In the period of the Northern and Southern Courts (Japan), Yoshinari YOTSUTSUJI stated in "Kakai-sho Commentary" that: "Thorough interpretations of each family are different secrets. Therefore, they are passed down by word of mouth." which means that the meaning of 'Yomei no suke' was kept secret and passed down by word of month without keeping a record.
南北朝時代(日本)の四辻善成になると『河海抄』において「当流両家深奥の説、殊なる秘事となるに依りて口伝にあり」と秘説化しており記録を残さず口伝で伝えるようになっている。