When reptile eggs disappoint Uiba Shikatani, her father's gift of a large, striped egg brings hope. This egg hatches into a green dinosaur named 'Muka-Muka' who can only utter those words. As Muka-Muka gains fame, the town's professor and his eccentric inventions, like a time machine, draw attention. The machine transports the Shikatani family and others back to a prehistoric era, leading to encounters with dinosaurs and magical creatures on a thrilling journey.