Dia is a very refined and mature young woman who tends to speak in a formal style of Japanese. She regards all of her friends with politeness, referring to each of them as "-san." Hardworking and a bit of a perfectionist, Dia dislikes it when things are done sloppily or incorrectly. She is also very meticulous regarding small details, as far as going on tirades regarding the unorthodox reading of certain Kanji

Though always trying to remain calm and collected, she tends to become overly zealous when school idols are involved, as she is very passionate about the subject. She wants nothing less than total success for Aqours, and constantly pushes herself and her friends to be the best they can possibly be in order to achieve their goals. Despite being short-tempered and brash at times, Dia genuinely cares for each of her friends, particularly her younger sister Ruby, whom she is very protective and nurturing of. She has a habit of scratching her mole whenever she is telling a lie.

Her voice is medium.