I just watched the original Japanese release of "Frankenstein Conquers The World" (Known in Japan as "Frankensein Vs. Baragon" and sometimes, "Frankenstein Vs. The Giant Devilfish").
It's surely one of the strangest premises for a Frankenstein film , even for a Japanese Horror movie in general , and it's radically different from the better known American release.
With Hitler's defeat , and eventual death , upon him , SS Officers steal the still - beating heart of the original Frankensten monster from an anti - Fascist German Scientist. The heart is transported , by submarine , to Japan . The bombing of Hiroshima soon follows . Amazingly , some children , left orphaned and homeless in the attack , not only live , but prove to possess a strong resistance to radiation. 15 years later , one boy , easily in his 20's , but only moderately affected by age , lives as a wild beast , eating dogs , cats , chickens , hogs , etc. He is captured by sympathetic Japanese and American Scientists , eager to study Frankenstein's heart. It's too late , the wild boy has eaten it (Though this is mentioned nowhere in the script.). He soon becomes more Frankenstein - like in appearance , and grows to staggering heights . Escaping from the enormous cell in which he was chained up , he terrorizes the beautiful mountainside . The photography , I might add , is also beautiful (If you think Japanese Horror / Sci - Fi flicks had no production values , see this , Atragon , Dagora , Matango , The Mysterians , and other , more adult - oriented features....).
In time , the giant Frankenstein monster takes on the appearance of a caveman ,with a flat head , black hair , and angular forehead , reminiscent of the classic Universal Studios prototype. The Army is out to destroy him , but , after fighting , and winning , against the strange , horned , luminescent giant reptile , Baragon , that can burrow his way under the ground , Frankenstein becomes , maybe for the first time , ever , a hero , but , his work is not yet done. A giant octopus appears , at the very end (For no good reason , I might add). Frankenstein succeeds in defeating the octopedian creature (Don't ask me why he appeared on mountainous terrain , but , like Ed Wood deduced , you got an octopus , you might as well use it. The monster - hero is left to go in peace , tiring of the destruction he's caused.
Baragon would turn up , again , in "Destroy All Monsters " and "Gamera vs. Baragon" (Don't know how they pulled that one off , as Gamera was not a Toho Studios property.).
A proposed sequel to this movie became "War of The Gargatus" , with no discernible connection to the Frankenstein legend, nor even the previous film. The King of Cool , Russ Tamblyn , plays one of his last serious roles for a LONG time.