From the introduction:
Japan, 2130 AD, shortly after the third World War. Gigantic contaminated regions have erupted all around the country, called “Black Spots”. Black Spots are treated as ruins, and are quarantined by a huge wall. Regardless, there were those that would make that ruined land their home. They were, at first, ignored, but certain individuals emerged with strange powers.
Fire, Wind, Gravity... They could control the very forces of nature. In fearful ignorance, people called them “Needless”.