In gogyo-setsu (the theory of five elements), spring is in the east, and the god of spring was called Saho-hime, due to the fact that there is Mt. Saho to the east of Heijo-kyo (the ancient capital of Japan in current Nara).
五行説では春は東の方角にあたり、平城京の東に佐保山があるために春の神は佐保姫と呼ぶようになった。