"Girlish Number" is a 12-episode anime series that explores the behind-the-scenes world of voice acting in the anime industry, blending comedy, drama, and satire. The story centers on Chitose Karasuma, a young and ambitious voice actress who dreams of achieving fame and success. Despite her confidence and self-assured demeanor, Chitose lacks significant experience and often underestimates the challenges of the industry. Her older brother, Gojou Karasuma, works as a producer and provides a grounded perspective, often clashing with Chitose's idealistic views.

Chitose joins a group of voice actresses to work on a new anime project, "Millennium Princess Aria," which quickly becomes a low-budget production with a weak script. The series delves into the struggles and dynamics among the cast, including the cheerful but inexperienced Yae Kugayama, the seasoned yet underappreciated Koto Katakura, the aloof and perfectionist Momoka Sonou, and the idol-turned-voice-actress Kazuha Shibasaki. Each character brings a unique perspective to the challenges of the industry, from dealing with harsh criticism to navigating the pressures of public perception.

As the production of "Millennium Princess Aria" progresses, the series highlights the disconnect between the creative aspirations of the voice actors and the commercial realities of the anime industry. Chitose's initial arrogance gives way to a more nuanced understanding of her craft, as she confronts the limitations of her abilities and the competitive nature of her profession. The narrative also touches on themes of self-improvement, teamwork, and the often-overlooked efforts of those working behind the scenes.

The series balances its critique of the industry with moments of humor and camaraderie, offering a realistic yet entertaining portrayal of the voice acting world. Through its characters and their interactions, "Girlish Number" provides insight into the complexities of pursuing a career in entertainment, while maintaining a lighthearted tone that keeps the story engaging.