Hiyoribou is a youkai that only shows up when the weather's nice—rain keeps her away. She hangs out in the deep woods around Ibaraki, and spotting her is supposed to be lucky. If you see her, you can count on clear skies that day.
People used to make dolls shaped like Hiyoribou and leave them under the roof as a way to ask for good weather. Over time, this practice evolved into what became Teru Teru Bozu, the hanging doll toy that kids play with today.
Content compiled by AnimeList.moe from publicly available sources.
