Princess Yasuko
Princess Yasuko or Princess Teishi (媞子内親王, Teishi (Yasuko) Naishinō; 1076–1096), later Ikuhomon'in (郁芳門院) was an honorary Empress of Japan to her brother Emperor Horikawa. She was the first daughter of Emperor Shirakawa and Fujiwara no Kenshi (1057–1084), and the sister of Emperor Horikawa. She served as the Saiō of her father Emperor Shirakawa in 1078–1086. In 1087, her father abdicated in favor of her brother Emperor Horikawa. In 1091, she was appointed Honorary Empress to her twelve-year-old brother the Emperor. It was rare for a sister to be appointed Empress of her own brother, but she was actually his nurse and adoptive mother, their mother having been dead since he was five. She retired as her brother's empress in 1093. Notes

Japanese princesses
Japanese empresses consort
1076 births
1096 deaths
Saikū
Japanese Buddhist nuns
11th-century Buddhist nuns
Daughters of emperors