The Greatest Assassin Gets Reincarnated in Tensura

Rouge sat on his throne in his crimson castle, a structure that stood at the heart of his territory—a fortress of fire and destruction. The walls of the castle burned with eternal flames, its towers stretching into the dark, abyssal sky of the Underworld.

The Primordial of Red, the King of the Underworld, the one who stood above all other demons… yet, he was bored.

With Noir gone, the Underworld felt empty, void of a challenge. The lesser demons cowered before him, and none dared to provoke his wrath. He leaned back, his piercing golden eyes staring at the ceiling.

"Maybe I should just fight the others," he muttered, his voice low and deep, filled with power.

Just as he considered going on a rampage, fate answered his boredom.

Far from Rouge's castle, Vert and Bleu had spent days refining their plan.

Bleu, the clever and calculated one, had carefully analyzed Rouge's fighting style. She knew his overwhelming strength, his brutal speed, and his destructive fire magic.

Vert, on the other hand, was the wild card. She didn't care for tactics—she only cared about chaos and destruction.

As they flew toward Rouge's territory, Bleu kept reminding Vert of the plan.

"Vert, listen. We have to stick to the plan. If we don't, we die."

Vert, flying ahead excitedly, grinned. "Yeah, yeah, I know! Don't worry."

Bleu sighed. She didn't believe her.

The moment they approached Rouge's domain, the sky darkened with ominous crimson flames swirling above the castle.

Two demon guards, clad in thick obsidian armor, stepped forward, their glowing red eyes fixed on the approaching Primordials.

"HOW DARE YOU ENTER OUR LORD'S TERRITORY WITHOUT PERMISSION?!" one of them roared.

Vert didn't even hesitate.

She blasted them to dust.

The explosion was instantaneous—a massive green energy blast consumed the guard, leaving behind nothing but ash.

Bleu froze in shock, her eyes widening.

"VERT! WHY?!" she screamed. "This was supposed to be a surprise attack!"

Vert crossed her arms, looking away. "I don't know what you're talking about."

Bleu pinched the bridge of her nose. "You idiot! He definitely felt that—"

Before she could finish, an immense wave of pressure crashed down on them.

A dark, fiery aura erupted from the castle, the air becoming thick with demonic energy. Bleu and Vert turned to see the castle doors explode outward, the flames licking the air as a tall figure stepped through the smoke.

Rouge.

His golden eyes gleamed with amusement, his long crimson hair flowing like an inferno. His body radiated pure, unfiltered dominance, his presence alone making the entire battlefield tremble.

"Heh… just what I was hoping for."

He cracked his knuckles, his grin widening.

Rouge walked toward them, his footsteps slow but deliberate.

"So… you two dare to disturb my peace… blow up my castle… and kill two of my subordinates?" His voice was calm, but laced with danger.

Bleu stepped forward, her demeanor collected, but she was tense.

"We came for a challenge, Rouge."

Vert grinned, stepping beside her. "Yeah! We're taking you down!"

Rouge raised an eyebrow, chuckling.

"Oh? And if I win?"

Bleu's expression darkened. She knew there was no going back now.

"…If you win, we serve you."

Rouge's grin widened.

"Good. Then if I lose, I will serve you."

Vert clapped her hands together. "GREAT! LET'S FIGHT!"

Rouge spread his arms, his fiery aura erupting, setting the battlefield ablaze.

"Come then. Show me what you've got."

Vert launched first.

Her emerald energy erupted, the sky above splitting apart as she crashed toward Rouge like a meteor.

Rouge didn't move.

The moment Vert's fist was about to connect, Rouge tilted his head slightly, dodging at the last second.

Vert's attack shattered the ground, sending shockwaves through the entire castle.

Rouge's hand shot forward, grabbing her by the face and slamming her into the ground with brutal force.

BOOM!

The impact created a massive crater, shaking the entire region.

Bleu used this moment to strike from behind.

She conjured massive spears of azure ice, launching them at Rouge with terrifying speed. Each spear was laced with deadly curses, designed to weaken his strength.

Rouge, without even turning, raised his hand, creating a barrier of crimson flames. The moment the spears touched the flames, they melted instantly.

Bleu's eyes narrowed. "Damn. His fire is too strong."

Vert burst out of the crater, her eyes burning with excitement.

"Hehe! That was awesome!"

Rouge smirked. "You're still standing? Good."

The real battle had begun.

The battlefield became a blur of destruction.

Rouge, Bleu, and Vert moved faster than the eye could track.

Each clash created explosions that could be seen across the Underworld.

Vert unleashed wild, chaotic energy blasts, her attacks tearing through the landscape.

Bleu weaved through the battle gracefully, casting complex spells that warped space and slowed time.

Rouge countered with pure, brute strength.

Each of his punches sent shockwaves, each of his kicks split the ground apart.

He grabbed Vert mid-air, spinning her at impossible speeds before launching her into a mountain.

Before Bleu could react, Rouge appeared behind her, his hand burning with hellfire.

He blasted her point-blank.

BOOM!

Bleu screamed, crashing into the ground, her robes scorched.

