The Gastrea virus spreads rapidly, causing infected hosts to mutate and gain new abilities while continuing to harm others. The human race is unable to fend off this enemy that turns defenders into foes. Their only defense is to retreat into fortified cities made of Varanium, a scarce material that can halt the virus. The last hope for humanity rests on the Cursed Children; young girls who, despite their infection, have maintained their humanity. They are teamed up with a partner and have the capacity to defeat Gastrea in one-on-one combat. However, their power comes at a cost as they are feared and outcast. The question remains whether they are saviors, monsters or simply girls.