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.

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.

Mining engineer Shigeru investigates the disappearance and death of his fellow coworkers when prehistoric nymphs are discovered emerging from the mines. After an attack on the local village, Shigeru heads deeper into the mines only to make a more horrifying discovery in the form a prehistoric flying creature. Soon a second monster appears as the two converge in Fukuoka.

A man forced to bear power and stripped of humanity. A woman skeptical of happiness. Takeshi Hongo, an Augmentation made by SHOCKER, and Ruriko Midorikawa, a rebel of the organization, escape while fighting off assassins. What’s justice? What’s evil? Will this violence end? Despite his power, Hongo tries to remain human. Along with freedom, Ruriko has regained a heart. What paths will they choose?

In order to counter the rapidly increasing organized crime, the development of Polymar Suits resumed under the direction of the newly inaugurated police superintendent. But when three of the test version Polymar Suits are stolen, former street fighter and current detective Takeshi Yoroi is tasked with recovering them and the invincible hero Hurricane Polymar is born!

The U.N.G.C.C. (United Nations Godzilla Countermeasure Center) recovers the remains of Mecha-King Ghidorah and construct Mechagodzilla as a countermeasure against Godzilla. Meanwhile, a giant egg is discovered along with a new monster called Rodan. The egg is soon found to be none other than an infant Godzillasaurus.

The Changeman must work with an earthquake institute to prevent Earth from being destroyed in a sea of fire by the Gozma.

After a Space Beast throws them off Shuttle Base, the Changeman scramble to get their ship back as Sayaka tries to protect it from the inside.

The Flashman find themselves protecting a puppy targeted by Mess due to it being the weakness of a chimera Beast Warrior.

The Turboranger must prevent a Bouma from unsealing his father in order to utilize his hellfire to burn the Earth.

The Book of Ruin, which should have been sealed, is released along with the mysterious immortal swordsman, Bacht. Darkness overflows from the book, causing the real world and Wonder World to disappear. Touma Kamiyama, alongside members of the Sword of Logos, challenge Bacht to a decisive battle in order to stop this situation.

Big Rally! Titan Boy! is the second movie of Choushinsei Flashman. It is a theatrical edit of episodes 15 to 18 (The Giant Robo is Worn Out, The Human Minimini Plan, The Mysterious Giant Reckless Car! and Big Turnaround! The Transforming Robo) with new and extended scenes.