He publicly made controversial statements about the responsibility of Japan and its then-reigning Emperor for World War II, and survived a retaliatory assassination attempt in 1990 by a right wing fanatic.
During World War II the Japanese authorities suspected Motoshima of espionage because he was a descendant of Kakure Kirishitans and born out of wedlock.
However, facing much criticism, Motoshima lost the 1995 election to Liberal Democratic Party-endorsed opponent, Iccho Itoh, and retired from politics.
In late 1988 during his third mayoral term, news that the Shōwa Emperor was gravely ill and not expected to live long had put Japan into a somber mood.
Furthermore, many extreme right-wing groups converged on Nagasaki and demonstrated in the streets with more than eighty speaker trucks calling out for divine retribution upon the mayor.