Sayo Kadoya is the unwitting secondary antagonist of All Riders Vs. Dai-Shocker. She is Tsukasa's younger sister and is protected by Nobuhiko Tsukikage. She is the one who allows for Dai-Shocker's travel between the A.R. Worlds, due to her possession of the Stone of the Earth. She is manipulated by Shadow Moon into hating Tsukasa and using the stone to become High Priestess Bishium. She eventually realized that she was being used and destroys the Stone of the Earth before making amends with Tsukasa.