The evil organization DISSOLUTION has entered the final stage of its plan to conquer Fontaine and dominate Japan. But at that moment, a new threat arrives from across the sea—SUPERLADY! She appears to stop DISSOLUTION's evil scheme of world domination. Dr. Unknown and Satoru Mika devise a new strategy to destroy SL, the organization's latest threat. Though DISSOLUTION's previous underlings have all been defeated, leaving them seemingly powerless, they have now succeeded in creating a new weapon: Mecha SL. And now, this mechanical warrior awakens at the forefront of evil!