Eida Rossa cultivates a public image as an idol while secretly piloting the stealth-capable R-Daigun, a fifth mecha unit developed alongside the main Dancouga Nova machines. Equipped with combat systems like the Dan-Blade dual swords, Absolute Hurricane wind attack, and the Dan-Suteinga final attack, her actions as the R-Daigun's pilot initially place her in opposition to the Dancouga Nova team.

A romantic connection with Dancouga Nova pilot Johnny Burnette triggers her defection. She subsequently aligns with the Dragon's Hive organization, the same group backing the Dancouga Nova team, and the R-Daigun is reclaimed for their arsenal.

Her role expands significantly within Dragon's Hive. Piloting the R-Daigun alongside the Dancouga Nova enables their combination into the more powerful Dancouga Max God, granting enhanced flight capabilities and access to advanced weaponry like the Final Dancou-Cannon and Dancu-Dangaiken finishing attack. This integration marks her transition from antagonist to key ally, boosting the team's combat effectiveness.

Her dual life as a celebrity and mecha pilot remains defining. While her public idol persona features girlish pigtails, her piloting duties see her adopt different hairstyles, including wearing her hair down or under a helmet.