Lupin is caught in a flash of blinding light and finds himself in Showa era Japan circa 1930. He finds that he is the thief "Golden Mask" being pursued by Inspector Namikoshi who looks like Zenigata. "Golden Mask" sets his sights on a national treasure from the Imperial Museum but he must contend with private detective extraordinaire, Akechi Kogoro and the "Black Lizard" who resembles Fujiko.