Japan is in the interesting position of having an Emperor as head of state but not being an Empire, instead they're the State of Japan. After the Second World as part of the governmental and societal reforms the Emperor made the Imperial Rescript on the Construction of a New Japan part of which involved his renouncing any claim to being a living god. To simplify the situation of an Emperor without an Empire do people think it would have been possible if someone like MacArthur had gotten the idea into their head for the Emperor to have been demoted to a King and it become the Kingdom of Japan?