Complex sentence: Eiji's father and Sena's stepfather, who was thought to be dead during the Great Destruction, but it is revealed by both Daisy and Hiiragi that he is alive and the one who created Daisy.
Split into simpler sentences: Eiji's father and Sena's Stepfather who was thought to be dead during the great destruction. But is was revealed by both Daisy and Hiiragi that he is alive and the one who created Daisy.