Around 1108, she was ordered by the Chiten (person in power) at that time, Emperor Shirakawa to make bridal entry in to the Imperial Palace to the young Emperor Toba, who was eight years younger than her, although her father, Tadazane kept rejecting the order from the In, he accepted it positively after Emperor Toba himself recommended Taishi enter into the Imperial Palace after 1113.
天仁元年（1108年）頃、八歳年下の幼帝・鳥羽天皇に入内するよう時の治天白河天皇に命ぜられ、父忠実は院の要請を固辞したが、永久の頃（1113年以後）、鳥羽天皇自身が泰子入内を勧めると、あろうことか積極的に応対した。