This well is said to have been used for the first bath of Hojo Masako at her birth. Masako was born here in 1157 as the eldest daughter of Hojo Tokimasa, a local warrior lord of Izu. She would be united with the exile Minamoto no Yoritomo to become the wife of the first Kamakura shogun, and after his death, as the "Nun Shogun," she remained at the heart of the shogunate, famously rallying the retainers at the time of the Jokyu War. The well's water was once believed to bring safe childbirth, and the site is cherished as a place connected to Masako in Izu, the birthplace of the Hojo clan.