When the Japanese freighter Eiko-maru is destroyed near Odo Island, the Bingo-maru is sent to investigate, only to meet the same fate with few survivors. A fishing boat from Odo is also destroyed, with one survivor. Fishing catches mysteriously drop to zero, blamed by an elder on the ancient sea creature known as "Godzilla". Reporters arrive on Odo Island to further investigate. A villager tells one of the reporters that "something large is going crazy down there" ruining the fishing. That evening, a ritual dance to appease Godzilla is held during which the reporter learns that the locals used to sacrifice young girls. That night, a large storm strikes the island, destroying the reporters' helicopter, and an unseen force destroys 17 homes, kills nine persons and 20 of the villagers' livestock.
During a meeting of the Japan Self-Defense Forces (JSDF) for the potential return of Godzilla, Admiral Taizo Tachibana briefs cadets about Godzilla's first attack. A nuclear submarine is reported missing, which is later found to have been destroyed by Godzilla. Tachibana's daughter, Yuri Tachibana films a docudrama with her crew at Mt. Myoko, where a mysterious earthquake randomly ensues. The odd earthquake returns later that night burying a biker gang and leaving one surviving trucker who witnesses the monster, Baragon.
In 1996, after the death of SpaceGodzilla, Miki Saegusa travels to Birth Island to check on Godzilla and its adopted child, but finds the entire island destroyed. Godzilla appears in Hong Kong, covered in glowing lava-like rashes. It goes on a rampage, causing major collateral damage and killing thousands of civilians. A group of representatives from the Japan Self Defense Forces (JSDF) hires college student Kenichi Yamane, the grandson of Dr. Kyohei Yamane, to work at the center in an attempt to unravel the mystery of Godzilla's condition. Yamane suspects that Godzilla's heart, which acts as a nuclear reactor, is going through a nuclear meltdown. He theorizes that, when Godzilla's temperature reaches 1,200 degrees Celsius, it will explode with a force approximately "1,000 times greater than all nuclear weapons put together, a burst of power unseen since time began.
The opening credits scroll over an animated image of the character Bambi serenely grazing while the Call to the Dairy Cows from Rossini's opera William Tell (1829) plays in the background. After the credits, Bambi looks up to see Godzilla's giant foot coming down, squashing him flat (set to the final chord of The Beatles' "A Day in the Life" played at half-speed). After a moment, the closing credits scroll over the image of Godzilla's foot on top of a squished Bambi. At the very end, Godzilla's claws twitch once.
Une créature géante se manifeste dans la baie de Tokyo, avant de faire surface et de terroriser la ville. Le cabinet ministériel se réunit d'urgence, mais le Premier Ministre est incapable de prendre une décision. Les radiations mesurées sur le passage de la créature démontrent qu'elle est le triste produit d'une contamination. Plus tard, elle évolue et revient sous une forme encore plus monstrueuse, réduisant Tokyo en poussière. Devant l'ampleur de la menace, les États-Unis décident d'utiliser l'arme nucléaire sur le Japon si ce dernier échoue à éradiquer la menace, réveillant le spectre des bombardements d'Hiroshima et de Nagasaki. Une équipe de chercheurs se regroupe alors en marge des décisions du Cabinet pour déterminer comment éliminer le monstre, surnommé "Godzilla". La France et l'Allemagne finiront par s'en mêler à leur tours.
After a volcanic eruption on Daikoku Island, the Yahata-Maru Japanese fishing vessel is caught in strong currents off its shores. As the boat drifts into shore, the island begins to erupt, and a giant monster lifts itself out of the volcano. A few days later, reporter Goro Maki is sailing in the area and finds the vessel intact but deserted. As he explores the vessel, he finds all the crew dead except for one young man called Hiroshi Okamura, who has been badly wounded. Suddenly a giant Shockirus sea louse attacks him but he is saved by Maki who kills it with a cleaver.
