Yuki Miya is an 18-year-old member of the idol group Mystery Kiss, alongside Rui Nikaido and Shiho Ichimura. She is characterized as the group's most responsible member and possesses an innocent personality. Her favorite food is karaage fried chicken. Her occasional naive remarks lead to conflicts with the group's manager, Yamamoto, causing her to express anger towards him.

Within Mystery Kiss, Yuki's responsible nature contrasts with Shiho Ichimura's aspirations for wealth stemming from an economically disadvantaged background. The idol group becomes centrally involved in a disappearance case that intersects with the main narrative. This case gradually unfolds connections to other characters and events across the storyline.

Yuki Miya grew up in circumstances that led her to pursue idol work. Her character development occurs through the group's collective experiences, including their management challenges and involvement in the mystery. The resolution of the disappearance case impacts her trajectory within the group's collective resolution.