Earth's Saviour is the Heavenly Demon

The silence in the dimly lit room was thick and heavy, broken only by the faint creaks of the bed as Eren—no, Ashen—sat lost in thought. His mind raced like a tempest, methodically planning the first steps of his revenge against the predators who had preyed on this frail body. 

The humiliation Eren had endured in this cutthroat world, the whispered mockery and outright cruelty, burned within Ashen like fuel on a fire. But it wasn't just Eren's pain. 

Ashen's own memories, born of betrayal and slaughter, bled into the present, amplifying his rage. Together, they created a perfect storm of cold, calculating fury.

"They think they're untouchable," Ashen mused, his expression darkening. "They've never met someone like me."

His thoughts swirled with plans. How to break them. How to dismantle their lives piece by piece. He would exploit every weakness, every secret. 

In this world where wealth and influence reigned supreme, he would wield them like weapons, turning their own shields into swords. His mind was sharp, his resolve unyielding. The predators would soon find themselves prey.

But just as Ashen's thoughts were beginning to take form, a searing wave of heat surged through his body without warning.

Ashen's breath hitched, his hand instinctively clutching his chest. The sensation wasn't natural—his core temperature was rising with alarming speed, as if a furnace had been lit within him. 

The heat clawed at his insides, relentless and unforgiving. Sweat began to bead on his forehead, cascading down in rivulets as his skin flushed an angry crimson.

He staggered back, his body trembling violently under the onslaught. His legs buckled, and he barely managed to steady himself against the edge of the bed.

"What… is this?" he thought, gritting his teeth against the growing discomfort. His fingers dug into the fabric of the bed as though anchoring him to reality.

The heat wasn't just external—it radiated from deep within his very core, a molten inferno surging through him. His bones, already fractured from prior beatings, throbbed in protest, yet that pain paled in comparison to the fire consuming him from the inside out.

It was as though his very blood had been replaced with liquid magma.

Ashen's instincts, honed over decades as the Demon Lord, flared to life. Pain and shock were irrelevant. Survival was paramount. Forcing the agony into the recesses of his mind, he compelled his battered body into the lotus position.

His legs folded beneath him with a sharp crack from his still-healing bones, and his trembling hands rested shakily on his knees. 

Every movement sent jagged waves of pain through him, but Ashen's focus remained unbroken. His breathing grew shallow, but his mind sharpened with predatory precision.

He needed to act. And he needed to act now.

Ashen's eyes fluttered shut, and his breathing slowed as he drew his mind inward. He directed his consciousness to spread throughout his body, a practice so familiar it was second nature. Despite being in a foreign realm and occupying an unfamiliar vessel, the principles remained the same.

In Murim, this technique had been his lifeline, a skill that had saved him countless times from death's doorstep. Poisoned meals, ambushes, brutal injuries—this skill had allowed him to endure them all.

His consciousness brushed against every corner of his form—his bones, his muscles, his veins, and his organs. The sensation was strange, even unsettling. 

This body was weak, fragile, malnourished, and riddled with scars of past abuse. Yet, beneath the layers of frailty, Ashen sensed something else.

A faint glimmer of potential. A potential so profound it bordered on divinity.

Deeper still, Ashen found the source of the heat: an immense surge of energy coursing through his meridians. It was chaotic and wild, like a raging river threatening to burst its banks. His brow furrowed as he examined the pathways.

"Twisted meridians," Ashen thought grimly. The flow of energy within Eren's body was distorted, the channels warped and knotted as if they'd been neglected—or worse, deliberately left to wither—for years.

Yet amidst the chaos, there was an anomaly.

All of the dantian points—the spiritual reservoirs where energy was stored—were open.

Ashen's eyes snapped open, his face a mixture of shock and realization.

"This body… has the Heavenly Yang Constitution?" he murmured, his voice hoarse from the infernal heat ravaging him.

The Heavenly Yang Constitution was more than rare. It was mythical. Ashen had encountered it only once in his lifetime, and even then, it had been through ancient texts and secondhand accounts. 

This condition allowed for the accumulation of pure yang qi, making the body a vessel of unparalleled pure vitality and power.

He recalled tales of those born with this constitution, men who were revered—or hunted—for their innate abilities. Their bodies radiated vitality, drawing women to them like moths to a flame. 

Cultivators of this nature could reach unimaginable heights of power, provided they understood how to wield their gift.

Ashen's thoughts raced. "Why didn't Eren ever use this?"

The answer struck him like a blow.

Earth was no Murim. There were no cultivators here, no understanding of qi, meridians, or dantians. In this barren land of ignorance, the Heavenly Yang Constitution was no more than a dormant treasure, buried and forgotten.

A bitter laugh escaped Ashen's lips, though it was strained under the weight of his growing despair. "Lady Luck finally shines her light on me, only to laugh in my face."

Returning his focus inward, Ashen studied the chaotic energy ripping through his body. His mind moved swiftly, analyzing the root of the problem. The Heavenly Yang Constitution was undoubtedly a factor, but it wasn't the sole cause of the current catastrophe.

The true culprit was death itself.

When Eren had died, the natural barriers within his body—the blockages that had restrained his dantian points—were obliterated. This sudden release turned his body into a vessel, allowing the oversaturated mana of Earth's environment to flood in, unfiltered and unchecked, the moment Ashen revived it.

Ashen grimaced. In Murim, energy was cultivated deliberately and painstakingly. Here, the mana that now flooded his fragile vessel was a byproduct of Earth's impending Great Cataclysm, set to occur in just three years. 

The planet, once devoid of such power, had begun to leak mana from specific places, overloading the environment and triggering the destabilization that would eventually open gates to hell and otherworldly realms.

The body wasn't prepared. It was a dam unprepared for the deluge of a thousand rivers. And now, it was on the brink of collapse.

The heat surged again, and Ashen gasped as pain lanced through his chest. His breathing grew shallow, and dark spots danced across his vision.

"If I don't stop this…" he thought, panic creeping into his mind. "I'm going to die. Again."

His fists clenched, nails digging into his palms as he forced himself to remain calm. But calmness was a luxury, one he couldn't afford. Time was slipping away, and the growing storm within his body threatened to tear him apart from the inside out.

"Damn it," he growled, his voice trembling with fury and desperation. "I didn't claw my way back just to die a dog's death before I've even begun."

Not now. Not ever.