In a world destroyed by apocalypse, Wadatsumi resides in a watery domain, where the land is ruled by water. With unwavering conviction, he deems his home to be the solitary remaining piece of land on earth. Nevertheless, his life takes an unforeseen course when a mysterious girl, carried to him by the fierce tides of the sea, appears before him. This unexpected encounter triggers Wadatsumi's contemplation about the girl's origins and the possibility of other land masses.