His imina (real name) was Masahaya, so his name was Masahaya YAGI and, as his family was part of the KUSAKABE Clan, his official name as Ason (second highest of the eight hereditary titles) was KUSAKABE no Masahaya.
諱は応迅（まさはや）であり八木応迅といい、本姓は日下部氏であることから朝臣としての正式な名のりは日下部応迅（くさかべのまさはや）。