"Gekijō-ban Aikatsu Planet!" is a theatrical anime film that expands on the "Aikatsu Planet!" multimedia franchise, which revolves around the world of idol performances and competitions. The story centers on Mahiru Kasumi, a cheerful and determined girl who aspires to become a top idol. She discovers the existence of Aikatsu Planet, a virtual world where idols compete using holographic avatars called "Dressia." These avatars allow performers to showcase their talents in dazzling, otherworldly stages.

Mahiru joins the Aikatsu Planet Academy, a prestigious institution where aspiring idols train to perfect their skills. Alongside her friends, including the talented and supportive Kokone Nijiiro, Mahiru navigates the challenges of idol life, balancing rigorous training, creative performances, and personal growth. The narrative explores themes of friendship, perseverance, and self-discovery as Mahiru strives to achieve her dreams.

The plot intensifies when a mysterious rival, Rei Kizaki, emerges, challenging Mahiru and her friends with her exceptional talent and enigmatic personality. Rei's presence adds a layer of competition and intrigue, pushing Mahiru to refine her abilities and confront her insecurities. The story also delves into the dynamics of teamwork, as Mahiru and her peers collaborate to create unforgettable performances that captivate audiences.

As the narrative progresses, Mahiru faces pivotal moments that test her resolve, including high-stakes idol battles and personal dilemmas. The film culminates in a grand event where Mahiru and her friends showcase their growth, delivering a performance that embodies their dedication and passion for idol culture. The conclusion highlights the transformative journey of the characters, emphasizing the importance of hard work, camaraderie, and staying true to oneself.

The main characters include Mahiru Kasumi, the optimistic protagonist; Kokone Nijiiro, her supportive and talented friend; and Rei Kizaki, the skilled and mysterious rival. Each character contributes to the narrative's exploration of ambition, rivalry, and the pursuit of excellence in the competitive world of idols. The film maintains a balance between lighthearted moments and emotional depth, offering a compelling portrayal of the challenges and rewards of idol life.