The Greatest Assassin Gets Reincarnated in Tensura

The night air was thick with the scent of blood and burning flesh. The remnants of battle hung in the atmosphere like a ghostly whisper, and in the distance, he could feel it—a powerful aura radiating malice and destruction.

He narrowed his eyes, scanning the area. His senses, sharper than ever after integrating his past self, locked onto a presence not too far away.

"Lara," he spoke in his mind.

"Yes?"

A grin formed on his lips. "We just found our first true test subject."

"I assume you are referring to the high demon roughly 800 meters ahead. From my analysis, he belongs to the red lineage—a warrior caste of demons known for their brute strength and fiery affinity. Proceed with caution."

"Caution?" he chuckled. "No, Lara. I want to see how deep my new skills run. Let's approach him… without him noticing."

Without another word, he propelled himself forward, his movement smooth, precise. He no longer wasted energy flying in a straight line; instead, he wove through the terrain, using natural cover, keeping his presence non-existent. Every movement was calculated, refined.

As he neared his target, he found himself perched behind a massive rock, shrouded in darkness.

Peering from his cover, he took in the sight before him.

The high demon stood at nearly eight feet tall, his skin a deep crimson with pulsating black veins running across his arms and chest. His eyes burned like molten lava, and a pair of jagged horns jutted from his forehead. His aura was suffocating, filled with sheer destructive force.

But what intrigued him the most was the carnage before him.

Lesser demons—weak, insignificant creatures—had been utterly obliterated. Their charred corpses littered the battlefield, some still smoldering, their twisted forms writhing in agony before finally turning to ash.

The high demon stood amidst the destruction, watching with amusement as the last of the lesser demons tried to crawl away.

With a wicked grin, the red demon raised his clawed hand.

*FWOOSH!*

A wave of crimson flames erupted from his palm, engulfing the pathetic creature in an instant. The agonized scream lasted only a moment before silence took its place.

The high demon scoffed. "Weaklings."

Hidden behind the rock, he watched patiently. Every fiber of his being screamed to move—to test his skills, to strike—but he knew better. The true essence of an assassin was patience.

His breath slowed. His aura vanished entirely.

Using Shadow Step, he blended with the darkness itself, moving like a ghost through the battlefield. His Stealth Mastery ensured that not even the wind carried his presence.

Feet gliding across the ashen ground, he closed the distance.

Fifty feet.

Thirty feet.

Twenty feet.

Nothing.

The high demon, a warrior of great strength, had no idea he was being hunted.

He felt a rush of satisfaction. The old him—the one before integrating his assassin self—would have never achieved this level of stealth. But now? Now, he had become the perfect predator.

The high demon stretched his wings, preparing to leave.

"Not so fast."

Like lightning, he struck.

His body moved before thought.

One moment, he was in the shadows. The next—he was behind his prey.

Using *Phantom Blade*, he manifested a dagger of pure condensed energy in his hand. With an assassin's precision, he plunged it forward—aiming for the base of the demon's spine, a weak point where even the toughest demons had trouble reinforcing their defenses.

*SHHHLKT!*

The blade found its mark.

The high demon's body jerked violently. His wings spasmed, and his molten eyes widened in shock.

"Wha—"

Before he could react, a second dagger materialized in his other hand. Without hesitation, he slashed across the high demon's Achilles tendon, severing his ability to move.

*SCHLICK!*

The demon let out a guttural roar, staggering forward as his legs buckled beneath him.

"What—Who dares?!" he snarled, spinning wildly.

But by the time he turned—his attacker was gone.

He stood ten feet away, hidden in the shadows once more, watching as the high demon clutched his wounded back, his flaming aura flaring with rage.

"Lara," he whispered in his mind.

"Report."

"Direct hit. The spinal strike disrupted his mana flow for approximately seven seconds. The Achilles cut was effective, but his natural regeneration is already beginning to repair it. His power output has risen by 25%—he is angry."

A smirk tugged at his lips.

"Good. Let's see how he fights when he's the prey."

The high demon's burning gaze scanned the area, his nostrils flaring.

