The Greatest Assassin Gets Reincarnated in Tensura

The Cardinal World had long suffered under the endless, thoughtless war between Guy Crimson, the Demon Lord of Ice, and Rudra Nam Ul Nasca, the Emperor of the Eastern Empire.

Both of them played their game—toppling nations, moving armies like chess pieces, and toying with entire civilizations as though they were mere entertainment.

For centuries, no one dared to stop them. No one could stop them.

Until now.

Arion had seen enough. It was tike to teach them a small lesson.

He would not fight them. He would not confront them.

Instead, he would make both of them his pawns.

And they would never know.

Step 1: Planting the Seeds of War

Arion knew the truth of manipulation: You don't force people to do what you want. You let them think it was their idea.

It started with whispers. Carefully placed.

In Rudra's Court – The Power of a Lie.

The grand imperial palace stood tall over the Eastern Empire, its golden towers reflecting the rising sun. Within its grand halls, whispers moved faster than the wind.

Tonight, Arion's agents played their part.

A minor noble, a man who thought himself insignificant, found himself approached by a cloaked figure. The figure placed a sealed document in his hands, its wax emblem carrying the unmistakable mark of an imperial informant.

The noble read it. His face went pale. His breath quickened.

"This… this can't be…" he stammered.

The document detailed an alarming claim: Guy Crimson's demons were amassing at the border, preparing to strike.

Was it true?

It didn't matter. It only had to be believed.

Within hours, the document reached Rudra's generals.

In Rudra's War Room....

The room was dimly lit, torches flickering as imperial commanders huddled over a massive war map.

"Demon forces have been spotted near our western territories," one general stated, his voice cold with calculation.

"Unacceptable. If we wait, they will strike first."

Rudra, the ever-calculating emperor, frowned. He was not a man who acted on impulse.

But then, another document appeared.

A survivor's report.

A soldier—half-dead and delirious—claimed that a demon attack had already taken place in a border village. The man had seen his comrades burned alive. He swore by his life that the demons were behind it.

(What the soldier didn't know was that he had never been attacked. His memories had been carefully rewritten by one of Arion's shadow agents.)

Rudra's hands clenched into fists.

His nation had suffered a demon attack. That was unforgivable.

He turned to his generals. "Prepare the army."

Arion watched from the shadows.

Phase one: complete.

In Guy's Territory – The Demon's Wrath...

Deep within the frozen fortress of the Ice Continent, Guy Crimson sat upon his throne. His subordinate Rain and Misery kneeled followed by a demon duke before him, their voices rising in anger.

"The Empire is planning to strike us first," the Demon Duke growled. "We must act before they do."

Guy's crimson eyes burned. "And what proof do we have?"

That was when a sealed letter appeared before him—delivered by a lower-ranking demon, who had intercepted it from a "spy."

The letter contained imperial orders—signed by Rudra himself—outlining an invasion of demon territory.

The signature was flawless. The details were precise.

Only one problem: Rudra had never written it.

It was a forgery so perfect that even Guy Crimson, the Primordial Demon lord, believed it.

His lips curled into a grin.

"That arrogant bastard."

His aura surged, chilling the very air.

"If war is what he wants… then war is what he'll get."

Arion spy, hidden in the shadows of the ice palace, smiled.

Phase two: complete.

Step 2: The First Blow – A War Without a Cause.

Now, it was time for the final push.

Arion didn't need to start the war.

He only needed them to believe it had already begun.

The Assassination That Never Happened

Within Rudra's empire, a powerful imperial general—one of his most trusted men—was found dead in his chambers.

His throat had been slit with an unnatural blade, his body frozen solid.

The message was clear: Guy Crimson's demons had done this.

Of course, no demon had actually been there.

The assassin? One of Arion's own shadows. The blade? Infused with magic that mimicked Velzard's ice.

Rudra's fury exploded. This was war.

The Raid That Wasn't

At the same time, in the western reaches of Guy's domain, a key demon-controlled part of his enormous castle erupted into flames.

The attackers? Imperial soldiers, witnesses claimed.

But the truth?

The entire event was orchestrated by Arion's spies.

No imperial soldier had actually been there. The survivors were simply made to believe they had seen Rudra's forces.

Guy, furious beyond reason, did not hesitate.

He mobilized his armies.

Step 3: The Inevitable War.

By the time Guy Crimson and Rudra stood face to face on the battlefield, they were already beyond reason.

They did not question.

They did not hesitate.

They simply hated each other.

The sky darkened over the battlefield.

On one side, Rudra's Imperial Army, lined in perfect formation, their banners stretching across the horizon.

On the other, Guy's Demon Legions, the air around them crackling with malevolent energy.

Rudra's gaze burned with cold fury.

"You killed my general."

Guy's lips curled into a snarl.

"And you burned my castle."

Neither knew that neither crime had truly been committed.

But they believed it.

That was all that mattered.

A single breath passed.

Then—the world erupted into war.

Far away, hidden in the deepest shadows, Arion watched.

Neither Guy nor Rudra would ever know that they had been led here—not by fate, not by strategy, but by whispers and manipulation carefully placed in their ears.

This was Arion's true power.

The perfect war was not one created by brute force.

It was one where both sides willingly destroyed themselves, believing they had no choice.

It had always been Arion's game.

And he had already won.....

Yet, despite their immense power, the battle did not have a clear victor. Both sides continued to push forward, neither willing to surrender.

But as the bodies piled up, the weight of the carnage became undeniable.

Rudra's forces, though vast, were dwindling. Guy's demonic army, though powerful, could not sustain endless losses. The sheer scale of death and destruction finally forced both rulers to pause.

A moment of silence stretched between them, as they stood among the corpses of their fallen warriors.

"...Enough." Rudra's voice was heavy, not with defeat, but with realization.

Guy exhaled, shaking his head. "Tch. Took you long enough to see the obvious." He turned, surveying the battlefield. "What a waste."

They both knew it—neither could truly win without obliterating everything in their path. This was no longer war—it was senseless slaughter.

Arion.

Cloaked in shadows, his glowing eyes pierced through the void, watching as the two most powerful rulers of the age finally stopped their pointless war.

A slow, knowing smile crept onto his lips. "That will teach them."

This was exactly as he had planned—to force both sides into a brutal conflict so devastating that they would be forced to reconsider their ambitions.

Arion chuckled softly. "Even the mightiest kings need to learn that power without restraint leads only to ruin."

The game was moving exactly as he intended. And soon, the true lesson would begin.