The prideful, third-year student council president of Uranohoshi Girls' Academy. She and her younger sister Ruby are part of a well-known and respected family. Dia also is a diehard fan of μ's and after she, Kanan, and Mari separated, she had been hiding her enthusiasm about school idols until she is convinced to join Aqours by Chika and the others. She is the origin of Aqours' name, passing it on to Chika's group from when she, Kanan, and Mari were school idols. She scolds and corrects the other members with her catchphrase "Bubbū desu wa!" (ブッブーですわ!), the Japanese onomatopoeia for an incorrect buzzer. her voice is hery average and plain like Hanamaru's, but in a lower pitch. please don't strain! :)