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.

A young boy named Taro develops a curious preoccupation with his pet turtle named Gameron, to whom he constantly encourages to grow. After getting into trouble for bringing his turtle to school and neglecting his studies, Taro winds up in the company of two bumbling gangsters as they flee from the authorities. While hiding out in the sewer, Taro is delighted to find that his turtle has suddenly grown to 99 cm in length. The sight of the giant turtle, however, frightens the gangsters into the welcoming arms of the police. Assuming that Taro had been kidnapped by the two thieves, the authorities return to collect the boy, who is nowhere to be found.

Returning home from a party one night, Jun and company become lost in the outskirts of Tokyo. When Ippei and Takehara accidently stumble into a marsh, the group seeks refuge in a nearby Western-style mansion to help keep the two men warm.