Kokona Aoba is a 13-year-old middle school student with ochre hair and red eyes, standing 1.44 meters tall. Her gentle and observant nature fuels a strong passion for wildlife, particularly flying squirrels, motivating her outdoor explorations. Aoi Yukimura and Hinata Kuraue first encounter her during their mountain-climbing activities when she is climbing Mount Takao alone to observe flying squirrels. After assisting her, they discover they share the same city, leading to regular joint hikes and a deepening friendship centered on their shared love for the outdoors.

Kokona's enthusiasm for wildlife observation frequently drives the group's adventures, as she actively seeks opportunities to encounter animals like fireflies during their excursions. Background reveals a forgotten chapter: Kokona crossed paths with Aoi and Hinata as children when they were lost in a forest. Dressed in a firefly costume, she helped them find their way, a meeting neither recalled in their later interactions.

Her family includes her mother, Mai Aoba. Kokona receives hiking shoes as a birthday gift, which she diligently tests during walks around town to familiarize herself with the new equipment. She integrates into the group through recurring hikes and activities, such as visiting the Hanno River with Aoi, Hinata, and Kaede. Her presence contributes to the dynamic of collective mountain exploration, including participation in the group's ascent of Mount Fuji alongside Aoi, Hinata, Kaede, and Honoka.