The year 13,800 A.D. Due to an apocalypse that ravaged the entire earth several centuries earlier, humans have been relegated to the position of an endangered species on blighted land. Only a small sliver of green is left, the acidic oceans are aflame and the blue skies remain no more. The earth cannot even produce sustenance for people to survive. Sui was raised the daughter of a florist in City Gilde, but on her 18th birthday things suddenly shift and her peaceful, if poor, life is thrown into turmoil. A sudden coup d'etat occurs and fatally injured in the fray, her surrogate mother, Nene, relays to her a shocking message with her dying words - Sui is actually the last surviving member of the royal family and a princess heir to the throne. So Sui sets out on a journey with Laliela to take the Key of Will bequeathed to her by Nene to the Sage U.