The Grandson of the Demon King

A boy who was despised in the countryside walked all the way to the big city and discovered that his grandfather was the strongest man in the world. The strange words he had recited were actually powerful magic spells. The boy was inexplicably involved in wars between various races. In order to help the human race become the final winner, he had to use his grandfather's name to persuade girls from other races to become his subordinates and fight for a just cause.