The Greatest Assassin Gets Reincarnated in Tensura

In the highest chamber of the Watchtower of the Eternal City of Sleep, Arion stood by a grand, arched window, gazing down at the mist-laden streets below. The Eternal City never truly slept—whispers moved like the wind, unseen yet ever present, shifting the tides of power without the need for open conflict. It was here, in the heart of shadows and silence, that the real battles for dominion were waged.

Behind him, seated lazily on a couch surrounded by towering stacks of books, Veldora flipped through the pages of an ancient tome, completely absorbed in his own musings. The mighty dragon yawned, stretching like a cat, then turned his golden eyes toward Arion.

"You should've let me go," Veldora grumbled, tossing a book aside. "I could have shown them my greatness hahaha...hahaha...hahahaaa...! A single breath from me and those stubborn vampire nobles would have thrown themselves at Luminous's feet, begging to serve."

Arion chuckled, his voice barely above a whisper, but carrying a sharp edge. "Yes, and in the process, you would have turned it all into rubble, set the vampires into a frenzied panic, and possibly starting a war." He turned his gaze toward Veldora, amusement flickering in his crimson eyes. "Tell me, what's the point of a queen if there's no kingdom left to rule?"

Veldora huffed, crossing his arms. "Details, details… You're always so cautious."

Arion didn't respond. He simply turned back to the city below, his mind already ten steps ahead. Then, a knock came at the heavy doors. Without needing an invitation, they opened, revealing Diablo and Testarossa. Both knelt immediately, their expressions unreadable, their movements perfectly calculated.

"My lord," Diablo began, his voice smooth as silk. "Luminous has been successfully crowned as queen. The vampires now kneel before her."

"She put on quite the show," Testarossa added, smirking. "The illusion worked flawlessly. They saw her as invincible, godlike… just as we intended."

Arion turned to them, his gaze cool and piercing. He remained silent for a moment, letting the weight of the situation settle over them like an oppressive fog. Then, he spoke, each word deliberate.

"Good. The first phase is complete. Now… we move to stage two."

A slow, eerie smile crept onto his lips, the assassin in him awakening.

"We will control her from the shadows."

Diablo and Testarossa exchanged glances before nodding, awaiting orders. Arion stepped toward them, his voice lowering into something akin to a whisper, though the intensity in it made the air feel heavier.

"We will ensure Luminous remains in power, but she will not truly rule—we will. Every decision, every decree she makes, will be ours."

"How?" Testarossa asked, intrigued.

Arion's fingers brushed against the dagger strapped to his belt—a habit from his past life as an assassin. "Influence. Leverage. Manipulation. First, we isolate her."

Diablo's eyes gleamed with dark amusement. "Separate her from those she trusts?"

"Exactly." Arion nodded. "We will engineer small crises, betrayals, doubts. The nobles who resist her? We let them scheme… then expose their 'plots' at the right moment. Each time, it will be someone close to her, someone she thought she could trust."

Testarossa's lips curled into a wicked smile. "We break her trust… until the only ones she can rely on are us."

Arion's expression remained cold. "Yes. And once she depends on us for every move, every decision… we guide her choices, little by little. Make her think our will is her own."

Diablo's voice was practically dripping with pleasure. "Ah, the beauty of unseen control."

Arion's eyes darkened. "That's only the beginning. Next, we control the flow of information."

Testarossa raised an eyebrow. "You mean… feed her carefully chosen truths?"

Arion smirked. "Not just truths—half-truths, carefully placed lies, whispers of threats that don't exist. She will believe the world is moving exactly as we describe it. When she reacts, it will be in ways we've already anticipated."

Diablo chuckled, his amusement deepening. "A queen trapped inside a kingdom of illusion. And what of the nobles who still doubt her?"

Arion's voice became as cold as ice. "They will disappear. Quietly. Some will suffer 'accidents.' Others will be publicly executed for treason—evidence will be conveniently discovered."

Veldora, listening from the couch, chuckled. "You're really treating this like a game of chess, aren't you?"

Arion turned to him with a smirk. "A kingdom is always a chessboard, and its rulers are merely pieces… unless they learn to be the players."

