The demon rolled over, it's body feeling sluggish and weak. Without a clue about the 'parasite' in his body, his demonic energy became lower and lower.

"What's wrong with me? Did someone secretly curse me?! Who dares?!" The demon shot into the skies and roared.

Like thunder, his roar covered countless kilometers into the Deep Abyss, however he inevitably annoyed others as they returned rage filled roars.

"Damn it! What's happening!? If I don't manage to recover, I'll just be waiting to die!" The demon said in anger, but who could he direct it to? 

A fellow demon perhaps? No, any one of the demons in the Deep Abyss was as strong, if not stronger than him in his peak state, much less this injured and hapless form.

Closing his eyes, he sent demonic energy through his body and found no obstruction, however his demonic energy thinned a little bit more.

"What is siphoning my power? Did some bastard use some parasite against me?! Don't let me find you!" After a moment's hesitation, he quickly flew back to his residence.

...

Sage could no longer be said to be a human. His skin was black and red, covered in scales, and a tail had sprouted from his back.

His eyes were all black, and his teeth sharp enough to penetrate refined steel. Sage didn't know how long he spent in the darkness, however he never once stopped in consuming blood.

If any high rank or middle rank demons saw him, they'd tremble in fear because Sage was currently a peak of low rank demon!

After being doused in demon blood, his body quickly became demonized, until there was no humanity left.

Sage could still think and recall everything, however his soul and aura was that of a demon. 

Without a shred of remorse, Sage angled his hand in a certain direction and smiled cruelly, his sharp teeth making him look ferocious!

...

The demon felt a chill, as if winter had come early, and then a heart wrenching pain came from his chest, as if his heart were being gouged out!

With a mournful wail, the demon started to froth at the mouth when a sharper pain burst forth, further incapacitating the demon!

Sage was as lucky, because despite him being a peak low ranked demon, his attacks inside the demon's body allowed him to damage the demon.

He could feel demonic energy coursing through his body, and a massive amount of demonic energy in the blood he was bathed in.

He had stabbed his sharp nails through the demon's heart, causing the latter to curse life as he struggled to allieve even a bit of pain.

Sage looked at the shining purple hue surrounding the pulsing heart and then with a wicked grin, he took a bite!

...

Demons normally hunted and killed each other, thus devouring souls and flesh of the other, however only a few demons ate the unlucky ones alive.

Sage currently ate with gusto, and the demon let out a final weak roar and then tumbled to the ground, black blood pouring from it's mouth. 

Soon a bubble appeared on the demon's body, and then another until a humanoid figure burst out of the demon's chest.

It was Sage, who looked down at the demon corpse with a smile, however he was currently 'greeting' every generation of this demon.

After being devoured and crushed, who wouldn't hold a grudge? Sage didn't even look at the bones in the surroundings and instead waved a hand.

When he became a demon, something he found to be impossible, he gained Soul Vision, which allowed him to see souls of the dead.

A small yet black soul gently floated into his scaled hands, and with a smooth motion, he placed the soul in his mouth and swallowed.

A stream of pure energy gently moved through his body, causing his demonic energy to condensed into a water like substance.

His body emitted cracks as his scales lost their luster and fell to the ground. Before he could panic, new scales grew in their place, more durable than before.

His height, which was around five foot eight directly increased to two meters, and with a scaly tail behind him, his dark black and red scales made him look ferocious.

"I survived! I freaking did it!" Sage wanted to cry in joy! Being in such darkness made him miserable, and without anyone to talk to, he felt like he was going insane!

'I wonder how much time I have left in this place... Maybe I can come back after becoming a Demon King?'

Sage had an unexpected harvest in the form of a trial, and he survived. The winner lives, and the loser dies.

Such a world with clear distinction made it easy for Sage. As long as he was strong enough, he could do anything he wanted.