In the year 3567, humanity struggles to survive amidst the ruins of a lost civilization, constantly threatened by enigmatic Gardeners—autonomous Moon-originated weapons. To make ends meet, courageous teenagers must take on the perilous role of hunting down these Gardeners. Despite the widespread collapse of advanced technologies that once sustained human society, scattered remnants of functioning city sectors still provide some support to the surviving population. When Tokito Aizawa crosses paths with Tea, a mysterious encounter reveals a power far older and more potent than that possessed by the Gardeners, setting the stage for a potentially brighter future for the remnants of humanity.