By Zephyria 
Prologue
A great Archmage reaching the 8th Circle. The owner of the ‘Black Mana Heart’ that encompasses all the Mana in the world. The savior who liberated the Demons oppressed for the ominousness of their red eyes….
The great King of Demons, ‘Mephisto’.
That is who I am.
And I had a grand goal: ‘to place the weak and wicked human race under my feet and rule them.’ Because I thought they deserved to be ruled.
There was one human bastard who annoyed me and chased after me all my life.
Perhaps the ill-fated relationship with that bastard was inevitable.
I was the Demon King who plunged the humans into terror and made them tremble in fear… and he was the hero who was praised for someday punishing me and saving the humans.
Whether he was trying to drive me to neurosis and death, he visited the Demon King’s castle every day and knocked on the door.
Annoyed by the sight of a lowly bug buzzing in front of me, I tried moving my residence to a quiet place, but with a more tenacious obsession than a demon, he eventually found my location and repeatedly showed his handsome face.
I wanted to kill him. So I tried to kill him.
But that wasn’t as easy as it sounded.
Whether it was just for show that he was called a hero, even I, who had reached the pinnacle in the field of Magic, found it quite overwhelming to face him seriously.
He was a guy who was on a different level from other human bastards who didn’t even know the ‘Ma’ of Magic. The most annoying part was that he had the same Black Mana as me.
There is no need for two perfect beings in this world.
‘Someday, I will definitely cut off that lifeline.’
But, ridiculously….
It was me who was about to have my lifeline cut off.
“Cough, ugh.”
With the groan I let out, blood gushed from my mouth. Shit. Really, I couldn’t help but curse.
Because this hero bastard who finally drove me to death was looking down at me with pitiful and loving eyes.
Moreover, my injury was a fatal one that wouldn’t be strange if I died right away, but the reason I hadn’t died yet was because this bastard was forcibly slowing down the progress of the injury.
He wasn’t going to let me die peacefully.
Crazy bastard.
That alone was enough to make me curse. The hero bastard went even further, disgustingly stroking my cheek with his blood-stained hand and even bringing his lips to my forehead.
“Just hold on a little longer, Meph… I will definitely….”
He was completely out of his mind.
I knew a long time ago that this bastard wasn’t normal somewhere… but why the hell is he rubbing his mouth there? Damn it. Is he pitying the enemy he’s killing with his own hands?
His actions were inconsistent and completely incomprehensible.
“Even in death… Gilbert, I will curse you.”
I hurled all sorts of curses at him.
“The day I am reincarnated, I will find you and cut off your head neatly…! Kill you and kill you again, and feed you to the Fiends… ugh.”
My stomach aches from the hole in it because I talked too much. I’m sweating like rain and bleeding so much that my head is dizzy. I could feel my consciousness fading away. Even if he slowed down the progress of the injury, I was steadily dying.
‘That I… would be defeated by a mere human bug. What a huge mistake. I can’t close my eyes with such an embarrassing mistake left behind.’
I slowly grabbed my chest and activated the Formula I had planted in the Mana Heart in advance for this kind of situation.
It was the ‘Soul Transference Formula’.
I was trying to abandon this dying body and move to a new body. That could be my reincarnation or an act of stealing someone else’s body.
I don’t know exactly what the result will be yet.
This was the first time I was using this Formula myself. But I was sure that I wouldn’t fail either way.
Of course.
It was an original Formula that I, who stood at the pinnacle of Magic, had researched and created myself, so there was no way it could fail, right?
“…Ah.”
Gilbert, who quickly noticed the change happening inside me, lowered his eyes. The bangs that fell down in disarray were casting a gloomy shadow on his face.
But it was already too late.
‘I will definitely avenge what made me like this.’
I struggled to raise the corners of my lips and glanced up at his face. And I immediately regretted that action.
“…Yeah. You promised to come find me, Meph.”
The darkness on his face was only temporary. He caressed my cheek with a smile as dazzling as if he had heard a confession, which made me feel really bad to be smiling so brightly while covered in my blood.
To be humiliated like this until the moment of death.
‘Damn it… if we meet again, I will definitely….’
Soon, darkness came.
I fell into a world of complete nothingness.