Decades after the war for the survival of our species, in the year 2020, a base has suddenly appeared in the Atlantic Ocean. The name of the base: "The Empire of Atlantis". The elite of Atlantis, made up of human-beast hybrids, control a gigantic weapon called the High Beast, which is armored with an Orichalcum that prevents any kind of attack, and quickly overrun the world.

Meanwhile, Dr. Shifukan, who has been researching the Getter Line, realizes a way to defeat the High Beast's Orichalcum, and develops a humanoid weapon with this ability, the Getter Robo. The only way to defeat the perfect Orichalcum is to play mahjong!

Banko Benimaru, Takeo Midorikawa, and Tsutsuno Byakuya are chosen to be Getter pilots, and throw themselves into the battle to protect the Earth.