Ai Minamizato is a high school student whose physical appearance includes brown hair and red eyes. She stands 1.53 meters tall, and her birthday is on December 1. There is conflicting information regarding her blood type, with some sources listing it as type O and others as type A. Her personality is defined by a pronounced shyness, particularly around male individuals, which often makes it very difficult for her to speak to them without considerable effort and encouragement. In social situations involving boys, her knees may tremble, and she generally relies on the support of her close friend, Miyuki Iijima, who provides encouragement and sometimes directly intervenes on her behalf. This inexperience and anxiety in interactions with the opposite sex is a recurring aspect of her character.

Within the story, Ai Minamizato has two distinct primary roles depending on the adaptation. In the original OVA production, she is an underclassmate at the same school as the main characters and develops romantic feelings for an upperclassman named Tohru Nagase. Her affection for Tohru introduces an external complication to the central romantic dynamic involving Tohru, Mizuho Yuuki, and Miko Kamiyama. In the television series adaptation, her role is similar in essence but directed toward a different character, Tsuyoshi. In this version, she is introduced in a scenario where she is attempting to rescue a kitten stranded in a tree, an act through which she first comes to Tsuyoshi's attention. It is also mentioned that in the television series, she has secretly held romantic feelings for Tsuyoshi for a considerable time before this encounter.

The key relationship in her life is with her best friend, Miyuki Iijima. The two have been friends since their first year of high school, and their personalities are complete opposites, as Miyuki is much more outgoing. Ai depends heavily on Miyuki for support in navigating social situations, especially those involving potential romantic interests. Her motivations are largely driven by her hidden romantic affections and her desire to connect with the object of her feelings, despite her overwhelming shyness and fear of men, known as androphobia. Her character development primarily involves the slow process of overcoming this fear and finding the courage to confess her feelings, a significant step given her extreme introversion. Her general inexperience extends to other areas, as she has very few motor skills and does not participate in any club activities, so she is typically seen either at school or at home.