Mariko is an underground idol who performs at a live house in Shibuya called DESEO. She loves music and genuinely enjoys performing, but she lacks the funds and connections needed to reach a wider audience. Her style and stage presence are well received in the small venue, and for a time she was content with these modest gigs. However, spurred on by her passionate fan Ryu-san and the encouragement of others, she becomes determined to aim for a major debut and achieve stardom. She is extremely talented, yet she struggles to gain the same level of popularity as the local idol group Itorio, which creates a central tension in her journey. Her motivations are driven by a deep love for music and a desire to be recognized beyond her underground scene. Throughout the story, Mariko evolves from a performer satisfied with her niche audience into an idol willing to take risks and push herself to reach a larger stage. Her key relationship is with Ryu-san, a devoted otaku who becomes her primary supporter and helps drive her ambition. She also exists in indirect rivalry with Itorio, whose rising success highlights her own challenges. Her notable ability is her raw talent as a rock-influenced singer, which draws in a dedicated fanbase despite her limited resources.