Emperor Ichijō
Atsuhira was the second son of Emperor Ichijō. His mother, Fujiwara no Akiko/Shōshi (藤原彰子) (988–1074), was a daughter of Fujiwara no Michinaga. In her later years, Ichijō's "chūgo" consort was known as Jōtō-mon In (上東門院).