Dr. Tanaka informs Tony that a mysterious epidemic has broken out near the Arc Station. The rampant and deadly disease appears unstoppable, and Tony initiates his own investigation into the cause. Meanwhile, the Self Defense Forces reconnaissance satellites are acting up, and Nagato Sakurai visits Iron Man to ask for his help. Stark and Sakurai join forces, when they discover the Zodiac Mech Aquarius may be behind both.

The plutonium needed to prime the Arc Station is stolen and Tony must don the Iron Man armor and fight against Dio. The two Iron Men must fight to the death, with the fate of Japan hanging in the balance.

"Iron Man is dead!" Dr. Chika Tanaka hears these astounding words from Yinsen's own lips. Meanwhile, the seriously wounded Tony Stark survives with the help of Nagato Sakurai and must devise a way to defeat Dio once and for all. But what awaits the arrival of Iron Man is not only Dio, but also four Iron Man Sigma models as well. How will Tony Stark overcome the hopeless situation he finds himself in?