The Empress succeeded to the throne at the age of seven as Imperial Princess Okiko after suddenly receiving the title Princess by Imperial order from her father, Emperor Gomizunoo, who was angry about the Edo bakufu (Japanese feudal government headed by a shogun) after the Shie Incident in 1629, and another incident, Shogun Iemitsu TOKUGAWA's educator, Kasuga no Tsubone entered the Imperial Palace without any official position.
寛永6年（1629年）の紫衣事件や将軍徳川家光の乳母春日局が無官のまま参内した事件に、江戸幕府への憤りを覚えた父の後水尾天皇から突然の内親王宣下と譲位を受け、興子内親王として7歳で践祚。