Godzilla vs. King Ghidorah (1991)

In the year 2204, a submarine discovers the seemingly lifeless two-headed body of King Ghidorah at the bottom of the Sea of Okhotsk. Inside the submersible, a young woman confirms that Ghidorah had fought Godzilla at the end of the 20th century.

One night during the summer of 1992, an enormous unidentified flying object is observed at various points over Japan, including Tokyo. While the news media attempts to explain the strange phenomenon, Kenichiro Terasawa, a writer for Super Mystery Magazine MU, instead sets out to interview an old man who'd made news for protesting a dinosaur exhibit at a museum. The old man tells Terasawa a story of how, in 1944, a dinosaur saved his garrison from an American attack at Lagos Island, a story which is later confirmed by Yasuaki Shindo, the former Lagos garrison commander and present head of the Teiyo Group, a massive corporation he'd established in postwar Japan. In the course of his research, Terasawa develops a hypothesis that the dinosaur was exposed to radioactive fallout from H-bomb tests in 1954, irradiating the creature and transforming it into Godzilla.

Meanwhile, the JSDF tracks the UFO's movements over the Pacific Ocean, and it's discovered that the ship had visited Godzilla, who has been dormant since receiving a large dose of Anti-Nuclear Energy Bacteria and a battle with Biollante. The UFO soon lands at Mount Fuji and the inhabitants introduce themselves to the Japanese government: they are the westerners Wilson and Glenchiko, and the Japanese woman Emmy Kano, all three delegates from 2204 A.D. They reveal they've traveled through time to warn Japan of its grave future: due to industrialization and nuclear power, Godzilla will reappear and destroy Japan once and for all. As evidence, they present the book that Terasawa will write in the future, entitled The Birth of Godzilla. With the government's agreement, the Futurians organize a trip back to Lagos Island in 1944 to transport the Godzillasaurus to the Bering Sea, where it won't be mutated by the H-bomb, thus preventing Japan's destruction. In addition to Emmy and M11, the futurians' android, three people from the 20th century are invited to oversee the mission: Terasawa, Miki Saegusa, and Professor Mazaki, a paleontologist and one of Terasawa's associates. Also making the trip are three Dorats, the Futurians' genetically-engineered pets, ostensibly to provide companionship to the five time travelers.

The group from 1992 successfully arrives at its historical destination, where they secretly observe the battle between Imperial Japanese forces and American marines. The depleted Japanese garrison is overwhelmed and almost eliminated by the U.S. landing unit. The furious battle, however, disturbs the Godzillasaurus. The Japanese soldiers retreat while the Americans turn their attention to the angry dinosaur. It tramples the Americans, who call for backup. Offshore, their destroyers shell the island and gravely injure the Godzillasaurus in the process, but not before it finishes off its land-based attackers. Miki positively identifies the dinosaur as Godzilla, so the time travelers begin plans for teleportation. They advance in time roughly one week and observe the Japanese unit's departure, including Lt. Shindo's tearful farewell to the dinosaur, whom he credits with saving his life. M11 then teleports the dinosaur to the bottom of the Bering Sea. As the group prepares to time warp back to 1992, Emmy clandestinely releases the Dorats onto the island.

Back in 1992, it's confirmed that the mission was successful and Godzilla has disappeared. Glenchiko, however, reveals that the unforeseen has occurred: at the moment Godzilla disappeared, another monster called King Ghidorah appeared over the Pacific, heading for Japan. The three-headed creature ravages Fukuoka and begins moving northward through Kyushu. While the government struggles to grasp the connection between the two monsters, Miki concludes that King Ghidorah must have been created by the Dorats' exposure to the nuclear tests at Lagos Island, thus implicating the Futurians in the new monster's rampage.

