An atmon war little chance of survival, however some managed to survive after the explosion, one of the survivors was Dazai.

Many people get together or others fight alone to survive. There were many arguments between the survivors, they fought over food and water

Dazai is completely alone and wanders through the 'desert' where the city once was. After an hour of hiking he found a ruined supermarket, he hopes there is still food there and finally goes in, where he found you