The full-scale activities of the Akai clan began, when Kuro Tameie was given by his father, Hachiro Ienori, three districts, Hikami-gun, Amata-gun and Ikaruga-gun; while he lived in Akai in 1215.
九郎為家が赤井に住み、1215年に父・八郎家範から氷上、天田郡、何鹿郡の3郡を与えられたことから、赤井氏の本格的な活動が始まる。