“In 1924, Hirohito, still a regent, married Kuni-no-miya Nagako, daughter of a collateral house of the imperial family. As was appropriate at the time, the marriage between Hirohito and Nagako was arranged by formal introduction rather than being a ‘love match’. Emperor Hirohito made one important break with custom regarding married life, however: the concubine system was abolished. Hirohito, with his commitment to monogamy, did not miss the ladies-in-waiting.
“… Even when his advisors, after Nagako had given birth to four daughters but no son several years into their union, urged him to make use of the concubines to produce an heir to the throne, Hirohito refused. Nagako gave birth to Akihito, the heir, on 23 December 1933.”
– The People’s Emperor: Democracy and the Japanese Monarchy, 1945-1995, by Kenneth J. Ruoff, 2001