Belldandy and her sisters are based on the Norns, who were the goddesses of fate in Norse mythology. Belldandy (Verthandi) was the goddess of the present. Urd (Urthr, Urdr) controlled the past, and Skuld represented the future. They lived at the base of Yggdrasil, the World Tree. In the original "Aa! Megamisama!" manga, the computer system used by the goddesses is also named Yggdrasil.