Archeologist Tetsuya Randou leads his family on an adventure around the world to find out the legend of Quaschika, which supposedly hides an unfounded treasure. At the same time the Goblin Clan, who normally live underground, is also trying to find the treasure of Quaschika for their own purposes. To help fight off the Goblin Clan during their adventure, the Randou family has the giant robot Acrobunch, formed by the vehicles each family member pilots.