However, both Minoru NOGUCHI and Yasuo MOTOKI guess that he was a grandchild of TAIRA no Sadamichi (Sadamitsu USUI), a roto of MINAMOTO no Yorimitsu, who appeared in 'A story that Yorinobu asked TAIRA no Sadamichi to kill a person' in the tenth section of volume 25 of "Konjaku Monogatari Shu."
しかし、野口実、元木泰雄両名は、『今昔物語集』巻第二十五第十「依頼信言平貞道切人頭語」に出てくる源頼光の郎党、平貞通（道）（碓井貞光）の孫と推定している。