2250, human technology reaches an unprecedented height, each country has its own technological development route. Country A carries out project on Human Genetic Alteration and there are plenty of volunteers is tested on an uninhabited island.
Yet a major mistake is occurred in the laboratory and huge explosion produces vast amount of toxic chemicals spread globally through atmosphere and sea which turns all man kind into KSEKAI.
A few years after, folders are found in the laboratory of ruins in uninhabited island. However, the documents for developing antidote for the outbreak is unable to be decrypted as people involved are disappeared in an accident.
Thereby they start recruiting a total of KSEKAI 6000 persons in total. For the purpose of decrypting the research files, developing antidote and save affected humans.