After a virus broke out, zombies appeared and quickly took over the world. In a short amount of time, most of the population had succumbed.
However, some were still alive, doing their best to keep on living. But, no matter where you went, even if you managed to find survivors, they were all going to be male. Mikazuki Shizuka was special, an exception. In a sense, she was the last woman on Earth.
