Kaoru Hanawa is Fu Sawatari's childhood friend, having played together during Fu's earlier time in Takehara before Fu's family moved away. She warmly welcomes Fu back upon her return five years later, actively helping the initially shy Fu adjust to her new school and make new friends. Kaoru frequently watches over Fu, especially when Fu becomes engrossed in photography and loses awareness. She possesses a perceptive understanding of Fu's emotions and occasionally teases her affectionately.

Kaoru sports reddish-brown hair typically styled in a ponytail and has brown eyes. Her most distinctive trait is her self-professed fascination with scents, often described as a 'smell fetish'. This interest manifests in her hobby of creating various potpourri blends. She exhibits this fascination through actions like enjoying the smell of Fu's hair. She engages in everyday activities with Fu and their friends, Maon Sakurada and Norie Okazaki, including participating in the Photography Club and joining adventures orchestrated by her older sister.

Her family includes her older sister, Sayomi Hanawa, known for organizing spontaneous, often lengthy exploratory trips. Sayomi coined Fu's enduring nickname, "Potte", which Kaoru regularly uses. Kaoru sometimes participates in Sayomi's Mini-Sanctuary Explorers Club activities.

Throughout Fu's high school years, Kaoru remains a steadfast emotional anchor, particularly as Fu grapples with her future and her passion for photography. While Kaoru initially feels uncertainty about her own career direction compared to her friends' clearer aspirations—Fu's photography, Norie's patisserie goals, and Maon's artistic pursuits—she demonstrates strong organizational skills. This talent is prominently showcased when she conceives and single-handedly coordinates the "We Exhibition". This event highlights her friends' talents and hobbies, requiring significant planning for venue acquisition, layout design, and scheduling, subtly pointing towards her potential future in event coordination or project management. As graduation approaches, she thoughtfully contemplates her own future while steadfastly supporting Fu's decisions, reflecting her growth and reliability.