Mari Maya is an eighteen-year-old idol who serves as the center of the three-member idol group Mineral Miracle Muse. In addition to performing, she composes the group's music and writes their lyrics. She presents a bright, cheerful, and outgoing personality, easily approaching others and acting as a mood maker. Beneath this exterior, she is headstrong, confident, and stubborn, with a tendency to become moody when things do not go her way. Her motivations for becoming a vigilante stem from a desire for thrill and a direct, physical means of punishing criminals, which contrasts sharply with the more idealistic, no-harm philosophy of the protagonist. After rescuing him from a group of carjackers who were about to expose his secret identity, she blackmails Masayoshi Hazama into partnering with her. Operating under the alias Flamenco Girl, she uses a custom-made staff equipped with pepper spray, spikes, and a stun gun, employing brutal and unorthodox methods that often draw police complaints. When Masayoshi ends their partnership, she reforms as Flamenco Diamond and recruits her two fellow group members, Mizuki Misawa and Moe Morita, to form the Flamenco Girls, a trio of vigilante idols. Her key relationships include a competitive and often antagonistic dynamic with Masayoshi, a dynamic mediated by the police officer Hidenori Gotou, for whom she develops a romantic and physical interest, particularly drawn to him in his police uniform. She shares a close, loyal bond with her groupmates, with Mizuki acting as a voice of reason and Moe as an unwavering supporter. Her character undergoes significant development when she is kidnapped and tortured by the villain King Torture. This trauma causes her to become distant, angry, and bitter, developing a hatred for superheroes and living in hiding at Gotou's apartment out of shame and feelings of inferiority, particularly toward Moe. She eventually reconciles with her friends, explains that her withdrawal was driven by those feelings, and resumes her role as Flamenco Diamond. Her notable abilities include her talent as a songwriter and composer, her skill with her custom fighting staff, and her willingness to use extreme measures in combat.