Katsuko Juuma is the daughter of Yakuza boos Oni Juuma. After her father's "death," she and her brother Kenji were left under the leadership of her brother Hirohito. He formed Juumasan Games, making millions producing video games. Katsuko worked for her brother and tried to talk sense into him about his grudge with the Green Hornet and Kato.
After her brothers death at the hands of the Hornet, she formed her own grudge, going after Kato's daughter Mulan.