Tokugawa Masako (徳川 和子, November 23, 1607 – August 2, 1678), also known as Kazu-ko,[1] was empress consort of Japan as the wife of Emperor Go-Mizunoo.

Through collaboration with her parents, Oeyo and Shogun Tokugawa Hidetada, she was a prominent and influential figure within the politics and culture of the Edo Period.

In a rare break with tradition, Masako's daughter, Imperial Princess Onna-Ichi-no-miya Okiko, succeeded her father in her own right as Empress Meishō, albeit at the age of five.

Masako used her wealth to bring together the two capitals of Edo and Kyoto, as well as helping to maintain the high standards of the court.

It is perhaps more likely, though, that Go-Mizunoo abdicated due to the fallout over the "Purple Robe Incident", which had caused a serious political conflict between him and Tokugawa Iemitsu, the new Shogun.