Roze hails from a Gishin Empire colony world, not Gishin itself, and initially pledges loyalty to Emperor Zuul. Serving as Prince Marg's attendant, her mission is to monitor and reinforce his brainwashing after Zuul kidnaps and manipulates him. She ensures Marg remains a compliant military leader against Earth while concealing her awareness of his conditioning.

Marg saving her from Zuul's wrath after a tactical error sparks genuine loyalty to him, complicating her mission. When she accidentally kills Marg during his return to his true self, she becomes consumed by guilt and embarks on a death-seeking vendetta against his brother, Takeru (Mars).

This destructive path shifts into a redemption arc fueled by disillusionment with Gishin's tyranny, unresolved conflicts with her resistance-member sister Rui, and witnessing the empire's brutality. She abandons her allegiance to Gishin, adopting the secret identity "The Rose Knight" to covertly protect Takeru from Zuul's forces without revealing herself.

Later, she openly joins Earth's defense forces and the Crasher Squad during the mission to confront Zuul on Gishin. Following Zuul's defeat, she chooses to remain on Gishin, dedicating herself to rebuilding the war-torn planet instead of returning to Earth or joining the Crasher Squad permanently.

Her relationship with Takeru evolves from adversarial to protective and supportive, especially as he faces life-threatening challenges in the final arc against Zuul. While not explicitly romantic, her concern for his survival and well-being consistently motivates her later actions.

The OVA *God Mars: The Untold Legend*, which recontextualizes Marg's backstory, implies her involvement in Marg's pre-brainwashing guerrilla activities and his subsequent capture by Zuul, though the OVA primarily explores Marg's perspective.