In the vast expanses of the sea, the war between pirates and imperial authorities does not stop. The legend of the seas, Rapis, captain of the Sea Serpent, nicknamed the Fearless Demon, dies, leaving command of the ship to his daughter Ridarete and entrusting the pilot Raladan with her care. Ridareta will give birth to children, two twin daughters, and their birth is colored by a series of crimes. Are they people or demons, these strange creatures born under the cover of secrecy? Why is nothing in the world able to kill them, and even a cut throat heals almost instantly, leaving only a disappearing scar? Why are their hearts so cruel and devoid of pity that it seems they have no hearts at all? For what purpose do the sisters rebel? Pilot Raladan sets off on a journey to the homeland of magic, to the mysterious Bad Land, to find answers to all these burning questions on which the fate of the empire and the people inhabiting it depends.