Emeraldas operates as a free space trader aboard her distinctive dirigible-styled spacecraft, the Queen Emeraldas. She enters the narrative following an emergency landing on occupied Earth after attempting a dangerous passage through the Flame Stream Prominence, also known as the "Owen Stanley Witch of Space," damaging her vessel. Her limited technical expertise requires assistance from Tochiro Oyama for repairs. This encounter forges an alliance with Captain Harlock and Tochiro. During a critical mission to rescue Harlock's lover, Maya, Emeraldas is captured by the occupying Illumidas forces. Imprisoned and facing execution alongside Maya, an Illumidas officer named Murigson fires his weapon during a rescue attempt by Tokargan rebel Zoll. The bullet grazes Emeraldas's face, leaving her iconic facial scar. Following these events and Maya's death, she abandons her neutral stance, joining Harlock and Tochiro aboard the newly revealed battleship Arcadia. She embraces the life of a space pirate and accepts exile from Earth alongside them. Beyond the film, Emeraldas features in her self-titled manga and a four-episode OVA series set chronologically later. In the OVA, she interacts with a young stowaway named Hiroshi Umino, demonstrating formidable combat skills in a gravity saber duel with Queen Baraluda. She presents Hiroshi with the Cosmo Dragoon pistol, previously owned by Tochiro, and references the existence of five such weapons across the Leijiverse. She also acknowledges Maetel as her sister within this storyline. Her appearances across various Leiji Matsumoto works exhibit significant continuity inconsistencies. The 1978 Galaxy Express 999 television series and related film depict her suffering a severe, ultimately fatal illness, confining her mostly to bed while a robot impersonator assumes her role; this illness is absent in her physically capable Queen Emeraldas OVA portrayal. The origin of her facial scar is retconned in the OVA, attributed to the sword duel with Queen Baraluda instead of the gunshot graze. Character relationships shift; the original 1978 Captain Harlock series identifies a younger brother, absent in all other media including the Queen Emeraldas manga and OVAs. She additionally appears in guest roles, cameos, or flashbacks within the 1978 Space Pirate Captain Harlock television series, the Galaxy Express 999 television series (including an hour-long special expanding her episode), Harlock Saga, and Cosmo Warrior Zero. Her youth and origin story are explored in Maetel Legend. Her final depicted chronological activity, presented in the Queen Emeraldas OVA, occurs five years after the events of the final Galaxy Express 999 film, providing further insight into her activities and character following the exile.