Ryou and his brother, Takashi, are identical in appearance with only the length of their hair being different. Ryou was one of the few survivors of Earth who was later captured by the Galra Empire. He first appears after Princess Amue falls into a pit in an attempted execution by Sincline.
After meeting her, he assures her that the Galra Empire will be defeated by Golion and that his older brother was the pilot of the blue lion. Amue corrects him saying that her identical cousin Fala was piloting the blue lion instead and both conclude that his brother was murdered. Ryou then swears revenge against the Galra Empire on behalf of his deceased brother.
Afterwards, Ryou helps Amue escape the Galra planet after Sincline's attempts to draw her out by executing her people. Ryou urged her to accept and honor her people's self-sacrifice on behalf of her survival and escape through a Galra ship to land on Planet Heracles where he meets the rest of the Golion team.
Later, he and Amue return to the Galra planet to infiltrate the Beastmen invasion. After the Golion team invades the empire, he is taken hostage by Sincline in the final episode. As Sincline was being distracted by the space mice, Ryou takes the opportunity to kill Sincline in a murder-suicide tactic and dies in a fatal fall.
- Due to their identical appearance, both Shirogane brothers were combined into one character in the localization to censor out both of their deaths