In 1999, 45 years after Godzilla's first attack, Lieutenant Akane Yashiro, a mazer-cannon technician, is unable to kill a new member of Godzilla's species during her first fight. She is made a scapegoat for the military's losses during the battle and transferred to a desk job. During the battle, it was discovered that Godzilla is immune to mazer fire, rendering all of the Japanese military useless against it should it return. Scientists, including single father Tokumitsu Yuhara, are gathered to build a bio-mechanical robot from the original Godzilla's skeleton. Four years later, the cyborg Mechagodzilla, named Kiryu, is finished and inducted into the Japan Self-Defense Forces along with its human pilots as the Kiryu Squadron. Akane becomes the main pilot for Kiryu. However, memories of Akane's actions during the original fight still linger, and one of her squadron mates, Second Lieutenant Susumu Hayama holds her responsible for the death of his brother.
In the aftermath of Godzilla's attack on Tokyo and his later imprisonment at Mt. Mihara. a team of scientists discovers cells left in the rubble by the monster and collects them. A group of American militants takes a sample of their own. They attempt to escape with them, but are killed by a lone assassin codenamed SSS9, who steals the sample and departs. He boards a cruise liner and heads to the Republic of Saradia to deliver the cells to the Saradia Institute of Technology and Science. The president of the institute wants to use the cells to merge with genetically modified plants, hoping to transform Saradia's deserts to vast greenery and end the country's dependence on oil wells for wealth. Dr. Genshiro Shiragami and his daughter, Erika, are enlisted to aid with the ambitious project. However, a terrorist bombing destroys the institute's laboratory, ruining the cells and killing Erika.
In 1992, the United Nations establishes the United Nations Godzilla Countermeasures Center (UNGCC) to stop Godzilla. The remains of Mecha-King Ghidorah are salvaged from the ocean and used to create two anti-Godzilla machines. The first is a flying gunship called Garuda. The second and more powerful machine, modeled after Godzilla itself, is called Mechagodzilla.
Police Detective Shindo (Yosuke Natsuki) is assigned to guard Princess Selina Salno of Selgina (Akiko Wakabayashi) during the Princess' visit to Japan, due to a suspected assassination plot. Although Shindo is smitten with Selina's photograph, her plane never makes it to Japan, as it is destroyed by a bomb en route. At exactly the same time a meteorite shower draws the attention of Professor Murai (Hiroshi Koizumi), who along with his team of scientists strikes out into the wilderness to examine the largest of the meteors, which has magnetic properties.
Kiryu is undergoing repair modifications after its battle with Godzilla. Prime Minister Hayato Igarashi accepts Lead Scientist Yoshito Chujo's choice to replace the Absolute Zero Cannon with a powerful Tri-Maser.
News reporter Ichiro Sakai and photographer Junko Nakanishi take pictures of a wreckage caused by a typhoon. They uncover a strange, bluish-gray object in the debris, not knowing its significance. Later that day, a giant egg is discovered on the shore. The local villagers salvage it, and an entrepreneur of Happy Enterprises named Kumayama buys the egg from the local villagers. Instead of letting scientists study the egg, Kumayama wants to make it into a large tourist attraction. Later, Sakai and Nakanishi are informed that the strange object they found is extremely radioactive. (It is later hinted that this is a skin particle from Godzilla.
In 1992, journalist Kenichiro Terasawa (Kosuke Toyohara) is writing a book about Godzilla and learns about a group of Japanese soldiers stationed on Lagos Island in the South Pacific during World War II. They were unintentionally saved from a group of American soldiers by a mysterious dinosaur known as "Godzillasaurus" in February 1944. In 1954, the island was destroyed by a hydrogen bomb test and the radiation from the bomb mutated the dinosaur into Godzilla.
At the close of the 20th century, all of the Earth's kaiju have been collected by the United Nations Science Committee and confined in an area known as Monsterland, located in the Ogasawara island chain. A special control center is constructed underneath the island to ensure that the monsters stay secure, and to serve as a research facility to study them.