Ghidorah, the Three-Headed Monster

A mysterious extraterrestrial being resembling Godzilla rapidly approaches Earth. The monster, dubbed SpaceGodzilla, lands to challenge the King of the Monsters.

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.

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.

Gamera escapes from his rocket enclosure and makes his way back to Earth as a giant opal from New Guinea is brought back to Japan. The opal is discovered to have been an egg that births a new monster called Barugon. The creature attacks the city of Osaka by emitting a destructive rainbow ray from his back, along with a freezing spray capable of incapacitating Gamera.

Gaira, a humanoid sea beast spawned from the discarded cells of Frankenstein's monster, attacks the shores of Tokyo. While the Japanese military prepares to take action, Gaira's Gargantua brother, Sanda, descends from the mountains to defend his kin. A battle between good and evil ensues, leaving brothers divided and a city in ruins.

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.

An independent group of researchers called the Godzilla Prediction Network (GPN) actively track Godzilla as he makes landfall in Nemuro. Matters are further complicated when a giant meteor is discovered in the Ibaragi Prefecture. The mysterious rock begins to levitate as it's true intentions for the world and Godzilla are revealed.

With the Gyaos re-emerging, Gamera's ties to humanity have been severed with his bond to Asagi broken. Nagamine and Asagi investigate while an orphaned girl named Ayana discovers a new creature she names Iris. Nagamine and Asagi must reach Ayana before she takes her revenge on Gamera, who she blames for the death of her family.

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.

Following their explosive showdown, Godzilla and Kong must reunite against a colossal undiscovered threat hidden within our world, challenging their very existence – and our own.