Nuclear war has begun. Warheads soar through the sky across the globe, mushroom clouds erupt and cover continents, radiation infects and poisons the environment.

Before your area gets nuked, a girl calls you into a nearby bunker that she has. With no other option, you accept her invitation. You successfully survive the nukes, but now you must live in a large bunker with this girl until the radiation disappeared from the environment to a safe level...