In 1996, following the defeat of SpaceGodzilla, Miki Saegusa of the United Nations Godzilla Countermeasures Center (UNGCC) travels to Birth Island to monitor Godzilla and Little Godzilla, only to find the entire island destroyed and both monsters missing. Godzilla, now covered in lava-like rashes, subsequently appears in Hong Kong and destroys great swathes of the city with an empowered version of his atomic breath. The JSDF hires college student Kenkichi Yamane to unravel the mystery of Godzilla's condition. Yamane, a grandson of the same Dr. Kyohei Yamane who had encountered the first Godzilla, suspects that Godzilla's heart, which acts as a nuclear reactor, is undergoing a nuclear meltdown as a result of the monster absorbing the energy released from a volcanically triggered uranium deposit on Birth Island. Yamane theorizes that when Godzilla's temperature reaches 1,200 °C, he will explode with enough energy to ignite Earth's atmosphere and reduce the planet's surface to ash.