Known as the "Witch of the Cosmos," the female space pirate Emeraldas roams the universe aboard her airship-style spacecraft, the "Queen Emeraldas." No one knows why she travels through space. The story begins when a boy named Hiroshi Umino, who ventured into space in his handmade spacecraft, crashes into a canyon north of Argyle on Mars' moon, Deimos. Severely injured and taken to a hospital, Hiroshi escapes and returns to the crash site, where he encounters Emeraldas.