Kaori Ayase (綾瀬 かおり Ayase Kaori) is one of the supporting female characters in both the anime and manga. She is Mizuki Usami's best friend who are students in the same class.
Kaori is a young 14 years old middle school girl with shoulder-length blonde hair, orange eyes and a red ribbon on top.
Kaori is a very cheerful girl who would do anything in order to get Mizuki Usami and Subaru Uchimaki together. She often teases Mizuki about her crush on Uchimaki. She loved her yo-yo and was a bit upset when it got ruined.
Mizuki is Kaori's best friend. They are students in the same class. She and Mizuki are also childhood friends. Mizuki would often call her "Kaorin" and Koari would call Mizuki "Mizu" or "Mizu-chan". They're relationship together could be compared as of which of Aoi and Yurine.
Kaori seemed to dislike Imari at first by the fact that, according to her, she was "About to take Uchimaki-Kun away from Mizu", so one day she decided to spy on her as an attempt to expose her so Uchimaki "stays" with Usami. This results on Kaori following Imari around the streets until she tripped, which ended up on Imari noticing her and asking if she was okay.
After being bandaged by her, Kaori sat down silently while Imari talked to her, as she recognized her as Usami's friend. She then proceeded to talk about Usami, pointing out that she was cute; that she was a bit clumsy, but that she's cheerful, kind, and cares about her friends, which was why she loved her. After Kaori got hungry, she got a Ramen Snack from Imari (Despite still not talking to her); then it started to rain, to which Imari decided to share her umbrella with her and walk to her home.
- Kaori's surname Ayase means "design" (綾) (aya) and "swift current, rapids" (瀬) (se).