Miru Nagisa is a fifteen-year-old girl and one of the new members of the reborn musical group the Lemon Angels. She has long, flowing black hair and red eyes, and her style of dress is reminiscent of Gothic Lolita fashion. She is extremely soft-spoken and rarely speaks or sings unless she feels it is absolutely necessary. Her quiet and reserved demeanor masks a difficult past: she lost both of her parents in a fire at a young age, an event that caused her to withdraw from the world and become a hikikomori, isolating herself at home. Her deep connection to music began when she discovered the songs of the original Lemon Angels, particularly the lead singer Anne. Their music moved her so profoundly that it drew her out of her isolation, and she became determined to follow in Anne's footsteps and become a singer herself.

This admiration for Anne is the foundation of Miru's motivation. She joins the new Lemon Angel Project with the strong desire to become the group's lead singer, mirroring the role that Anne had in the previous incarnation of the group. However, as she gets to know her fellow members, she recognizes that Tomo Minaguchi, the eventual lead singer of the new group, possesses a spirit and quality similar to Anne's. Realizing that Tomo is more suited to be the center of the group, Miru steps back from her own ambition, choosing to support Tomo rather than pursue the lead role for herself. This decision reflects a key aspect of her character: a tendency to put the needs and talents of others ahead of her own desires.

Within the group, Miru is dedicated and works hard to contribute to the Lemon Angels' success. Her soft-spoken nature means she is not an assertive presence, but her determination to overcome her past and her commitment to the project are unwavering. Throughout the series, she gradually emerges from her shell, growing more confident as an artist and as a person. While she begins as a shy girl who can barely bring herself to sing, she evolves into a capable and reliable member of the idol group, embodying the perseverance and inner strength needed to pursue her dream. Her primary abilities lie in her quiet but steady singing voice and her growth as a performer, and she also has a practical skill in sewing, which she uses to create costumes for the group.