Cecil Aijima was born a prince in the fictional desert kingdom of Agnapolis (Agna Palace), the son of an Arabian king and his Japanese mother, Aijima Kotomi. His mixed heritage made him a target for persecution by relatives, including his uncle and cousins, who deemed him unworthy of royalty. They cursed him to live as a black cat and exiled him to Japan. In Japan, he encountered Haruka Nanami. Her kindness in caring for him and naming him "Kuppuru," combined with the power of her music—linked to her being a reincarnation of the goddess Muse, whom Cecil's family served—broke his curse, restoring his human form and igniting his profound devotion to her.

Initially confident and occasionally blunt, Cecil openly expressed his admiration for Haruka and dismissed becoming an idol. His early days at Saotome Academy revealed cultural misunderstandings stemming from Agnapolis' desert environment, including a fear of water and fish, alongside struggles with Japanese language and customs. Though initial friction occurred with STARISH members, particularly Syo Kurusu, Cecil's earnestness and unique perspective gradually integrated him into the group. His relationship with his mentor, Camus, evolved from resistance to mutual respect as Cecil proved his dedication to music and training.

Cecil developed from a self-assured prince into a committed idol, driven by his desire to support Haruka and understand music. He participated in group activities and variety shows, displaying quick wit like impersonating Shining Saotome on television. His insightful nature emerged in interactions with STARISH, offering advice on emotional and professional challenges, such as helping Masato Hijirikawa overcome acting insecurities by channeling personal feelings, showcasing his growth in empathy and teamwork.

In broader media, like the *Maji Love ST☆RISH Tours: Tabi no Hajimari* special, Cecil appears within the STARISH ensemble during their post-"Kingdom" concert activities, contributing to group cohesion and sharing in collective challenges. His familial connection—sharing a mother, Aijima Kotomi, with Otoya Ittoki—is subtly explored, though neither is fully aware of their half-brother relationship in most adaptations.

Ongoing conflicts with his Agnapolis relatives, who orchestrated his curse and later attempted political marriages to control him, form part of Cecil's background. His destiny involves choosing between his throne and his idol career, often requiring sacrifices concerning Haruka. Despite these pressures, his core traits—loyalty, passion for music, and unwavering love for Haruka—remain constant.