The Greatest Assassin Gets Reincarnated in Tensura

As Rimuru Tempest continued to build his city, expanding the Jura Tempest Federation, the rest of the Cardinal World was teetering on the edge of chaos.

Demon Lords did not go to war.

Not like this.

Yet, Clayman, Frey, and Carrion were preparing for an all-out battle—an event that had never happened before.

The world watched in silence.

Far in Ruberios, the Holy Empire of Vampires, Demon Lord Luminous Valentine sat upon her throne of crimson velvet, tapping her nails against the armrest.

Her golden eyes gleamed in the dim candlelight of her grand cathedral.

"A Demon Lord war? This is troublesome."

She glanced at her most trusted aide, Louis, standing beside her.

"Raise the kingdom's defenses. We do not know how this will spread."

Louis bowed, his expression serious. "Understood, my lady."

Luminous turned toward Hinata Sakaguchi the leader of the holy knights.

"Hinata, I want you and the knights to remain on high alert. If this war spills over, we will not be caught off guard."

Hinata nodded, her piercing gaze reflecting determination. "If any Demon Lords think they can bring their mess here, they will regret it."

In the land of Titan's Domain, the colossal Demon Lord Draguel, watched the world with narrowed eyes.

War was coming.

His giant form sat upon his mountain throne, his massive fingers gripping the armrest with barely contained tension.

"Fools. Do they not realize what they are doing?" His voice was deep, like the rumbling of an earthquake.

His sons—Dagura, Laura, and Debura—stood before him, awaiting orders.

"Prepare the warriors. If this war drags on, the balance will be shattered."

His children bowed and left to carry out his command.

In the Dragon Kingdom, Demon Lord Milim Nava was grinning like a child on their birthday.

"A fight?! This is gonna be so much fun!!"

She sat upon the edge of her palace kicking her feet, giggling.

Her generals sighed in the background.

"Milim-sama… this is serious."

Milim ignored them, already thinking about how much destruction she could cause.

"I should totally join in! I haven't had a good fight in ages!"

Her trusted dragon, Midray, sighed. "Please, Milim-sama… do not just run in for fun."

She pouted.

"Boooo! But if Guy gets involved, I won't hold back!"

Her eyes sparkled with excitement.

Far in the Ice Continent, Demon Lord Guy Crimson sat in his castle of frozen ruins, watching the world shift.

His crimson eyes glowed.

He had not moved.

He had not acted.

But he was watching.

The moment things got out of hand…

He would step in.

But for now?

He smirked.

"Let's see how this plays out."

The nations of the world were panicking.

Kingdoms bolstered their defenses.

Nobles whispered in fear.

Armies were mobilized in secret.

The Eastern Empire—long silent—began fortifying its military bases.

The Western Holy Church, still watching Rimuru, was now more focused on the growing Demon Lord war.

Even the Dwarven Kingdom of Dwargon—led by King Gazel Dwargo—was watching closely.

This was no mere skirmish.

This was Demon Lords preparing for an all-out war.

And the Cardinal World trembled, waiting for the first strike.

----____----

The world held its breath.

Then, Clayman made the first move.

From the dark corridors of his lavish castle, the Marionette Master released his army of puppets, their soulless eyes glowing with a sinister light.

But this was not just a mindless army.

No.

At the helm of this marching force of destruction stood his five elite generals—The Five Fingers of Death.

Each one was a nightmare given form, bound by Clayman's twisted sorcery.

And as his army descended upon Carrion's territory, war had begun.

Alveron the Crimson Blade – A master swordsman, his blade drank the blood of fallen foes, growing sharper with every kill.

Selena the Marionette Queen – The mistress of illusions, able to control enemies like living dolls.

Vaelgor the Bone Reaper – A towering monster, wielding a scythe that severed souls from bodies.

Luthan the Shadow Piercer – A ghostly assassin who struck from the darkness, his daggers never missing their mark.

Dregor the Abyssal Warden – A hulking warrior in blackened armor, the shield of Clayman's army.

Their march into Carrion's lands was swift and brutal, cutting through the Beastmen's front lines with deadly precision.

Demon Lord Carrion, the Beast King, was not one to be outmaneuvered.

The moment Clayman's forces crossed into his domain, his beast warriors responded in kind.

His army, made up of battle-hardened warriors, howled into battle, their ferocity unmatched.

Leading them were his own elite warriors, the Three Beast Fangs:

Phobio, the Black Leopard – His speed made him untouchable, his claws could tear through steel.

Sufia, the White Tiger – A warrior whose martial arts rivaled even the strongest adventurers.

Grucius, the Crimson Wolf – A brilliant tactician whose strategies turned the tide of battle.

Carrion himself stood atop a cliff, his arms crossed, watching the battlefield with a savage grin.

"Let's see how well your puppets fare against real warriors, Clayman."

Then, with a single leap, he descended into battle himself.

As Carrion and Clayman's forces clashed, another force made its move.

From the skies, a mighty army of harpies and wyvern riders soared over the battlefield.

Demon Lord Frey, the Sky Queen, had entered the war.

Her kingdom's warriors, fast and deadly, rained destruction from above, striking down both armies with brutal efficiency.

Frey herself descended like a goddess of war, her golden wings gleaming in the sun, her whip crackling with lightning.

"You fools. You've both walked into my trap."

Her forces hit hard and fast, disrupting both Clayman's puppet forces and Carrion's beast warriors.

Now, the war was truly three-sided.

This was no longer just a battle.

It was a spectacle.

And the world was watching.

Every major kingdom had sent spies and informants to gather intelligence.

Dwargon's elite scouts reported the battle to King Gazel Dwargo.

The Western Nations' informants rushed to deliver updates to their leaders.

The Holy Church's hidden agents whispered reports to Luminous Valentine.

Even the Eastern Empire's shadow operatives were observing from the distance.

The war was a chessboard, and every ruler was adjusting their strategy.

Far from the battlefield, in the Eternal City of Nights, I sat upon my grand throne, surrounded by my lovers—Velzard, Testarossa, Ultima, and Carrera.

The glow of the magic screen reflected in our eyes as we watched the war unfold, sipping on fine demon wine.

Velzard, ever the calm and analytical, took a sip and smirked.

"Clayman is playing with fire. He's not as smart as he thinks."

Testarossa, with her icy elegance, crossed her legs and chuckled.

"Frey is the real winner here. She's manipulating both sides."

Ultima, always bloodthirsty, pouted.

"I wanna be there! Can't we join in and make it more fun?"

Carrera, with her usual wild grin, laughed.

"Let them destroy each other first. Then, we clean up whatever's left."

I leaned back in my seat, fingers tapping on the armrest.

Everything was going exactly as planned.

This war was not just a random conflict.

It was a game of shadows.

And I was the unseen hand pulling the strings.