These facial expressions were drawn with very fine lines and it is said that when they are copied out on thin papers, "facial expression will be changed if you miss your aim in a fraction of 1mm."
こういった表情は実に細かな描線で描かれており、薄い紙に模写したところで「1ミリの何分の1でも線が狂えば表情は変わってしまう」のだという。