Ai Shindō is a cat youmu residing with her older sister Ayaka Shindō at a photo studio. She pitches in with household chores and models for photographs as part of her routine. Physically, she presents as a petite adolescent girl possessing wavy brown hair reaching mid-back, short fringes, and large blue eyes. Her round, innocent facial features are matched by a soft, melodious voice. Experiencing strong emotions triggers her reversion to her true youmu form, manifesting as a Scottish Fold cat with distinctive white-tipped tails.

Her personality radiates cheerfulness and excitability, frequently leading to emotional outbursts that cause transformation. She exhibits inherent warmth and gentleness, consistently supporting those around her and striving to maintain peace. Academically, she attends Nagatsuki City High School as a second-year student, forming friendships with classmates Sakura Inami and Mirai Kuriyama.

During the school's Fruit Type youmu incident, she initiates an idol band with Mirai, Akihito Kanbara, and the Nase siblings to distract the creature. Taking the lead performer role, she demonstrates proficient singing abilities. The plan falters when the youmu releases a defensive scent, forcing repeated showers. Later, during the Calm phenomenon inducing youmu lethargy, she nearly falls victim to Akihito's hostile youmu side until Ayaka intervenes. Subsequently, both sisters are absorbed by the massive youmu "Beyond the Boundary," joining Akihito and Mirai to battle hostile entities within.

In the movie "I'll Be Here - Mirai-hen," she enthusiastically joins tennis club tryouts with Mirai and Sakura, displaying natural athletic aptitude despite no prior experience. Later, she overhears a serious conversation between Ayaka and Hiroomi Nase regarding the Nase family's future. She chases after Hiroomi to apologize, expressing that Ayaka holds "high expectations" for him and affirming their happiness coexisting with humans.

Beyond the main series, she stars in the original net animation "Idol Trial" as a presiding "idol judge" evaluating other characters' behavior. In this role, she adopts a super-deformed appearance, wearing frilly idol attire beneath judicial robes while masking a sharp-tongued demeanor with cute mannerisms. Additionally, in the "Mini Theater" specials, she voices aspirations for an idol debut, reinforcing her interest in performing.

Her surname "Shindō" combines the characters for "new" (新) and "temple" (堂), while her given name "Ai" (愛) means "love" or "affection".