Princess Emeralda rules the Sanborn duchy in a past era. She is the human predecessor of the future cyborg Armaroid Lady, Cobra's companion. When Cobra accidentally travels back in time, he finds Emeralda embroiled in political turmoil. Political adversaries, Lord Gilos and his bodyguard Manidou, threaten her reign with assassination attempts, creating the central conflict during Cobra's time in the past.

Emeralda and Cobra develop a romantic connection. This contrasts with the typically platonic or professional dynamic between Cobra and the present-day Armaroid Lady in other narratives. Their past relationship defines Emeralda.

A pivotal, irreversible transformation from human princess to the Armaroid Lady cyborg marks Emeralda's fate. Cobra's journey to the past is directly motivated by the future Armaroid Lady's deterioration, linking Emeralda's existence to the cyborg's future condition.