A girl who appears friendly and sweet to everyone around her, she has had a huge crush on Kazehaya since their first year of middle school. She dislikes her given name, Ume, because it sounds old-fashioned and prefers to be called her nickname, “Kurumi.”
She is extremely jealous of Sawako, which led her to spread fake rumors of Sawako’s only friends at the time, Yoshida and Yano, using Sawako’s name. Kurumi does not attend the same class as Sawako or Kazehaya. She eventually confesses her love to Kazehaya, but receives an expected rejection. Because she is always surprised with Sawako’s naiveté, Kurumi is able to become friends with her, as well as a rival for Kazehaya’s affection. Following Kazehaya’s rejection, she becomes colder to her classmates, but is able to finally express her true feelings and personality.