Yui is a cheerful, outgoing girl who becomes the Service Club's first "customer", asking them to help her bake cookies for "a certain someone". Her problems lie not with her personality, but with her inability to deal with issues by herself. She believes that talent is inborn, and often aspired to be like others until Yukino changed her way of thinking. Following her experience with the Service Club, Yui begins to attend Service Club sessions after school as well, despite Yukino's objections early on.

She is the owner of the dog that led to Hachiman's accident.

She has feelings for Hachiman which she admits to the members of the Service Club in the final episode of the series.