Eiji, a boy who lives in Aiga, a world whose inhabitants hate the “sky.” When he catches a girl named Patema who has fallen down from an inverted, underground world, the two of them fly off into the sky. Beginning with this encounter between two people living in worlds with inverted skies, the story is a spectacular journey full of surprises in search of the mystery of the “reversed world”. This challenging work pursues the vivid expression of gravity through the feeling of floating and falling.