Akuru's little sister who is in the fifth grade. Ruri is a hardworking elementary school student who devotes her time to studying and she is determined to become smart and dependable. Despite this, she utterly fails at nearly everything she does, which prompts Yoshiko Hanabatake to see her as a fellow "idiot". Much like Akuru Akutsu (Ruri's older brother), Ruri dislikes Yoshiko and she is mortified at the idea of becoming just like her. Unlike Yoshiko, Ruri has a good amount of common sense, though sometimes her childishness will come out at points.