The Greatest Assassin Gets Reincarnated in Tensura

The watchtower was buzzing with energy. It was a crystal-clear night, and the Jura Forest stretched below us like an endless ocean of trees. But our attention wasn't on the stars or the wind that whispered through the mountains—it was on a floating magical screen that displayed the scene inside the cave in real-time.

I sat comfortably, Velzard curled up beside me, her hand resting lightly on my chest. Testarossa was beside me, her eyes sharp with curiosity. Ultima and Carrera leaned forward excitedly, their faces filled with amusement. Diablo stood behind us, arms crossed, his ever-present smirk lingering as he observed.

This was no ordinary surveillance. I had taken inspiration from my past life's technology—satellites, cameras, livestream feeds—and replicated them through magic. I had perfected a projection spell, allowing us to observe events in real-time as if we were watching a movie. One of my elite spies from the Black Legion had been assigned a single task: Follow Veldora and the Slime, record everything, and report back.

The projection flickered slightly before stabilizing. The cave appeared in stunning clarity—damp, dark, but eerily beautiful. Stalagmites jutted from the ground like ancient teeth, while underground lakes shimmered with an otherworldly glow.

Shadows danced along the walls, cast by faintly glowing crystals embedded in the rock.

And in the middle of it all…

A small, bouncing, translucent blue blob.

The slime—Rimuru—was happily bouncing left and right, exploring his surroundings with boundless curiosity.

At one moment, we saw him hop into a small underground lake, splashing around like a child experiencing water for the first time.

At another, he encountered his first monster, a lesser beast. We watched in amusement as he clumsily engaged in battle, absorbing it and mimicking its form.

There were times when the slime paused, tilting slightly as if lost in thought, before responding out loud to something unseen.

Velzard, who had been lazily watching, suddenly perked up. "Wait… who is he talking to?"

Ultima narrowed her eyes. "Yeah, it looks like he's having a full-blown conversation with someone… but there's no one there."

Testarossa smirked. "Either he's already gone insane, or there's something more to this."

I chuckled, reclining a little. "That's Great Sage."

Diablo raised an eyebrow. "Oh? That skill?"

I nodded. "It's one of his most important abilities. It's an advanced AI-like entity within him, guiding him, analyzing his actions, and offering advice. Right now, he's getting tutorials on how to use his body and abilities."

Velzard smirked. "So he basically has an instructor built into his soul?"

I nodded. "Pretty much."

Carrera chuckled. "He's got an in-game tutorial while we just threw Veldora in there and told him to improvise."

Days passed as we continued to watch. The slime continued to explore, fight, and grow stronger. He had even started mimicking human speech.

But Veldora…

We all watched as Veldora sat in his "prison," arms crossed, head tilted back against the illusionary barrier I had placed around him. His once confident smirk had faded into something resembling boredom.

"HAHAHA! This is getting annoying!" Veldora suddenly boomed, his voice echoing through the cave. But it was hollow. Even from the projection, we could tell he was losing patience.

Ultima snickered. "He's bored out of his mind."

Testarossa smirked. "He should've brought a book."

Velzard chuckled. "I told him he should've just kept reading."

Carrera leaned forward. "We should mess with him."

I smirked and shook my head. Instead, I activated Thought Communication.

"Veldora. Relax. He's close."

Veldora jerked upright, glancing around before realizing I was speaking in his mind.

"He is?" he responded through our link, excitement creeping into his voice.

"Yes. He should be able to sense you now. Give it a moment, and you'll see him soon."

Veldora exhaled, rolling his shoulders. "Finally! Time to get into character."

We all watched in amusement as Veldora cleared his throat and began… practicing his voice.

Veldora sat up straight, crossing his arms as he deepened his voice.

"WHO DARES APPROACH THE GREAT STORM DRAGON?!" he bellowed, his voice booming through the cave.

Then he frowned. "No, no. That's too scary."

He tried again, this time lowering his tone slightly.

"Ahhh, welcome, traveler. I am the mighty Veldora."

He shook his head. "Too calm."

Then he softened his voice, speaking as if he were a wise sage.

"Ah… I see destiny has brought us together, young one."

We all burst out laughing.

Carrera wiped away a tear. "He sounds like he's auditioning for a stage play."

Ultima was on the floor, clutching her stomach. "He's practicing different personalities!"

Diablo chuckled. "I must say, this is quite… entertaining."

Even Velzard, who usually had more composure, let out a soft laugh. "Veldora is hopeless."

I smirked and sent another message to him.

"Stop playing around. He's about to find you."

Veldora straightened immediately. "Alright, alright! Time to give the slime the best introduction ever!"

We leaned in closer, watching with eager anticipation as the slime finally began bouncing toward Veldora's illusionary prison.

The stage was set.

The real story was about to begin.