After watching a film that features Mechapolis, a city of machines, Arale and her friends from Penguin Village wish that such a place truly existed. That very night, every one of the children is carried off and wakes up in a real Mechapolis. There they discover that for this one night, any wish they make will come true, and the results are far from simple. A comedy movie in the Dr. Slump franchise, full of slice-of-life silliness.