"Coward! Show yourself!" he bellowed, his voice shaking the battlefield.

But there was no answer.

No movement.

Nothing.

For the first time, the high demon felt something unfamiliar creeping into his bones—uncertainty.

And in the silence, the assassin smiled.

This was going to be fun.

The high demon snarled, his molten eyes scanning the darkened battlefield, but he saw nothing.

His breathing was ragged, a mix of fury and pain. His spine throbbed from the surprise attack, his Achilles tendon burned from being severed, and worst of all—he couldn't sense his attacker at all.

"Where are you, coward?!" he roared, his voice shaking the very ground beneath him.

Silence.

Then—a whisper in the wind.

"Right behind you."

The high demon's eyes widened, but before he could react—

THWACK!

A brutal kick landed at the base of his skull, sending him sprawling forward. He crashed onto the ground, the impact sending debris flying.

Snarling, he flipped back onto his feet, summoning a ball of searing crimson flames in his palm.

"Enough of this!"

With a furious roar, he unleashed a barrage of fireballs, each one burning hotter than magma. They exploded across the battlefield, turning the area into a blazing inferno.

But there was still no sign of his opponent.

His breathing quickened.

"Damn it! Where is he?!"

Suddenly, he heard a whistle—faint, mocking.

To his left.

He spun and swung his clawed hand with all his might—only to slash through empty air.

"Too slow."

Pain erupted in his ribcage as a dagger slashed across his side.

"You—!" He swung again, but his attacker was already gone.

Another cut, this time across his thigh.

Then another, carving into his shoulder.

"Tch! This bastard!"

He roared, his demonic aura erupting outward in a wave of destructive energy, shattering the ground beneath him. The sheer force of it sent the nearby flames flickering wildly.

"Try hiding from this!"

A sphere of pure fire ignited in his hand, crackling with unstable energy. With a snarl, he slammed it into the ground—causing a massive explosion that tore through the battlefield.

BOOM!

The shockwave sent shockwaves of heat across the area, turning the very air into something unbearable.

Smoke and dust filled the space around him.

He panted, his burning eyes scanning for any sign of movement.

Nothing.

Then, out of the smoke, a voice whispered.

"Nice try."

His body froze.

SHUNK!

A blade pierced straight through his stomach from behind.

"Gah—!"

The high demon staggered forward, blood dripping from his mouth. He turned, fury and disbelief in his gaze.

And there he was—his attacker, standing before him, his expression calm, calculating.

"I've learned everything I need to know." His voice was cold.

The high demon bared his fangs. "You… damn… rat!"

A desperate move—he reached forward, attempting to grab his attacker—

But the assassin simply stepped back, out of range, his dagger still dripping with blood.

"You rely too much on your power," he said flatly. "Brute force won't help if you can't hit your target."

The high demon's body trembled with rage.

"I will burn you alive!"

With a roar, his body erupted into crimson flames. His form grew bulkier, his horns extended, and his aura flared wildly. The ground beneath him melted from the sheer heat.

"I'll show you the true power of the red lineage!"

A massive firestorm formed around him, swirling with chaotic energy.

But his attacker remained unfazed.

In fact—he smirked.

"Let's see what you've got."

As the high demon unleashed his inferno, his opponent activated one of his most dangerous abilities—

Sovereign Devourer.

A dark vortex formed in his palm, invisible to the high demon but felt nonetheless.

The flames surged forward—only to be sucked into the void.

The high demon's eyes widened.

"Wha—?"

His attack was being devoured.

The swirling black energy absorbed the firestorm completely, shrinking it down into nothingness.

His attacker exhaled slowly. He could feel the energy coursing through his veins—the raw power of the red lineage now becoming part of him.

"Not bad," he mused, his own hand igniting in the same crimson fire.

The high demon staggered backward.

"Impossible…"

His own power—his birthright—being wielded by his enemy?

"You…" The high demon's voice trembled.

His opponent took a slow step forward.

"Now it's my turn."

And with that—he vanished.

A blur of motion. A flash of fire.

The last thing the high demon saw was a burning blade plunging into his chest.

And then—darkness.