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.

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.

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.

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.

In 1966, five infant children were kidnapped by an alien group known as the Alien Hunters for the Reconstructive Experiment Empire Mess, who wanted samples of humans from Earth to experiment on. The children were rescued by Mess' arch enemy, the Flash alien race, which took each one to a different planet of the Flash solar system for training. Each child was trained separately in a range of superpowers that will allow them to fight Mess, their bodies also adapted to the atmosphere of the Flash Solar System making them gain special abilities. When they finally return to Earth in 1986 to combat Mess, who is now trying to invade it, they use the opportunity to search for their birth parents.