She is Yukimura's younger sister. Her first appearance in the anime is episode 20. Once she sees Usui she immediately calls him her "ouji-sama" (prince). After a date in which Misaki devises several 'methods' in order to get Yukimura to look more prince-like, Ruri decides that Takumi-sama's 'princess' is not her. At first, Ruri disliked telling people that Yukimura was her brother (which made Yukimura very upset), but she eventually sees the 'prince' in him and she and Yukimura get on good terms again.