"B-Project" is a multimedia franchise that includes an anime series centered around the music industry, idol culture, and the challenges faced by aspiring artists. The narrative revolves around Tsubaki Sumeragi, a young woman who begins working as an A&R (Artists and Repertoire) coordinator at the major entertainment company Gandala Music. Her role involves managing and supporting the careers of the agency's idol groups, particularly the male idol units under the "B-Project" label.

The story primarily focuses on three idol groups: Kitakore (Kitaoji Kokoro, Kaneshiro Ryu, and Kikunosuke Terashima), Thrive (Hayama Amon, Bessho Kazuma, and Moroboshi Goshi), and MooNs (Shimotsuki Shion, Mikado Shiki, and Yukinojo Tsubaki). Each group has its distinct musical style, personality, and dynamics, reflecting the diversity within the idol industry. Tsubaki's journey involves navigating the complexities of her new role, building trust with the idols, and helping them overcome personal and professional obstacles.

Throughout the series, Tsubaki faces challenges such as managing rivalries between groups, addressing individual insecurities among the members, and ensuring the success of their projects. The narrative explores themes of teamwork, perseverance, and the pressures of fame, as the idols strive to balance their personal lives with their demanding careers. The series also delves into the behind-the-scenes aspects of the music industry, including concert preparations, media appearances, and fan interactions.

Key characters include Tsubaki, whose dedication and empathy make her a pivotal figure in the lives of the idols, and the members of Kitakore, Thrive, and MooNs, each of whom brings unique talents and struggles to the story. The interactions between Tsubaki and the idols highlight the importance of communication and mutual support in achieving their goals. The anime blends drama, comedy, and music, offering a glimpse into the world of idol culture while emphasizing the human connections that drive the industry forward.