Doraemon constructed an underground cave hideout for the group, but Suneo strayed and went missing. Despite searching, everyone else managed to exit the cave, leaving Suneo behind. Soon after, they discovered that the entrance had collapsed, trapping Suneo inside. With no other option, they sought out an alternate entrance and stumbled upon a prehistoric land of dinosaurs. There, they met Vanho, a warrior who claimed to have located Suneo. But upon finding Suneo, they learned about Vanho's tribe's intentions to use them as specimens for study and eventually conquer Earth's surface.