Japan is thrown into a panic after several ships are sunk near Odo Island. An expedition to the island led by Dr. Kyohei Yamane soon discover something far more devastating than imagined in the form of a 50 meter tall monster whom the natives call Gojira. Now the monster begins a rampage that threatens to destroy not only Japan, but the rest of the world as well.

Two fishing scout pilots make a horrifying discovery when they encounter a second Godzilla alongside a new monster named Anguirus. Without the weapon that killed the original, authorities attempt to lure Godzilla away from the mainland. But Anguirus soon arrives and the two monsters make their way towards Osaka as Japan braces for tragedy.

The advertising director of Pacific Pharmaceuticals, frustrated with the low ratings of their sponsored TV program, seeks a more sensationalist approach. He orders his staff to Faro Island to capture King Kong for exploitation. As Godzilla re-emerges, a media frenzy generates with Pacific looking to capitalize off of the ultimate battle.

Journalists Ichiro Sakai and Junko cover the wreckage of a typhoon when an enormous egg is found and claimed by greedy entrepreneurs. Mothra's fairies arrive and are aided by the journalists in a plea for its return. As their requests are denied, Godzilla arises near Nagoya and the people of Infant Island must decide if they are willing to answer Japan's own pleas for help.

After a meteorite unleashes a three-headed beast upon Tokyo, Mothra tries to unite with Godzilla and Rodan to battle the extraterrestrial threat.

Astronauts Glenn and Fuji investigate Planet X and encounter mysterious aliens known as the Xiliens, who ask Earth's people to help save their world from "Monster Zero". In exchange for borrowing Godzilla and Rodan, the Xiliens offer a cure for cancer. As Glenn investigates, he develops a romance with Miss Namikawa and uncovers the Xilien's true intentions.

Searching for his brother, Ryota stows away on a boat belonging to a criminal alongside two other teenagers. The group shipwrecks on Letchi island and discover the Infant Island natives have been enslaved by a terrorist organization controlling a crustacean monster. Finding a sleeping Godzilla, they decide to awaken him to defeat the terrorists and liberate the natives.

Reporter Goro Maki stumbles upon scientists conducting weather experiments on Sollgel Island in the South Seas. He discovers the island is inhabited by giant mantis and a woman named Saeko who's been cast away since the death of her father. The pair soon find a helpless infant monster that Godzilla must adopt and learn to raise as one of his own.

At the turn of the century, all of the Earth's monsters have been rounded up and kept safely on Monsterland. Chaos erupts when a race of she-aliens known as the Kilaaks unleash the monsters across the world.

Ichiro Miki is a child living in the industrial district of Kawasaki, where his parents' constant struggle to make ends meet often leaves the schoolboy alone. Constantly teased by a bully nicknamed Gabara, his only friends are toy consultant Shinpei and fellow classmate Sachiko. Ichiro turns to escapist dreams of Monster Island where he befriends the equally bullied Minilla.

An ever evolving alien life-form arrives on a comet from the Dark Gaseous Nebula and proceeds to consume pollution. Spewing mists of sulfuric acid and corrosive sludge, neither humanity nor Godzilla may be able to defeat this toxic menace.

Manga artist Gengo Odaka lands a job with the World Children's Land amusement park only to become suspicious of the organization when a garbled message is discovered on tapes. As Gengo and his team investigate, Godzilla and Anguirus quickly decipher the message and begin their own plan of action.

Inventor Goro Ibuki creates a humanoid robot named Jet Jaguar. It is soon seized by an undersea race of people called the Seatopians. Using Jet Jaguar as a guide, the Seatopians send Megalon as vengeance for the nuclear tests that have devastated their society.

An Okinawan prophecy that foretells the destruction of the Earth is seeming fulfilled when Godzilla emerges to return to his destructive roots. But not all is what it seems after Godzilla breaks his ally Anguirus's jaw. Matters are further complicated when a second Godzilla emerges, revealing the doppelgänger as a mechanical weapon.

A submarine expedition to salvage the remains of Mechagodzilla is thwarted by a massive dinosaur named Titanosaurus. An Interpol investigation leads biologist Ichinose to uncover the work of Dr. Mafune and his mysterious daughter Katsura. Aligned with the Black Hole Aliens, Katsura's life becomes entwined with the resurrected machine.