Coppelion

Coppelion (コッペリオン) is a Japanese seinen manga series written and illustrated by Tomonori Inoue. The story follows three high school girls who were genetically engineered to be impervious to radioactivity and sent to Tokyo after the city was contaminated by a nuclear accident.

Plot
In 2016 a meltdown of a nuclear power plant creates a big catastrophe in Tokyo. 20 years later, the city has become a ghost town due to the high levels of radiation. From that area a distress signal is received, the Self-Defense Forces dispatch 3 girls from the special unit Coppelion to search for survivors. But why aren't they wearing any protection against radiation?

Official

 * http://kc.kodansha.co.jp/