Godzilla is the last of a group of prehistoric creatures that lived during a time when radioactivity levels on land were high. When those radioactivity levels depleted, he went too the deep ocean, and returned when humans started using nuclear energy. In 1954, Godzilla attacked Tokyo, leaving it in temporary ruin. Then, the USA military thought they had destroyed him after nuking him, but he returned to aid humanity when the MUTOs were about. Ever since, Godzilla was everyone's hero. This story takes place a few years after the fight in San Fransisco.