After a car accident kills their parents, twins Haruka and Sora Kasugano return to their grandparents' countryside home in Okukozome. Haruka reconnects with childhood friend Nao Yorihime and neighbors Kazuha and Akira Amatsume, while Sora, withdrawn and unwilling to leave the house, clings to her brother as her only anchor. From that shared starting point, the omnibus structure branches into a separate romantic arc for each girl.