Nanae Fujieda works as Lieutenant Rei Hizuki's assistant at the Oppama Testing Facility, focusing on data collection and monitoring for the Sonic Diver units. She later transfers alongside the Sonic Diver team to the naval destroyer Koryu. Aboard the Koryu, she continues her data analysis duties while assuming additional responsibilities such as supply management and navigation. Her workload intensifies significantly on the destroyer, where she spends frequent long hours stationed on the bridge, leaving minimal time for herself.

Fujieda proves reliable, efficient, and exceptionally dedicated, willingly working extended hours without complaint. Despite this diligence, she maintains a reserved, shy, and unassuming demeanor, often avoiding attention or praise. Her physical description includes brown eyes, ear-length brown hair, a height of 1.55 meters, and the noted attribute of having the largest breasts among the female characters.

Born on an island, she has a younger sister named Hakashi. Fujieda shares a mutual childhood crush with Kurosawa Hiroharu, though details of this relationship remain sparse. Her deep commitment to her role stems from a personal motivation to be helpful to others; she finds fulfillment in supporting colleagues rather than seeking recognition. A recurring visual trait is her appearance in sponsor advertisements featured in every episode.