As Dokyo was in Empress Koken's favor, it has widely been believed by scholars of the Heian Period onward that Dokyo fornicated with the Empress or that he had a macropenis, being fondly used as material of folktales as seen in "Nihon Genho Zenaku Ryoiki" (which is a set of three books of Buddhist stories, written in the late 8th and early 9th century, usually referred to as the Nihon Ryoiki) and "Kojidan" (Talks of the Past).
孝謙天皇に寵愛されたことから、平安時代以降の学者によって天皇と姦通していたとする説や巨根説などが唱えられ、『日本現報善悪霊異記』や『古事談』など、説話集の材料にされることも多い。