Has Japan ever been ruled by a foreign country?

Japan has never been ruled by a foreign country. However, some parts of Japan were occupied by foreign powers at different times in its history. For example, Hokkaido was occupied by Russia in the late 18th century, and Okinawa was occupied by the United States from the end of World War II until 1972. However, these occupations did not result in Japan becoming a colony of any other country.