Hideki is a core member of the orphan group living at the Blue Sky orphanage with protagonist Takeshi. He stands out visually in his white football jersey, part of the color-coded team uniforms worn during Takeshi's organized American football games. Following the discovery of Takeshi's extraterrestrial origins, Hideki actively participates in defending against the Dazaan army. He operates support UFOs, coordinating cover fire in battle alongside fellow orphans Miki, Matsuo, and Goro. Their transformation sequence involves shouting "U! F! O!" to magically don uniforms before piloting their vehicles. Hideki maintains a consistent presence throughout the series' 47 episodes and the "Shadow World" movie adaptation, fulfilling his role within the core orphan group without significant individual development, a detailed personal backstory, or unique narrative arcs.