Mazinger Z is an enormous super robot, constructed with a fictitious metal called Super-Alloy Z, which is forged from a new element (Japanium) mined from a reservoir found only in the sediment of Mt. Fuji, in Japan. The mecha was built by Professor Juzo Kabuto as a secret weapon against the forces of evil, represented in the series by the Mechanical Beasts of Dr. Hell (Cit.Wikipedia)
Man I remember watching this show waaaaay back when I was young! I even had the plastic toy that stood about three feet tall and shot plastic missles from a spring loaded hand before such things were considered unsafe. Ah, the good old days!