Adol Christin is on a passenger liner called the Lombardia that is sailing from Xandria to the continent of Eresia. He and Dogi were recruited as a crew for the ship in exchange for their boarding. The ship's captain, Captain Barbaros, tells Adol the story of the cursed Isle of Seiren, where ships have vanished while passing by its perimeters. However, Adol's voyage was interrupted by an enormous sea monster attacking the ship. He and the other passengers were flung overboard as it dragged the ship to the bottom of the sea. Adol later awoke on the coast of the Isle of Seiren's beach. An island with ancient, untamed wilderness, populated by creatures seen nowhere else in the world. He later discovers other people who also washed ashore the island, so to aid their search for other survivors, and to better defend themselves from the primordial beasts that roam the island, Adol and his fellow castaways establish a settlement for themselves called Castaway Village. It was not long before Adol found himself experiencing cryptic dreams about a mysterious young woman with flowing blue hair, whose world Adol had never encountered before.