The Old Days Came Back, but I Became a Magical Girl

I, the only ruler in human history, the incarnation of the past. When I woke up again after sleeping for two hundred years to save mankind, there was no place for me in the new world. My former colleagues killed my mentor and the world I was familiar with, robbed me of the glory I deserved, and even claimed to be God. But they don't know that I will return again five hundred years later. Then take the form of a magical girl to beat up and correct the world!