Emeraldas has been compared many times to Captain Harlock, and the two have some similarities. They also know each other from the days of the Voice of Free Arcadia, when she fought side by side with him and Tochirou, the man who is their common bond. After the Ilumidus resistance, Emeraldas became much like Harlock, sailing the sea of stars and delivering justice in her own unique way.
Emeraldas is one of the few people who know the route of Count Mecha's Time Castle, and when her ship, the Queen Emereldas, appears next to the Galaxy Express, Tetsuro doesn't hesitate to get her attention. Emeraldas would've killed Tetsuro if it weren't for two things. First, Maetel (whom she also knows) is with him. Second, Tetsuro has Tochirou's hat and laser. She listens and then tells Tetsuro where the Time Castle will next appear: Trader's Fork, on the planet of Heavy Melder.
Some time after she leaves, she realizes something is happening on Heavy Melder, something that had to do with Tochirou. She arrives too late. Harlock tells her he's already dead. She leaves but later receives a message. It's from Tochirou, whose soul had been successfully integrated into the Arcadia. Learning that it was Tetsuro who had helped him, she realizes that she owes him a favor, and she proceeds to Andromeda, to repay the favor. She and Tetsuro will cross path a few more times.
Emeraldas is a very lonely soul, especially after the death of Tochirou. Her closest companion, like herself, is a wanderer. You see, the reason she and Maetel know each other...is because they're sisters. Emeraldas also has a daughter, Mayu, but she rarely sees her.