Rin is the main heroine in the story. She is the younger sister of Kyousuke Natsume and is the only female member out of the five original members of the Little Busters. She does not communicate well and is seen as inarticulate. Due to this, she is anti-social, and is usually seen alone. When playing baseball with the others, Rin is an ace pitcher, although she used to be quite a bad pitcher — her throws would go in completely unpredictable directions — until she gets into a baseball stand-off between Sasami, where she demonstrates two "super-power" pitches, where one of them is a fastball and the other one is her own version of a changeup. Rin loves cats and at school takes care of several strays; it is not uncommon for several cats to crawl onto her.