Miria Akagi is an eleven-year-old idol affiliated with 346 Production. She was one of the initial eighty-four idols introduced in the Cinderella Girls project and appears in the short-form comedy series Cinderella Girls Theater Climax Season. She is categorized as a Passion-type idol, which reflects her energetic and cheerful demeanor. Born on April 14, she stands 140 centimeters tall and has a petite build. Her blood type is AB, and her primary hobby is chatting, which matches her talkative and sociable nature.

Her motivation to become an idol stems from a straightforward, childlike love for anything cute. She wants to wear cute outfits, sing cute songs, and dance cute dances, and she approaches her idol activities with enthusiasm and innocence. In the Climax Season episodes, she is often depicted in lighthearted, slice-of-life scenarios alongside other idols, such as being petted like a pet, showing her playful and affectionate side. Her role in the series is that of a young member who brings a sense of fun and spontaneity to the group interactions.

Key relationships include her interactions with fellow young idols from the U149 unit, such as Arisu Tachibana and Momoka Sakurai, as well as older idols featured in the anthology format of the Theater series. Her development across the Cinderella Girls franchise, including her appearances in the main Cinderella Girls anime and the U149 series, shows her gradually growing more confident in her performances while retaining her youthful joy. A notable trait is her ability to lighten the mood and connect with others through her friendly chatter, making her a natural team player in group activities.