The Princess Teruko, the lawful wife of Mitsusada TOKUGAWA who was the second lord of Kishu Domain, was Masako's aunt, and the Princess Kenshi, the lawful wife of the fourth Shogun Ietsuna TOKUGAWA was her aunt, and the Princess Zoushi, the lawful wife of the ninth Shogun Ieshige TOKUGAWA was her niece.
紀州藩第2代藩主・徳川光貞正室の照子女王は伯母、第4代将軍・徳川家綱正室の顕子女王は叔母、第9代将軍・徳川家重正室の増子女王は姪に当たる。