Ao Yodogawa is a 13-year-old junior high school student from Hiroshima Prefecture, representing the Chugoku region in a nationwide idol audition. Her athletic background includes national track and field competitions, fostering confidence in her running speed and a preference for constant movement over sedentary activities like studying, which she considers a weakness.

She embodies seriousness, politeness, and a refreshing demeanor. Ao openly admires her father, a former track and field athlete, as a significant influence. Her hobbies are muscle training, a carryover from her athletic career, and collecting sneakers that are both cute and practical for running. She expresses strong regional pride, supporting the Hiroshima Toyo Carp baseball team and actively promoting local attractions as part of her identity.

Within the competition, Ao joins the dance-focused subunit SPLASODA° with Hiromi Hamaguri, Nagisa Imau, and Nodoka Yagi. The subunit resolves creative differences by uniting their shared passion for carbonated drinks, fusing this theme into their choreography to forge a distinct performance style. SPLASODA° later becomes part of the larger idol group 9-tie, where Ao contributes to choreography development during the group's independent activities.

Physically, she has black hair, blue eyes, and a dark-skinned complexion, standing 158 cm tall and weighing 40 kg. Her name carries symbolism: "Ao" combines the characters for "meeting" (逢) and "life" (生), while "Yodogawa" translates to "pool river" (淀川). Her family includes her admired father and siblings named Kaya and Sami Yodogawa.

Her journey evolves from regional finalist to a member of a unit prioritizing collective success. This is demonstrated when all participants unanimously elect to disqualify themselves rather than remove fellow contestants, leading to their temporary removal before returning as a unified group.