Coppelion (2013)

Set 20 years after a nuclear meltdown devastates Tokyo, the city is now a ghost town with high levels of radiation preventing humans from inhabiting it. However, a distress signal is received from within the city and the Self Defense Force dispatches three girls to search for survivors. Their unit is called Coppelion, but in a city where radiation suits cannot keep humans protected for long, why are they wearing nothing but school uniforms?