A small group of young girls possessing strange abilities, along with a tree that has grown through a railcar, cling to life in a desolate land while searching for its last remaining water reservoirs. Their routine struggle for survival is interrupted by the arrival of Wakaba, a boy who has no memory beyond his own name. The girls and their new companion embark on a perilous journey across seas of burning red fog, aiming to find what they need to sustain themselves on the more distant, dangerous islands swarming with robotic bugs. Their ultimate fate will be determined by their own strength, as well as Wakaba's curious ability to understand the Kemurikusa: mysterious glowing leaves with wondrous powers. Alongside the girls, Wakaba, and the hordes of ravenous bugs, the Kemurikusa are the last sparks of life surviving in this land. How did things end up this way? Why are there so many empty buildings with no one to live in them? Wakaba and the girls lack the answers to these questions, which means the truth can only be found within the Kemurikusa.