As the Seishou Festival approaches, the 99th class of Seishou Music Academy is immersed in preparations for their performance of Starlight, a poignant story about two deities linked by a celestial light who are fated to remain apart forever. This single-gender school, dedicated to cultivating future theater talents, focuses on training in singing, acting, and dance. Sixteen-year-old Karen Aijou, an easygoing student with a lifelong passion for performing, rediscovers her enthusiasm when her childhood friend Hikari Kagura transfers back to the school. With Hikari's assistance, Karen discovers a hidden elevator that leads to a vast underground theater, run by a talking giraffe. There, students engage in fierce competitions to win the prestigious title of Top Star, which guarantees a lead role in Starlight. Driven by a promise to achieve stardom together, Karen joins these mysterious contests to fulfill their shared dream.