The story of an heir to the secret formula of the Nazi V4 project and his struggle against a Neo-Nazi organization. Invited to Nazi Germany during the second World War, Hitler asks Dr. Asagumo to collaborate in researching the new weapon “Big X”. Concerned about the possible effects of this weapon, Dr. Asagumo intentionally and repeatedly delays the progress of the research, conspiring with his co-researcher, the mischievious Dr. Engel. Immediately before Germany is defeated by the Allies, Dr. Asagumo is shot to death by the German army, however not before implanting a card inscribed with the secret of Big X into his son, Shigeru. An organization claiming an alliance with the Nazis appears, steals the card from Shigeru, who now lives in Tokyo, and completes the Big X project, which is revealed to be a drug that can expand the human body without limitation. Dr. Engel’s grandson has joined the Nazi Alliance. Recovering Big X from the enemy, Shigeru’s son Akira fearlessly challenges the Nazi Alliance and Hans Engel, who are plotting to conquer the world.