In a near-future Japan, Nanagoo City sits between mountains and the sea, and the teenage girls who live there are each finding their own paths toward adulthood. Four of them, Asagi Asuka, Oribe Kotone, Washioka Itaru and Hiiragi Mako, transform into magical girls known as Nanas. Each commands a different elemental power, and together they battle monsters. This four-episode action fantasy OVA in the mahou shoujo tradition comes from a mediamix project born of a collaboration between Kantoku and Shaft.