King Mysidian is Sara's father and the ruling King of Mysidia. He appears quite cold and careless at the early points in this arc, we then find he's been hiding a dark secret. He chose his daughter over the entire country and caused pain, sorrow and chaos because of it, but he didn't care. He would do anything to keep this knowledge secret from his daughter who is completely unaware. 

He had a good heart and had wanted to create a world where everyone was equal, despite the complaints from the nobles. He gave the lower class citizens hope for life. So he devastated countless people when he changed his mind. 

He should have a bit more tired and worn kingly voice. Something royal but not overly noble, to show his true side of caring more for his family than his people.