Why do I feel like this is just going to feed his ego?"

Testarossa smirked. "Because it is."

Carrera chuckled. "As long as he doesn't mess it up."

I crossed my arms. "And don't worry, Veldora. I'll be watching over you. If anything changes, I'll step in."

Veldora grinned. "Then I have nothing to fear! The Great Storm Dragon enters the stage!" He turned dramatically, his coat flaring behind him. "The slime won't even know what hit him! HAHAHAHA!"

Ultima laughed. "This is gonna be hilarious."

Carrera smirked. "Poor Rimuru."

Velzard chuckled. "Let's just hope he survives Veldora's 'mentorship.'"

Diablo bowed slightly. "A most entertaining development, my lord."

I smirked. Everything was falling into place. The future had changed, and this time, it would be even greater than before.