Hero of His Own Opinion

Life is full of surprises that one would never expect, and I say this after living one life as a Demon King and another as an ordinary mortal. Now, a third life awaits me - one where I'll be the hero and fight on the side of justice in my first world. Ironic, isn't it? I was known as a bastard and a psycho, but now I'm supposed to be fighting for the good and for a brighter future? As a former Demon King, I have my own opinion.