Chieri Sono

The daughter of a corporate CEO who introduces Nagisa and her friends to AKB when they are younger, and four years later runs away from her father to audition for AKB. Initially, Chieri displays a cool and serious personality, but later becomes more outgoing and friendly. She is very dedicated and passionate about AKB, and never hesitates to put herself at risk for the sake of her friends. Chieri is the first understudy to be accompanied by a Kirara, a small creature that glows whenever it detects the presence of idol radiance, though at first only seems to glow when Nagisa is with her, making Chieri feel inferior to Nagisa until the kirara finally glows for her alone in the last episode of the first season.

Yuuko Oshima sees Chieri as a rival for the Center Nova position, and after the New General Election, in which Chieri ranks 6th, Nagisa considers her a rival as well.