Diablo placed a hand over his heart. "And when she finally sits atop her throne, alone, surrounded only by those who have shaped her mind into what we want… she will be the perfect queen. Our queen."

Testarossa exhaled in satisfaction. "This… is perfection."

Arion turned back toward the window, his eyes locked onto the distant horizon. The Eternal City below continued as it always had, oblivious to the silent war being waged from above.

"Proceed with precision," Arion ordered. "No mistakes. If we do this right… Luminous won't even realize she's merely a puppet on strings spun from shadows."

Diablo and Testarossa bowed deeply. "As you command, my lord."

And with that, they vanished into the darkness, leaving Arion alone with Veldora once more.

Veldora let out a lazy laugh. "You're quite the villain, aren't you?"

Arion's smirk never wavered. "No. Just a man who understands that the greatest power… is the one no one ever sees."

As the moon cast its pale glow over the city, the second phase of their grand deception had begun.

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Tucked away within an impenetrable veil of illusions and shifting darkness, the Eternal City of Sleep was both everywhere and nowhere—an invisible kingdom that no outsider could find unless invited. Unlike other strongholds that prided themselves on towering walls and impregnable gates, the city had no need for defenses.

Because no one knew where it was.

The streets of the city wound like veins through a living, breathing beast. Dark lanterns lined the cobbled roads, their eerie glow casting flickering shadows against towering structures of black stone and obsidian glass. The air thrummed with a quiet intensity, a city that never truly slept, yet functioned under an unspoken law of secrecy.

Despite its ominous reputation, it was a city of indulgence and luxury—if one knew where to look.

In the heart of the city lay The Whispering Bazaar, a vast market unlike any other in existence. Merchants from across dimensions set up stalls, peddling wares that could topple empires or shift the balance of power in an instant.

Blades forged from cursed stars, able to slice through reality itself.

Potions that could rewrite memories, bending minds to the will of the buyer.

Veils of invisibility, woven from the darkness between worlds, capable of rendering the wearer untraceable.

Sealed contracts of loyalty, unbreakable oaths that bound assassins to their masters until death.

Everything had a price, and in the Eternal City, the currency was more than just gold. Secrets were the most valuable trade, and those who walked through the Bazaar did not come simply to shop—they came to plot, to scheme, to build empires of their own in the shadows.

Beyond the marketplace, the city had its own kind of pleasure—a playground for killers, spies, and manipulators.

The Crimson Theater, where plays were performed with illusions so vivid that they blurred the line between reality and dream. Some plays told stories of war and betrayal. Others? They were executions in disguise—assassins eliminating targets mid-performance, their deaths mistaken for part of the show.

The Shadow Circuit, an underground arena where fighters—both demons and captured warriors—battled in silence, using only stealth and assassination techniques. It was not a contest of brute strength but of patience, deception, and precision. A single misstep meant death.

The Night Lotus Gardens, where nobles and rulers from across realms visited in secret, seeking forbidden pleasures and making dark deals over glasses of immortal wine.

Every venue was designed for pleasure, power, or death—and sometimes, all three at once.

What truly set the city apart, however, was its inhabitants.

Every man, woman, and child in the Eternal City was more than they appeared. A simple tavern keeper? A master of poisons who could end a king with a sip of wine. A street performer juggling knives? A killer trained to take a life mid-performance without breaking rhythm. The smiling merchant at the Bazaar? A spy who had infiltrated nations, selling more than just goods.

There were no ordinary citizens here.

Each individual, no matter how mundane they seemed, was a soldier of the shadows, ready to be called upon at any moment.

The Shadow Army was not merely an army—it was an invisible hand capable of reshaping the world.

They could infiltrate any kingdom, any nation. They could manipulate rulers, spark revolutions, or crush rebellions before they even began. If Arion willed it, entire empires could fall overnight, their leaders assassinated in their sleep, their cities surrendering before they even knew they were under attack.

This was the power of the Eternal City of Sleep—not a city of war, but a city that made war obsolete.

Because wars required armies.

Arion's army needed only whispers.

And whispers… ruled the world.