Machine Robo is a fan fiction, based on the 1982-1985 Bandai toyline of the same name, with no links to Tonka’s GoBots toyline (which consisted of reissued Machine Robo toys, and even inspired its own TV show, Challenge of The GoBots) or the Machine Robo anime that immediately followed. As such, Bike Robo, who was reissued in America as the villainous Cy-Kill, is now a good guy like all Machine Robos.
- Hotaru Tsukashiku: The main character, partnered with Bike Robo. He has a cheerful disposition, even after his father's disappearance.
- Keitaro Kiyakota: Hotaru's best friend. He is partnered with Battle Robo, though he does not agree with his simple crush-and-destroy philosophy. In fact, it rather disturbs him.
- Naoko Raputen: Hotaru's other friend. She is partnered with Blue Jet Robo. Things tend to get ro-man-tic between her and Hotaru, and just before they kiss, the scene is interrupted by either Keitaro or Bike Robo.
- Bike Robo: Think Bumblebee meets R2-D2. His alternate form is a very unrealistic motorcycle that Hotaru apparently thinks is real until he transforms. He is constantly getting himself in deep kakadoodoo, from getting kidnapped by a crazed biker to getting put in a boiling cauldron by island natives. Classic.