Humanity finally rids themselves of Godzilla, imprisoning him in an icy tomb in the South Pole. All is peaceful until various monsters emerge to lay waste to Earth's cities. Overwhelmed, humanity is seemingly saved by a race of benevolent aliens known as Xiliens. But not all is what it seems with these bizarre visitors. If humanity wishes to survive, they must reluctantly resurrect their most hated enemy, Godzilla.

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.

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.

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.

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.

In an alternate timeline the original Godzilla is never defeated and repeatedly reemerges to feed on Japan's energy sources. A new inter-dimensional weapon called the Dimension Tide is created with the intent of eliminating Godzilla. However, the new weapon might also serve as a gateway to something far more sinister.

Godzilla has become a distant memory for Japan when the destruction of a US submarine raises alarms for Admiral Tachibana. His estranged daughter Yuri investigates the legend of the guardian monsters, who must rise to protect Japan against the vengeful spirits within Godzilla that seek to destroy both the nation and its people for the suffering they inflicted in the Pacific conflict.

Originally released in Japan as "The Return of Godzilla" in 1984, this is the heavily re-edited, re-titled "Godzilla 1985". Adding in new footage of Raymond Burr, this 16th Godzilla film ignores all previous sequels and serves as a direct follow-up to the 1956 "Godzilla King of the Monsters", which also featured scenes with Burr edited into 1954's "Godzilla". This film restores the darker tone of the original, as we witness the nuclear destruction of giant lizard terrorizing Japan.

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.

JSDF pilot Akane has a fateful encounter when a new Godzilla emerges in Tateyama. As a countermeasure, a cyborg named Kiryu is constructed from the remains of the original. The machine is discovered to harbor the restless soul of the original monster as Akane must learn to find value in her own life as well.

Mothra and her fairies return to Japan to warn mankind that they must return Kiryu to the sea, for the dead must not be disturbed. However Godzilla has survived to menace Japan leaving Kiryu as the nation's only defense.