Marcie Shima, granddaughter of Earth Federation Captain Togo Shima, lives under the oppressive Seiren Federation occupation on the frontier world Limbos (also called Rinbos), a planet scarred by spacecraft wreckage. Her lineage connects her to Earth's military heritage.

She joins a group of young rebels resisting the Seiren. Relationships with Nabu Ancient and Aga Serene create interpersonal tensions, marked by a rivalry between the two males who often compete for her attention. Marcie rejects being treated as an object in this dynamic, expressing clear disapproval of their conflicts over "dating privileges" with her.

Her role intensifies when Nabu discovers technical data from the derelict 17th Space Battleship Yamato. Marcie participates in the covert construction of the 18th Yamato within a Seiren automated factory, stealing resources and technology for the ship's completion, demonstrating her commitment to liberation through high-risk operations.

Following the new Yamato's launch, Marcie joins its crew as it is drawn into renewed conflict. The discovery of information concerning the Goda super-civilization and its Monopole energy technology reignites war between Earth Federation remnants and the Seiren Federation. Her activities shift to space-based confrontations alongside the crew as they face escalating threats.