Mirei Minami is one of the core characters in the series, voiced by Yu Serizawa from the group i☆Ris. She's a seventh grader at Paprika Academy and represents the pop idol type of the group, though not much has been revealed about her backstory yet.
In PriPara, Mirei sports lemon yellow hair styled into two buns at the top that look like cat ears, held with blue and yellow ribbons, and she has blue eyes. In her regular life, though, she's got brown hair in a high ponytail, brown eyes, and wears glasses—a pretty different look.
She's genuinely smart and a puzzle whiz, which landed her the role of disciplinary committee captain at school. Her catchphrases are "Keisandouri" (basically "just as calculated") and "Keisangai" ("miscalculated"), and she tends to tack "pri" onto the end of sentences. Fans often note that she seems to admire Cosmos.
Interestingly, Mirei is the only PriPara character who shares a voice actress with someone from Pretty Rhythm: Rainbow Live—Yu Serizawa also voiced Ann Fukuhara. Her name itself comes from the third note of the solfège scale.
Content compiled by AnimeList.moe from publicly available sources.