Anime following the adventures of a group of cryogenically frozen survivors of a virus that decimates the population of Earth. When a virus called Medusa breaks out in Japan and spreads with frightening speed, turning its victims to stone, those in power desperately search for a cure. As part of the experiments, a group of patients are frozen with a view to awakening them when the worst of the virus has passed. However, when Kasumi (voice of Kana Hanazawa) awakes the crisis is far from over. Indeed, it seems to have entered a horrifying new stage. Will she find a way to survive?