Let's go together - meet the beautiful scenery with irreplaceable friends. Aoi, who loves indoor activities and is afraid of heights, reunites with her childhood friend Hinata when she enters high school. Although she is exhausted under Hinata's leadership, she has accumulated experience in mountaineering and outdoor activities. Aoi gradually enjoys mountaineering. After that, their season changes from summer to autumn. Aoi and her friends who have increased as a result of mountaineering try to think about which mountain to climb next. Hinata gradually feels relieved as she watches Aoi train her physical strength with the goal of climbing Mount Fuji and actively challenge new outdoor activities... Laughing, crying, climbing... "Heading to the Mountain" depicts middle school mountaineering girls who enjoy the joy of climbing. The long-awaited "Third Season" is finally open!