The games are mostly set in a near future and more specifically in Planetokio, which it is a number of floating cities full of life like the old Japan. The city is attacked by the Collect Aliens that got a personal shield that allow them to receive no harm. The protagonist of the series is a blue-haired boy named Iken, whose peaceful life in Planetokio is often interrupted by alien robots and monsters. In most games, Iken must defeat the aliens and foil any world domination plans.