Azusa Ueda lives with her parents in the Ueda Apartment. She is Hayato Hayasugi's classmate and childhood friend, knowing him since kindergarten. Her personality is bratty, arrogant, and occasionally selfish or uncaring, often acting demanding and snooping around, traits which frequently annoy Hayato and other Team Ōmiya members. While expressing annoyance at Hayato's intense railway obsessions, she simultaneously respects his consistent understanding and acceptance of others' interests. Azusa actively pursues online fame as a popular elementary school YouTuber, though this pursuit sometimes strains her friendships. She remains committed to maintaining these relationships and assisting her friends when necessary, especially in critical situations.

A significant development occurs when she inadvertently records video footage of Shinkalion battles during a monster encounter, leading to her formal involvement with the Shinkansen Ultra Evolution Institute. This role culminates in her uploading a compilation of battle footage during the final confrontation against the Kitoralsus, a strategic act that galvanizes nationwide moral support for the pilots. Throughout the series, she holds the distinction of being the only non-pilot human member of Team Ōmiya. The Ueda household temporarily expands with the arrival of Seiryu after Episode 52 and Suzaku, who resides there from Episode 65 until the movie. Her surname connects to Ueda Station on the Hokuriku Shinkansen Line.