Eren closed his eyes.
The principle behind the forbidden technique was simple—at least in theory. All he had to do was simultaneously reverse the flow of mana between his mana core and mana pool. But, a single second's delay in reversing one of the mana valves, however, would mean instant mana pool combustion…
So, perhaps it wasn't that simple after all.
But he had done it. This wasn't the first time he had played the dangerous game of tampering with his mana core in a desperate bid to force an awakening. And somehow, in that moment when all hope seemed lost, he had managed to reverse the flow—without killing himself in the process.
However, the reversal was only the first step. The second was far more dangerous: forcing his mana core to absorb atmospheric mana. That was something unheard of in this world. Absorbing atmospheric mana was a feat only attainable at the highest levels of power, a level far beyond his reach—one he could never hope to attain in his lifetime due to his meager talent. Even the protagonist, with all his plot armor, would have had a slim chance of surviving the absorption process.
And yet, Eren had done it.
Somehow.
Even now, he still couldn't quite believe he had pulled it off.
Humans were born with a unique ability—their bodies naturally produced mana. The mana core, the central processing unit of this energy, converted aura pulses—subtle waves released by the heart after absorbing excess surrounding energy. The core then picks up these pulses and refines them, producing mana unique to the bearer of the mana core.
The difference between the strong and the weak ultimately boiled down to two things: the size of the mana pool and purity of the mana core. A purer mana core led to faster expansion of the mana pool. A larger mana pool meant broader mana veins, allowing more efficient energy output.
Eren's problem?
He had the smallest mana pool possible. So utterly unremarkable that his family didn't even bother investing in him. Instead, they focused their attention on his step-siblings and more promising relatives, casting him aside as worthless.
That was who he was supposed to be.
Until it happened.
His mana core, forced to absorb atmospheric mana prematurely, had reacted violently. His mana valves, connecting directly to his mana pool, had expanded far beyond their natural limits. The impurities from the unprocessed mana flooded his system, forcing his mana pool to grow at a dangerously rapid pace—too fast, too unstable, too risky. But once the process had begun, there was no stopping it.
And yet, what truly baffled him…
Was that the entire ordeal had been utterly, completely—
Painless.
He didn't even feel pain—when, theoretically, this was supposed to be hell.
"Damn it…" His body trembled violently as he struggled to rearrange his mana valves.
Then—
"Argh!"
His back slammed into the mirror, his chest exploding with raw, searing agony. He gasped, trying to force himself upright, but his body refused to obey. Every nerve burned as if set ablaze.
"Ugh…" He groaned through clenched teeth, the excruciating pain intensifying.
"What the fuck… is happening?"
He slammed his forehead against the mirror. The glass cracked beneath the impact, a web of fractures spreading outward like the breaking of his own sanity.
"AHHHHHHHH!"
His knees buckled. He barely managed to grip the sink's edge, fingers clawing for stability. But it was useless. The mana inside him twisted in unnatural ways—each attempt to reverse the flow only made it worse. His valves tangled, the energy surging wildly, piling up in a single, volatile point.
"ARGHHHHHHHH!"
His eyes shot open, just in time to witness the transformation unfolding before him.
The last remnants of blue in his irises were swallowed whole by a glowing, amethyst hue. His once-gray hair bled into black—inky darkness creeping downward, spreading like ink spilled on parchment.
His body convulsed. His screams grew louder, more desperate. He tried. And tried. Failed. And failed again.
"Help…" The word tore from his throat, raw and broken, before his legs gave out.
He collapsed. Darkness crept in, swallowing his vision whole.
Perhaps… this was it.
Perhaps this was his final stop.
Death's door.