The story is set in Japan a millennium from now. Five children the protagonist Saki, Satoru, Maria, Mamoru, and Shun have been born and raised in a tranquil town that can be described as a utopia, overflowing with water and green foilage. After a certain incident, Saki and the others come to realize the true nature of their world. The five throw themselves into life-threatening adventure and fighting to protect friends and a world on the brink of collapse.
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