Yoko Shimomura would later become a well-established video game composer through her work on the "Kingdom Hearts" series. Additional arrangements were done by Shigeo Tamaru. Despite her previous work as lead composer on "Super Mario RPG", "Parasite Eve" became her breakout project and garnered her international fame. During her work on "Parasite Eve", Shimomura spent time in America, which was where much of the game's staff came from. Because of this, Shimomura remembered the game as her most challenging project. She wanted the music to be experimental, not falling into ambient or techno classifications. One of her main goals was to create something "inorganic" and recognizable as a product of Square. Until "Parasite Eve", Shimomura had written music in a straightforward manner that reflected her then-current state of mind, but this time she restrained herself and took a more "emotionless" approach. She felt that this would best represent the game's atmosphere and Aya's stoic attitude. Ultimately, she felt that "Parasite Eve" was an experimental work in many ways. Due to its prevalence in the story, Shimomura used opera music, but as typical opera music did not translate well into battle themes, Shimomura added different rhythms: these rhythms were inspired when some of the game's American staff took her to a nightclub and she heard the background music there. The music recording took place at the Andora Studios in Los Angeles.