Setsuko Kageyama (蔭山 節子 Kageyama Setsuko): Doctor Kageyama's former wife and the mother of Shūichi. After Kageyama became Doctor Man, she left her husband and gave away their son Shūichi for adoption to the Nakamura family. 17 years later, the Bioman team and Shūichi stumble onto a letter she left behind, along with a video recording, which revealed Doctor Man's true identity. She never actually appears in the series besides a photograph of herself with Kageyama and Shūichi as an infant, and a voice-over while Shūichi reads her letter.