In the space year 6216 (1422 in the original Arcade version), the Fantasy Zone was cast in panic at the collapse of the interplanetary monetary system. The Space Guild reveals the plans of the planet Menon, whose forces are stealing the other planets' currencies to fund a huge fortress in the Fantasy Zone. Opa-Opa is sent to the Menon system after they stole supplies from other systems. It is revealed that Opa-Opa's father is the leader of Menon.