Having already tackled Mt. Mitsutouge, which offered a fantastic view of Mt. Fuji, Aoi wants to make another attempt at reaching the summit of Fuji itself. Unfortunately there’s no opportunity to do so until the next summer vacation, so in the meantime she and her friends visit an assortment of other mountains while continuing to enjoy their everyday school life.
This continues from where the second season left off with a similar variety of content. While it can be watched without having seen the prequel, you’re expected to already be aware of the characters’ histories and relationships.
More Information:
aniDB
Crunchyroll
Wikipedia