A father hides a weapon's secret inside his own son's body, then dies before he can explain why. Fifty-nine episodes later, you're watching a kid run from Nazi remnants, Soviet spies, and his own father's ghost, all hunting the one thing implanted in his chest. This is pulp sci-fi from an era when anime could be utterly unhinged without irony, where the plot keeps escalating because nobody told the writers to stop.
A scientist's deadly secret carries forward two decades after World War II ends. Dr. Asagumo spent the war sabotaging a Nazi superweapon called Big X from the inside, then hid its blueprints in the most unexpected place: his own son's body. When the secret resurfaces in 1960s Tokyo, it triggers a chain reaction nobody could have predicted. A shadowy organization resurrects the Nazi cause and hunts down the plans, determined to finish what Hitler's regime started. Now Shigeru finds himself at the center of an international conspiracy, caught between forces who want Big X completed and those desperate to keep it buried forever. What unfolds is a high-octane race against time where Cold War tensions collide with remnants of fascism. The show balances pulpy action sequences with genuine stakes: in a world still healing from the last global conflict, another superweapon falling into the wrong hands could reshape everything. Expect spy intrigue, underground bases, and mounting danger as Shigeru learns what his father truly sacrificed and why keeping Big X hidden might be impossible.