Sadako Kujō (九条節子, Kujō Sadako; 25 June 1884 – 17 May 1951), posthumously honoured as Empress Teimei (貞明皇后, Teimei Kōgō), was the wife of Emperor Taishō and the mother of Emperor Shōwa. Her posthumous name, Teimei, means "enlightened constancy". She was also the paternal grandmother of Emperor Emeritus Akihito, and the paternal great-grandmother of Emperor Naruhito.
Source: “Empress Teimei”, English Wikipedia (CC BY-SA 4.0), excerpt