While mining a train tunnel between Tokyo & Osaka, a construction crew unearths a strange object from within a huge underground cavern. Unable to identify the object, Jun and Yuriko venture into the tunnel to further investigate. In the meantime, Ippei and a reporter, with the help of a young boy named Liro, discover that the object is the egg of the giant bird called Litra. According to ancient legend, when Litra's egg is found, the giant monster Gomess will appear to destroy the Earth and consequently, Litra will rise up to defend against it.