Ryou Mukai is a student of Naraka High School and a member of Class 4. She is a childhood friend of Izuru Tomonaga. Ryou has pale skin and red eyes. She has long, blond hair that goes past her waist, which she gathers into twin ponytails with two identical clips that curve upwards and have spikes sticking out. She wears the standard Naraka High School uniform and her character is located at the middle of her collarbone.