A large nuclear power plant near Mount Fuji has begun to melt down; its six reactors explode one by one. The breaches fill the sky with hellish red fumes and send millions of Japanese citizens fleeing in terror towards the ocean. After an unspecified amount of time, two men, a woman, and her two small children are seen alone, left behind on land in broad daylight. Behind them is the sea. The older man (Hisashi Igawa, who appeared in a number of Kurosawa's later movies), who is dressed in a business suit, explains to the younger man that the rest have drowned themselves in the ocean. He then says that the several colours of the clouds billowing across the now rubbish-strewn, post-apocalyptic landscape signify different radioactive isotopes; according to him, red signifies plutonium-239, a tenth of a microgram of which is enough to cause cancer. He elaborates on how other released isotopes cause leukemia (strontium-90) and birth defects (cesium-137) before wondering at the foolish futility of colour-coding radioactive gases of such lethality.