(Years after Godzilla and the other Earth monsters' victory against King Ghidorah and the Kilaaks, the planet has returned to peace. Until an unknown alien race invaded the planet, but not with the help of a mind controlled monster, or an artificial one... Instead they created a virus. Contained within large capsules, once someone comes into contact with it, the capsule will release the virus into the the air. The infected will immediately show signs of being affected by the virus, and within as short as 5 minutes they will mutate into horrific and hostile monsters. This even infected the kaijus, causing the entire world to fall, and fall it did. Human civilization has fallen to the infected, and the aliens are already winning...)

Humanity and the few remaining uninfected kaijus remain within a highly barricaded version of Tokyo. Now dubbed "Kowarenai Tokyo", the few smartest minds continue to and find a cure to all of this. However, as of now no cure has been made...