Doma hoshi was a member of one of the civilian (illegal) onmyoji groups in Harima Province (present-day Hyogo Prefecture) excelling in magic, and legend has it that he preferred a spell called seman doman (a lattice pattern consisting of 4 vertical and 5 horizontal lines representing 9 letters), or he became known as 'Doman seman' by using ABE no Seimei's seman doman.
播磨国（現在の兵庫県）の民間（ヤミ）陰陽師集団出身で、呪術に長けセーマンドーマン（九字を表す縦4本・横5本の格子模様）という呪符を好んで使ったとか、安倍晴明のセーマンドーマンを使って「ドーマンセーマン」と呼ばれるようになった等の説がある。