There is a tradition that in 1140, he found a knot of bamboo (竹 in kanji, pronounced take) in Satake-ji Temple and was delighted viewing it as a propitious augury, then he called himself Satake.
1140年、佐竹寺において一節の竹を発見し、吉兆と喜び姓を佐竹と称したとする伝承がある。