|This article is about a/an ally in Choudenshi Bioman.|
Shūichi Kageyama (蔭山 秀一 Kageyama Shūichi): Thinking himself an orphan, named Kōichi Nakamura (中村 公一 Nakamura Kōichi), he learns he is in reality Shūichi Kageyama, the son of Doctor Man and basis of Prince's design. At first, Doctor Man tries to get him to join Gear, but Shūichi rejects Doctor Man after hearing his mother's words especially his evil ambitions he had made. Eventually, Shūichi finds and joins Professor Shibata when he tries to test his conscience circuit towards Miki until her sacrifice to destroy the Satan Megas. Shuichi keeps Mika's bola tie as a remembrance to her. Later, he helps the Bioman ultimately defeat Gear and trying to rescue Professor Shibata as a disguised Prince. He manages to convince Doctor Man to help them stop the bomb that could destroy the whole Earth through the use of human emotions by using his family picture with himself as a baby, his mother and Doctor Man's human form, Hideo Kageyama. (Played actor by Hidenori Iura) In the Philippine Dub, his English Dubbed name is Sonny and is voiced by Earl Palma.