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.

During World War II, the Japanese military established a secret underground laboratory in Tokyo. Three Olympic-level athletes were selected to undergo a process that would turn them into Jinra-go, superhuman armored soldiers. By March 1945, one of the soldiers had been completely transformed into the half man/half machine ultimate soldier called Mikadroid. But American B-29s firebomb the city and, while the two super soldiers manage to escape, Mikadroid and the lab are apparently destroyed. 45 years pass, Tokyo is rebuilt, and old secrets are forgotten. The site is now home to a complex that includes the Discoclub Layla. The disco’s patrons dance late into the night, unaware that a faulty basement generator has reactivated Mikadroid and the cyborg now prowls the basement levels, killing anyone in its path...

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.

Reporter Goro Maki stumbles upon scientists conducting weather experiments on Sollgel Island in the South Seas. He discovers the island is inhabited by giant mantis and a woman named Saeko who's been cast away since the death of her father. The pair soon find a helpless infant monster that Godzilla must adopt and learn to raise as one of his own.

In feudal Korea, a group of starving villagers grow weary of the orders handed down to them by their controlling king and set out to use a deadly monster under their control to push his armies back.