Baby Godzilla hatched from an egg that was laid in a pteranadon nest on Adonoa Island. While Japanese scientists were carrying the unhatched egg to a helicopter, Rodan, who hatched from an egg in the same nest, attacked the scientists, until Godzilla rose from the sea and killed Rodan. Since Baby Godzilla's egg was placed in the same nest as Rodan, Rodan believed that Baby Godzilla was its brother, and would attack anyone near it. Godzilla, though, attacked Rodan because, afterall, it was his son. The United Nations Godzilla Countermeasures Center (UNGCC) decided to use Baby Godzilla to lure the real Godzilla to Mechagodzilla, so Mechagodzilla could kill the king of the monsters for good. After Godzilla defeated Mechagodzilla, he and Baby Godzilla moved to Birth Island.