Jun is a student at the prestigious music school overseen by the manager Akiba Kisaragi, where she is selected as a member of the elite Class S. Her full name is Jun Morimura. Central to her personality is a belief that music and performing are fundamentally about competition. This philosophy leads her to maintain an aloof and superior attitude, intentionally keeping her distance from other students, particularly the three main protagonists Akari, Yuki, and Nozomi, who form the unit R3. Unlike the three girls who grow close and work together as a group, Jun rejects collaboration, deciding instead to pursue her career as a solo artist. Her primary role within the story is that of a rival to the main trio, providing a contrasting perspective on what it takes to succeed in the idol industry. While other students who were not selected for Class S become jealous of the chosen members, Jun remains focused on her individual path and the competitive nature of the music business. The narrative explores her relationship to the main characters as a competing student, and her development involves her stance against forming a unit with them. No information is available regarding Jun's personal background, family, specific motivations beyond her competitive philosophy, her character development over the course of the series, or any notable musical abilities or singing style unique to her.