When Himegami was a child, her brother Yabiko had a tendency go skirt-chasing after big breasted women, a trait encouraged by their father, Oousu. As their mother was sick (due to being a god who had given birth), she and Yabiko would often go to collect medicinal herbs for her. Himegami's insecurity over her small chest began to develop as she feared her brother would pay no attention to her because of it (given his preference for large ones). However, her mother reassured her that she would grow, saying she was her mother's daughter.
Their family was eventually attacked by her god-hunting uncle, Kousu no Mikoto, causing her parents to sacrifice themselves in order to protect herself and Yabiko, as well as the Maken Habakiri. With her parents slain, Yabiko then sealed her, moments after she inherited her mother's powers, along with Habakiri, away on top of Mount Amanohara. The seal was designed such that it would break when Kousu was dead. As Yabiko left her, he kissed her through the barrier and told her to live, and that he loved her.