I wanted to be a hero but why did I got reincarnated as a demon lord ?

A man that wanted to save everyone got reincarnated as a demon world in a fucked up world. He then decided to change it with his own influence and power, to bring the world as the same as the modern world that he came from. Will he create a better world? or will he succumb to the devil inside of him? The goal of me putting the story here is to one day adopted them into manga (a form of Japanese comic). I would be happy if you criticize my writings, but don't expect me to really change it, because the main focus is just to save my idea somewhere that will not get infected with a computer virus nor accidentally deleted by myself when I clean my hard disk. Enjoy reading