Journey to where the fog never lifts... Libelle, a city by the sea. Those who venture into its fog are said never to make it back alive-a murderous phenomenon that's another of the Four Major Human Errors that has ravaged the world. But for Menou, it just may be the solution she's looking for. To fulfill her role as Executioner, she needs to find a way to murder Akari, the girl who seems to spring back to life whenever she's killed. Maybe this time, Menou will be successful in carrying out her duty... but a calculated encounter with Manon, the daughter of Count Libelle, shifts all their fates in a direction that even Akari never could have predicted. Just what will become of the Executioner and her seemingly unkillable target...?