Aoi Tomosato serves as support staff for the organization S.O.N.G., primarily operating from the command bridge of their submarine headquarters. She possesses dark blue hair and blue eyes, with some sources noting violet. Typically dressed in a blue jacket over a blue dress, black tights, and shoes, she stands 164 cm tall. Her name reflects its meaning: "Aoi" (written in hiragana) connects to the Japanese word for "blue" (ao), while "Tomosato" combines the kanji for "friend" (友) and "village" (里).

Tomosato maintains a calm demeanor and demonstrates trust in her colleagues. She collaborates closely with Fujitaka under Genjuro Kazanari’s leadership, providing operational support during missions. Her responsibilities include assisting Symphogear users like Hibiki Tachibana, such as explaining equipment like Durandal or offering refreshments after training. She also monitors emerging threats, handles information leaks, and speculates on strategic developments, including potential geopolitical interference during crises.

Her documented appearances occur primarily in Season 1 of the anime. In Episode 2, she offers a warm drink to Hibiki and participates in celebratory moments, later assisting in explaining the Noise threat during attacks. Episode 3 features her clarifying Durandal's significance and reacting with amusement to character interactions. By Episode 5, she provides Hibiki with further mission context, discussing geopolitical dynamics and Symphogear system development. In Episode 6, she comments on defense upgrades and speculates about external involvement in political assassinations before alarms signal new threats. She also appears in the manga adaptation (Chapter 4) and the mobile game *Senki Zesshō Symphogear XD Unlimited*.