Aoi Yukimura lives in Hannō and initially retreats indoors, her introversion compounded by acrophobia stemming from a childhood fall on playground equipment that broke her leg. This accident fundamentally altered her relationship with heights and outdoor activities, leading to social isolation early in high school. Her background includes formative mountaineering experiences with her father and childhood friend Hinata Kuraue before the incident, particularly a sunrise viewed from a mountain summit—a memory that later anchors her emotionally.

Reuniting with Hinata at high school's start sparks her renewed engagement with mountain climbing. Despite persistent fear, she gradually resumes hiking at Hinata's encouragement, beginning with accessible peaks like Mt. Tenran where she learns initial trails often follow manageable visitor paths. Early outings involve basic outdoor skills such as tent pitching under Hinata's father's guidance and participating in camping cooking contests that reveal her culinary aptitude.

Her development spans practical mountaineering skills and social confidence. While browsing outdoor equipment stores, she meets experienced climber Kaede Saitō, assisting her with gear selection like sleeping bags ("schlafsacks") and backpacks. This mentorship evolves into friendship, expanding her social circle. Subsequent climbs, like Mt. Takao, demonstrate her growing enthusiasm—though initial overexcitement causes fatigue—and sense of responsibility when purchasing souvenirs for companions. On this hike, she encounters and aids Kokona Aoba, mending her broken shoe and integrating her into the group, showcasing emerging leadership.

Confronting figurative and literal mountains defines her journey. She incrementally challenges her acrophobia through progressively difficult hikes, aided by gear acquisition and technique refinement. Selecting a backpack with proper hip-belt fit for load distribution improves her endurance and trail comfort. Later, summiting Mt. Fuji brings altitude sickness, but she perseveres with group support. These experiences foster resilience, shifting her mindset from viewing setbacks as failures to valuing perseverance and adaptability, finding joy in hikes despite poor weather or obstacles.

Her social growth extends beyond the core group. She initiates connections, inviting Kokona for sleepovers and collaboratively preparing trip meals. She later facilitates bonds between newer members like Honoka Kurosaki and Kokona, recognizing their shared interests and age proximity during hikes to locations like Mount Mitake. Working part-time at a cake shop alongside college student Hikari Onozuka further broadens her interpersonal experiences. Later, she assumes mentorship roles within the mountaineering club, assisting peers like Koharu Senjuin during activities such as snowshoeing on Mount Akagi, demonstrating leadership through emphasis on preparation and safety.

Her trajectory reflects continuous, nonlinear growth across all seasons and OVAs. She transitions from reluctance and fear to proactively planning expeditions and mentoring others. Flashbacks to her childhood accident and the pivotal sunrise moment with Hinata inform her motivations, while ongoing challenges—like indoor climbing in OVAs—reinforce her commitment to overcoming limitations. Relationships evolve from dependence on Hinata's initiative to mutual support and independently expanding her circle, embodying a journey from isolation to community integration through shared outdoor experiences.