A few young girls with remarkable abilities and a tree that has grown through a railway cling to life in a bleak region in quest of its final water reservoirs. Their daily fight for survival is disrupted by the arrival of Wakaba, a youngster with no recollection other than his own name. The girls and their new friend go on a treacherous trek over oceans of flaming red fog in search of what they need to survive on the more remote, deadly islands teeming with robotic bugs. Their final fate will be determined by their own strength, as well as Wakaba's remarkable ability to comprehend the Kemurikusa: enigmatic luminous leaves endowed with astounding abilities. Aside from the females, Wakaba, and swarms of voracious bugs, the Kemurikusa are the last sparks of life surviving in this land. How did things end up this way?