She barely had time to react before Rouge's fist came down like a meteor.

At the last moment, Vert intercepted, her wild energy crashing against Rouge's fire.

BOOM!

The impact shook the entire Underworld.

The battle lasted for hours.

But in the end… Rouge stood victorious.

Bleu and Vert were on their knees, panting, bloodied, exhausted.

Rouge stood before them, unshaken, unharmed, and completely dominant.

"You two fought well," he said, his voice deep and satisfied. "But I am still the strongest."

Bleu looked up, defeated. Vert, despite her exhaustion, grinned.

"Damn… you're strong."

Rouge extended his hand. "Swear loyalty to me."

There was a moment of silence.

Then, finally… Bleu and Vert bowed their heads.

"We pledge loyalty to you, Rouge."

Rouge smirked.

"Good. Now, let's have some fun."

-------

The grand hall of Jahil's castle was dimly illuminated by the flickering glow of countless candles, their eerie light casting elongated shadows across the cold stone floor. At the center of the vast chamber, thirty mages clad in dark ceremonial robes formed a perfect circle, their faces hidden beneath deep hoods. Ancient demonic symbols, etched in blood and glowing with malevolent energy, pulsated across the stone floor, forming an intricate summoning sigil.

The air was thick with the scent of burning incense and the metallic tang of blood, the scent of sacrifice.

At the far end of the hall, seated upon a towering obsidian throne adorned with skeletal carvings, was Jahil, ruler of the kingdom. His sharp, predatory eyes gleamed with anticipation, his lips curling into a wicked grin. With a mere lift of his hand, he gave the command.

The mages, their voices rising in a cacophony of unholy chants, began the summoning ritual. The castle trembled as the sigil radiated a blinding crimson light. The air itself seemed to rip apart, as a swirling vortex of darkness manifested within the center of the summoning circle. An overwhelming wave of abyssal energy flooded the room, suffocating and oppressive, bringing every mortal present to their knees. The slaves, bound and trembling, whimpered in terror, their fates sealed as mere offerings.

Meanwhile, in the depths of the Abyss, Rouge sat upon his own throne of dark stone, the flickering blue flames that adorned his chamber casting ominous shadows upon the walls. His crimson eyes gleamed with amusement as he sensed the call—an attempt to summon him to the Material World. He smirked, his lips curling into a smile laced with malice. "Interesting... this day just keeps getting better."

Turning his gaze to Bleu and Vert, his newly acquired subordinates, he spoke in a voice that resonated with authority. "Wait for me. This should be amusing."

Without hesitation, Rouge accepted the summoning. The abyssal flames around him flared, swallowing him whole in an explosion of dark energy.

A heartbeat later, Rouge materialized within the summoning circle in Jahil's castle, his towering presence instantly dominating the space. The oppressive aura of the demon sent shivers down the spines of everyone in the room. His dark crimson armor glowed faintly with an ethereal fire, his flowing black cloak billowing as if caught in an unseen tempest. His eyes, pools of abyssal fire, swept across the room with an expression of amusement and disdain.

A moment of heavy silence fell over the hall, the sheer power of his presence suffocating. Then, Jahil, the arrogant ruler, stepped forward, his voice laced with authority. "I am Jahil, ruler of this kingdom, and I offer you blood, power, and servitude. Now rise and serve me."

Rouge turned his gaze towards him, his smirk widening. His deep, chilling laughter echoed through the chamber, sending a ripple of unease among the gathered mages and guards. The slaves, their faces frozen in terror, dared not even breathe.

"You... want me to serve you?" Rouge's voice was smooth, yet carried an undertone of deadly amusement. "Do you even know who I am?"

Jahil's eyes narrowed, but his arrogance did not waver. "Yes, you are a strong demon, but you will serve me. Take these slaves as offerings and do my bidding."

Rouge tilted his head, his eyes gleaming with an unsettling hunger. "And what, pray tell, is your desire?"

Jahil smirked, his confidence unwavering. "There is a kingdom I want to conquer. Weaken them as much as possible so that we can take them over easily."

Rouge chuckled darkly, his voice reverberating through the room like a death knell. "Very well."

With a mere wave of his hand, the room was plunged into darkness, the air thick with an unnatural chill. A deafening, otherworldly whisper echoed through the hall as the souls of the bound slaves were wrenched from their bodies. Their agonized screams filled the air for but a fleeting moment before silence swallowed them whole. Their lifeless bodies collapsed to the ground, their eyes hollow, void of existence. The very essence of their souls was now his.

A collective gasp escaped from the mages and guards. Some took a step back in pure terror, their hands trembling. The ritual chamber, once merely ominous, now reeked of true horror.

Rouge's smirk deepened as he turned his gaze back to Jahil, his voice dripping with mockery. "Your offerings have been... accepted."

Then, with a final, chilling laugh, Rouge vanished into the shadows, leaving behind a hall filled with fear-stricken mortals and the lingering, suffocating scent of death.

Jahil, for the first time in his reign, felt the smallest trace of unease creep into his bones. He had summoned a monster. And monsters... do not serve the weak.