"Kasuga no Tsubone" is her title given by the Imperial Court, and she was menoto (a wet nurse) of Iemitsu TOKUGAWA, the third Shogun in the Edo bakufu (Japanese feudal government headed by a shogun).
-春日局」とは朝廷から賜った称号で、江戸幕府3代将軍・徳川家光の乳母。