シャドームーン
is Nobuhiko's younger sister, targeted a number of times by the High Priests as her life force could awaken Shadow Moon. At first she was not aware of Kohtaro being Black himself until his fight to save her from the clutches of Bilgenia. Once Nobuhiko emerges as Shadow Moon, she and Katsumi are terrified of his new appearance as she eagerly refuses his offer to join him in making a new world without violence. After the defeat of Black at the hands of Shadow Moon, she and Katsumi left Japan to start a new life abroad. However, when Katsumi heard the news about Black's revival, Kyoko attempts to return to Japan to see Kohtaro again.