Mihiro Terahara is a member of the Sirius theater troupe and an actor within the group. She is described as having a calm and composed demeanor, often serving as a steady, older-sister-like presence among her peers. Mihiro possesses a clear understanding of both the prestige of Sirius and the strict training regimen that the troupe demands. In the story, she fulfills a supporting role, contributing to the group's performances and maintaining a level-headed atmosphere. Her motivations are tied to her commitment to the troupe, though specific personal ambitions are not emphasized. Her key relationships are primarily with fellow Sirius members, but no individual connections are singled out. Mihiro does not undergo significant personal development over the course of the narrative, remaining a consistent and reliable figure. She does not showcase any extraordinary abilities; her role is grounded in standard acting skills and her supportive presence within the company.