Kaoru Hanawa is a childhood friend of Fū Sawatari, having played together during Fū's earlier time in Takehara. She was the first to speak to Fū when she transferred to their school and helped her overcome her initial shyness. Kaoru has reddish-brown hair typically worn in a ponytail.

She proclaims a strong interest in all sorts of smells, often described as a 'smell fetish,' and enjoys creating various blends of potpourri. Despite this interest, she has not chosen a career path related to it. In her group of friends, Kaoru often acts as the tsukkomi, reacting to the antics of others, particularly Norie's energetic behavior.

Kaoru has an older sister named Sayomi Hanawa, who enjoys exploring small, undiscovered places and frequently takes Kaoru and her friends on lengthy trips. A running gag involves Kaoru's repeated but unsuccessful requests for Norie to stop calling her by the nickname "Kao-tan."

She is part of a core friend group that includes Fū Sawatari, Maon Sakurada, and Norie Okazaki. Together, they experience everyday life in Takehara, often participating in local activities, visiting cafes, and sharing meals. Kaoru is considered one of the few who understands Fū beyond her perceived quirks.

In the group's dynamic, which is sometimes associated with the five senses, Kaoru represents the sense of smell. Her character remains consistent and supportive, providing a stable presence for her friends.