Kokona Aoba is a petite 13-year-old girl, standing 144 cm tall and weighing 38 kg, with a birthday on August 11. Her long, wavy brown hair features a braided section in her bangs, enhancing her "forest girl" look. She lives with her mother, Mai Aoba, who works in the clothing industry, while her father travels frequently for business, leading to long absences. This family situation fostered Kokona's early independence, making her skilled at household chores and cooking. Financial constraints also taught her to value small pleasures and spend money carefully.

She first met Aoi Yukimura and Hinata Kuraue on Mount Takao's slopes when her shoe sole partially detached during an attempt to observe dwarf flying squirrels. Aoi's emergency repair sparked their friendship, later expanding to include Kaede Saitou, forming a close group bonded by outdoor interests. An earlier, forgotten encounter occurred in childhood when Kokona, dressed in a firefly costume, helped a lost Aoi and Hinata find their way in a forest; this incident incidentally caused Hinata's fear of fireflies.

Kokona displays a gentle, cheerful, and supportive personality. Despite her delicate frame, she possesses notable physical strength and endurance, enabling her to tackle challenging climbs like Mount Fuji. She is resourceful and quick-thinking, often sharing trivia about nature and animals that impresses her friends. Her interests include a strong affinity for cute animals, especially horses and flying squirrels, and she collects horse-themed mascots like Yumema-kun and Gunma-chan. She enjoys exploring nature on foot and daydreaming.

Her development shows increased confidence in mountaineering and social interactions. She actively participates in group hikes, demonstrating resilience by completing physically demanding ascents. She also begins considering future education, aiming to attend the same high school as Aoi and Hinata due to its proximity, appealing uniforms, and scholarship opportunities, for which her academic performance qualifies her.