The blind musicians (Biwa hoshi) of Todo-za (the traditional guild for the blind), who were passing down Heikyoku (a narrative music for the Tale of the Heike played with a Heike biwa (a Japanese lute used to play the Tale of the Heike)), perfected the shamisen as an instrument.
平曲（平家琵琶平家物語の語り物音楽）を伝承していた当道座の盲人音楽家（琵琶法師）たちが改良して三味線を完成させた。