Deeply upset by the latest turn of events, Emmy comes clean to Terasawa about the true nature of the Futurians' visit. In her future, Japan has become the preeminent world superpower, thanks to its meteoric economic expansion. In time, she says, the nation will become so corrupt and wealthy that it will buy entire countries and even continents. To counteract its domination, people from around the world unite to form the Equal Environment Earth Union, the group to which the Futurians belong. Extremists Wilson and Glenchiko, along with moderate Emmy, stole the time machine to create King Ghidorah and to use it to extort the 20th century Japan, preventing its future ascension. The story about Godzilla's revival and subsequent destruction of Japan was merely a lie to force the Japanese people to cooperate. In Emmy's view, however, Wilson has gone too far, as he's now using King Ghidorah to completely destroy Japan.

The government desperately formulates a plan to mutate the Godzillasaurus into Godzilla, who they perceive to be the only force powerful enough to defeat King Ghidorah and the Futurians. Despite the protests of certain civilian factions, Shindo's Teiyo Group provides a submarine armed with nuclear warheads for the task, dubbed "Operation G". Shortly thereafter, Miki senses Godzilla—not the Godzillasaurus—at the bottom of the Bering Sea. Emmy proposes that the dinosaur might have come in contact with radioactive material; Terasawa discovers that a nuclear submarine had previously disappeared in the Bering Sea where the Godzillasaurus had been transported. He realizes that this must have mutated the dinosaur, and thermal satellite images indeed confirm the existence of the 80-meter Godzilla where Miki had sensed him. But before they can warn the government, Godzilla destroys the submarine and consumes its energy, growing even larger in size and strength. Freshly energized, Godzilla comes ashore in Hokkaido.

Wilson and Glenchiko, realizing that the birth of Godzilla was an unavoidable event in the 20th century, send King Ghidorah to combat Godzilla. The monsters trade devastating blows, but Ghidorah gains the upper hand as it strangles Godzilla. Hundreds of miles away, on the Futurian UFO, Emmy, Terasawa and a reprogrammed M11 sabotage the monster control device. Godzilla seizes the opportunity and pummels his uncontrolled three-headed foe. With a supercharged atomic ray, Godzilla decapitates Ghidorah's middle head. King Ghidorah flies away, but succumbs to its wounds and crashes into the Sea of Okhotsk. Emmy confronts Wilson, whose plan has been foiled. Unbeknownst to her, however, Wilson plans to escape to the 23rd century. King Ghidorah may have lost, but Wilson reasons that the new Godzilla will finish off the ailing nation. Emmy, Terasawa, and M11 temporarily subdue Wilson and Glenchiko and escape the UFO in the smaller KIDS time-transport ship. From there, M11 teleports the mothership—with Wilson and Glenchiko aboard—to Hokkaido, where it's destroyed by Godzilla.

Godzilla is engaged by a Maser brigade in Sapporo but it fast becomes apparent that the nuclear monster is unstoppable. M11's computer simulations show that Godzilla will not stop until he strikes Tokyo. Emmy proposes returning to her time to use 23rd century technology to revive King Ghidorah, with which she'll defend 20th century Japan. In the meantime, Godzilla reaches and lays waste to Tokyo. In Shinjuku, in a penthouse atop his skyscraper, Shindo watches helplessly as his former savior destroys the city that he'd helped rebuild. Godzilla in turn sees Shindo, and the two share a moment of recognition. Shindo accepts his fate as Godzilla incinerates him with his atomic ray.

The sky flashes as Emmy arrives from the future. Her mission was successful: King Ghidorah had remained alive long enough for her government to convert it into the cybernetic being Mecha-King Ghidorah. The enormous monster engages Godzilla in battle in the midst of Shinjuku's towering skyscrapers. Even aided with future technology, Mecha-Ghidorah is no match for Godzilla's heat ray. Emmy arms the Godzilla Grip system, grappling cables which ensnare Godzilla. The mechanical dragon rises into the sky, with Godzilla in tow, and flies out to sea. Godzilla's ray tears through Ghidorah's wings and both monsters crash into the deep. The KIDS transport erupts from the ocean, revealing to her 20th century friends that Emmy had survived the battle. Before warping back to the the future, Emmy privately bids farewell to her country, and to Terasawa, whom she identifies as one of her ancestors.

At the bottom of the sea, entangled in Mecha-King Ghidorah's remains, Godzilla awakens.