Princess Kaoruko (馨子内親王, Kaoruko-naishinno, 1029–1093), also known as Saiin-no Kōgō (西院皇后), was an empress consort (chūgū) of her cousin Emperor Go-Sanjō of Japan.^[1]

She was the daughter of Emperor Go-Ichijō. She served as Saiin (priestess) from 1032 until 1036. She married her cousin the future emperor in 1051. In 1068, her husband became emperor. She had no children.

After the death of her husband, she became a Buddhist nun under the name Saiin-no Kōgō (西院皇后). ^[2]