Ryoma is the original leader of the Getter Team and the protagonist of many of the Getter Robo adaptions. In the original manga, he is portrayed as an extremely violent martial artist and the son of the "Dojo Destroyer" Ichigan Nagare.
Ryoma is first discovered by Professor Saotome's assistants when he breaks into a karate tournament to take revenge on them for disgracing his father's name. Impressed, Saotome follows this up by sending 3 hitmen after him as a test of his ability. Ryoma kills all three men, and in his weakened state is kidnapped by Saotome and taken to his research center. There he meets Saotome and his daughter and son, Michiru and Tatsuhito.
Soon after, the research institute is attacked by dinosaurs and many of the staff, including Tatsuhito are killed. Saotome tells Ryoma to pilot the incomplete Getter Robo in place of Tatsuhito against the attacking dinosaur empire. Ryoma succeeds at this, and continues to serve on the Getter Team as it's leader.